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What is a human being?

When did humans evolve, are neanderthals classified as humans.

human evolution

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Humans are culture-bearing  primates classified in the genus  Homo , especially the species  Homo sapiens . They are anatomically similar and related to the great  apes ( orangutans , chimpanzees , bonobos , and gorillas ) but are distinguished by a more highly developed  brain that allows for the capacity for articulate  speech  and abstract reasoning. Humans display a marked erectness of body carriage that frees the hands for use as manipulative members.

The answer to this question is challenging, since paleontologists have only partial information on what happened when. So far, scientists have been unable to detect the sudden “moment” of evolution for any species, but they are able to infer evolutionary signposts that help to frame our understanding of the emergence of humans. Strong evidence supports the branching of the human lineage from the one that produced great apes (orangutans, chimpanzees, bonobos, and gorillas) in Africa sometime between 6 and 7 million years ago. Evidence of toolmaking dates to about 3.3 million years ago in Kenya . However, the age of the oldest remains of the genus Homo is younger than this technological milestone, dating to some 2.8–2.75 million years ago in Ethiopia . The oldest known remains of Homo sapiens —a collection of skull fragments, a complete jawbone, and stone tools—date to about 315,000 years ago.

Did humans evolve from apes?

No. Humans are one type of several living species of great apes. Humans evolved alongside orangutans, chimpanzees, bonobos, and gorillas. All of these share a common ancestor before about 7 million years ago.

Yes. Neanderthals ( Homo neanderthalensis ) were archaic humans who emerged at least 200,000 years ago and died out perhaps between 35,000 and 24,000 years ago. They manufactured and used tools (including blades, awls, and sharpening instruments), developed a spoken language , and developed a rich culture that involved hearth construction, traditional medicine , and the burial of their dead. Neanderthals also created art ; evidence shows that some painted with naturally occurring pigments . In the end, Neanderthals were likely replaced by modern humans ( H. sapiens ), but not before some members of these species bred with one another where their ranges overlapped.

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human evolution , the process by which human beings developed on Earth from now-extinct primates . Viewed zoologically, we humans are Homo sapiens , a culture -bearing upright-walking species that lives on the ground and very likely first evolved in Africa about 315,000 years ago. We are now the only living members of what many zoologists refer to as the human tribe, Hominini , but there is abundant fossil evidence to indicate that we were preceded for millions of years by other hominins, such as Ardipithecus , Australopithecus , and other species of Homo , and that our species also lived for a time contemporaneously with at least one other member of our genus , H. neanderthalensis (the Neanderthals ). In addition, we and our predecessors have always shared Earth with other apelike primates, from the modern-day gorilla to the long-extinct Dryopithecus . That we and the extinct hominins are somehow related and that we and the apes , both living and extinct , are also somehow related is accepted by anthropologists and biologists everywhere. Yet the exact nature of our evolutionary relationships has been the subject of debate and investigation since the great British naturalist Charles Darwin published his monumental books On the Origin of Species (1859) and The Descent of Man (1871). Darwin never claimed, as some of his Victorian contemporaries insisted he had, that “man was descended from the apes ,” and modern scientists would view such a statement as a useless simplification—just as they would dismiss any popular notions that a certain extinct species is the “ missing link ” between humans and the apes. There is theoretically, however, a common ancestor that existed millions of years ago. This ancestral species does not constitute a “missing link” along a lineage but rather a node for divergence into separate lineages. This ancient primate has not been identified and may never be known with certainty, because fossil relationships are unclear even within the human lineage, which is more recent. In fact, the human “family tree” may be better described as a “family bush,” within which it is impossible to connect a full chronological series of species, leading to Homo sapiens , that experts can agree upon.

(Read T. H. Huxley’s 1875 Britannica essay on evolution & biology.)

The primary resource for detailing the path of human evolution will always be fossil specimens. Certainly, the trove of fossils from Africa and Eurasia indicates that, unlike today, more than one species of our family has lived at the same time for most of human history. The nature of specific fossil specimens and species can be accurately described, as can the location where they were found and the period of time when they lived; but questions of how species lived and why they might have either died out or evolved into other species can only be addressed by formulating scenarios, albeit scientifically informed ones. These scenarios are based on contextual information gleaned from localities where the fossils were collected. In devising such scenarios and filling in the human family bush, researchers must consult a large and diverse array of fossils, and they must also employ refined excavation methods and records, geochemical dating techniques, and data from other specialized fields such as genetics , ecology and paleoecology, and ethology ( animal behaviour )—in short, all the tools of the multidisciplinary science of paleoanthropology .

This article is a discussion of the broad career of the human tribe from its probable beginnings millions of years ago in the Miocene Epoch (23 million to 5.3 million years ago [mya]) to the development of tool -based and symbolically structured modern human culture only tens of thousands of years ago, during the geologically recent Pleistocene Epoch (about 2.6 million to 11,700 years ago). Particular attention is paid to the fossil evidence for this history and to the principal models of evolution that have gained the most credence in the scientific community . See the article evolution for a full explanation of evolutionary theory, including its main proponents both before and after Darwin, its arousal of both resistance and acceptance in society, and the scientific tools used to investigate the theory and prove its validity.

Human Evolution

Six million years of human evolution.

Human evolution is the lengthy process of change by which people originated from apelike ancestors. Scientific evidence shows that the physical and behavioral traits shared by all people originated from apelike ancestors and evolved over a period of approximately six million years.

Paleoanthropology is the scientific study of human evolution which investigates the origin of the universal and defining traits of our species. The field involves an understanding of the similarities and differences between humans and other species in their genes, body form, physiology, and behavior. Paleoanthropologists search for the roots of human physical traits and behavior. They seek to discover how evolution has shaped the potentials, tendencies, and limitations of all people.

What Can Human Fossils Tell Us?

Early human fossils and archeological remains offer the most important clues about this ancient past. These remains include bones, tools and any other evidence (such as footprints, evidence of hearths , or butchery marks on animal bones) left by earlier people. Usually, the remains were buried and preserved naturally. They are then found either on the surface (exposed by rain, rivers, and wind erosion) or by digging in the ground. By studying fossilized bones, scientists learn about the physical appearance of earlier humans and how it changed. Bone size, shape, and markings left by muscles tell us how those predecessors moved around, held tools, and how the size of their brains changed over a long time.

Archeological evidence refers to the things earlier people made and the places where scientists find them. By studying this type of evidence, archeologists can understand how early humans made and used  tools and lived in their environments.

Humans and Our Evolutionary Relatives

Humans are primates . Physical and genetic similarities show that the modern human species, Homo sapiens, has a very close relationship to another group of primate species, the apes. Modern humans and the great apes (large apes) of Africa – chimpanzees (including bonobos, or so-called “pygmy chimpanzees”) and gorillas – share a common ancestor that lived between 8 and 6 million years ago.

Humans first evolved in Africa, and much of human evolution occurred on that continent. The  fossils of early humans who lived between 6 and 2 million years ago come entirely from Africa. Early humans first migrated out of Africa into Asia probably between 2 million and 1.8 million years ago. They entered Europe somewhat later, between 1.5 million and 1 million years. Species of modern humans populated many parts of the world much later. For instance, people first came to Australia probably within the past 60,000 years and to the Americas within the past 15,000 years or so.

Most scientists currently recognize some 15 to 20 different species of early humans. Scientists do not all agree, however, about how these species are related or which ones simply died out. Many early human species – certainly the majority of them – left no living descendants. Scientists also debate over how to identify and classify particular species of early humans, and about what factors influenced the evolution and extinction of each species.

Human Characteristics

One of the earliest defining human traits, bipedalism – the ability to walk on two legs – evolved over 4 million years ago. Other important human characteristics – such as a large and complex brain, the ability to make and use tools, and the capacity for language  – developed more recently. Many advanced traits -- including complex symbolic expression, art , and elaborate cultural diversity – emerged mainly during the past 100,000 years. The beginnings of agriculture and the rise of the first civilizations occurred within the past 12,000 years.

Smithsonian Research Into Human Evolution

The Smithsonian’s Human Origins Program explores the universal human story at its broadest time scale. Smithsonian anthropologists research many aspects of human evolution around the globe, investigating fundamental questions about our evolutionary past, including the roots of human adaptability.

For example, Paleoanthropologist Dr. Rick Potts – who directs the Human Origins Program – co-directs ongoing research projects in southern and western Kenya and southern and northern China that compare evidence of early human behavior and environments from eastern Africa to eastern Asia. Rick’s work helps us understand the environmental changes that occurred during the times that many of the fundamental characteristics that make us human  - such as making tools and large brains – evolved, and that our ancestors were often able to persist through dramatic climate changes. Rick describes his work in the video Survivors of a Changing Environment .

Dr. Briana Pobiner is a Prehistoric Archaeologist whose research centers on the evolution of human diet (with a focus on meat-eating), but has included topics as diverse as cannibalism in the Cook Islands and chimpanzee carnivory. Her research has helped us understand that at the onset of human carnivory over 2.5 million years ago some of the meat our ancestors ate was scavenged from large carnivores, but by 1.5 million years ago they were getting access to some of the prime, juicy parts of large animal carcasses. She uses techniques similar to modern day forensics for her detective work on early human diets.

Paleoanthropologist Dr. Matt Tocheri conducts research into the evolutionary history and functional morphology of the human and great ape family, the Hominidae. His work on the wrist of Homo floresiensis , the so-called “hobbits” of human evolution discovered in Indonesia, received considerable attention worldwide after it was published in 2007 in the journal Science. He now co-directs research at Liang Bua on the island of Flores in Indonesia, the site where Homo floresiensis was first discovered.

Geologist Dr. Kay Behrensmeyer has been a long-time collaborator with Rick Potts’ human evolution research at the site of Olorgesailie in southern Kenya. Kay’s role with the research there is to help understand the environments of the sites at which evidence for early humans – in the form of stone tools as well as fossils of the early humans themselves – have been found, by looking at the sediments of the geological layers in which the artifacts and fossils have been excavated.

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Understanding Evolution

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Human evolution

Evolutionary biologists are interested in understanding how humans fit into the history of life and how the processes of evolution have shaped us. Much scientific effort goes into studying human evolution, and as a result, our understanding of this area is moving forward rapidly, as new evidence emerges and hypotheses are tested, confirmed, discarded, or modified.

The location of our very own twig: Humans on the tree of life

This tree is based on morphological and genetic data. Chimpanzees and humans form a clade with DNA sequences that differ by only 1%. This genetic similarity made it hard to figure out exactly how these two primates are related, but recent genetic studies have strongly suggested that chimpanzees and humans are each other’s closest living relative.

How did humans evolve?

About six million years ago in Africa, the chimpanzee lineage and our own split. What happened to us after that split? The hominid lineage did not march in a straight line to Homo sapiens . Instead, the early hominid lineage gave rise to many other (now extinct) hominids. Examining the fossils, the artifacts, and even the DNA of these relatives has helped us understand how this complex hominid tree evolved, and how modern humans came to exist.

Here are some of the important events in human history, with approximate dates, which reflect the evidence currently available:

• Before 5 mya: In Africa, our ancestral lineage and the chimpanzee lineage split .
• Before 4 mya: The hominid Australopithecus anamensis walked around what is now Kenya on its hind legs.
• 3 mya: Australopithecus afarensis (“ Lucy “) lived in Africa.
• 2.5 mya: Some hominids made tools by chipping stones to form a cutting edge. There were perhaps four or more species of hominid living in Africa.
• 2 mya: The first members of the Homo clade, with their relatively large brains, lived in Africa.
• 1.5 mya: Hand axes were used. Also, hominids had spread out of Africa and into much of Asia and Europe. These hominids included the ancestors of Neanderthals ( Homo neanderthalensis ) in Europe and Homo erectus in Asia.
• 100,000 years ago: Human brains reached more or less the current range of sizes. Early Homo sapiens lived in Africa. At the same time, Homo neanderthalensis and Homo erectus lived in other parts of the Old World.
• 50,000 years ago: Human cultures produced cave paintings and body adornment, and constructed elaborate burials. Also, some groups of modern humans extended their range beyond Africa.
• 25,000 years ago: Other Homo species had gone extinct, leaving only modern humans, Homo sapiens , spread throughout the Old World.
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Learn more about how human evolution factored into the history of evolutionary thought .

Learn more about human evolution in context:

• The genes that lie beneath: The work of Leslea Hlusko , a research profile.
• When it comes to evolution, headlines often get it wrong , a news brief with discussion questions.
• Making sense of ancient hominin DNA , a news brief with discussion questions.

Teach your students about human evolution:

• It's all in your head: An investigation of human ancestry , a classroom activity for grades 9-12.

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September 1, 2020

15 min read

How Scientists Discovered the Staggering Complexity of Human Evolution

Darwin would be delighted by the story his successors have revealed

By Kate Wong

Pascal Blanchet

I n 1859, 14 years after the founding of this magazine, Charles Darwin published the most important scientific book ever written. On the Origin of Species revolutionized society's understanding of the natural world. Challenging Victorian dogma, Darwin argued that species were not immutable, each one specially created by God. Rather life on Earth, in all its dazzling variety, had evolved through descent from a common ancestor with modification by means of natural selection. But for all of Darwin's brilliant insights into the origins of ants and armadillos, bats and barnacles, one species is conspicuously neglected in the great book: his own. Of Homo sapiens , Darwin made only a passing mention on the third-to-last page of the tome, noting coyly that "light will be thrown on the origin of man and his history." That's it. That is all he wrote about the dawning of the single most consequential species on the planet.

It was not because Darwin thought humans were somehow exempt from evolution. Twelve years later he published a book devoted to that very subject, The Descent of Man . In it, he explained that discussing humans in his earlier treatise would have served only to further prejudice readers against his radical idea. Yet even in this later work, he had little to say about human origins per se, instead focusing on making the case from comparative anatomy, embryology and behavior that, like all species, humans had evolved. The problem was that there was hardly any fossil record of humans to provide evidence of earlier stages of human existence. Back then, "the only thing you knew was what you could reason," says paleoanthropologist Bernard Wood of the George Washington University.

To his credit, Darwin made astute observations about our kind and predictions about our ancient past based on the information that was available to him. He argued that all living humans belong to one species and that its "races" all descended from a single ancestral stock. And pointing to the anatomical similarities between humans and African apes, he concluded that chimpanzees and gorillas were the closest living relatives of humans. Given that relationship, he figured, early human ancestors probably lived in Africa.

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Since then, Wood says, "the evidence has come in." In the past century and a half, science has confirmed Darwin's prediction and pieced together a detailed account of our origins. Paleoanthropologists have recovered fossil hominins (the group that comprises H. sapiens and its extinct relatives) spanning the past seven million years. This extraordinary record shows that hominins indeed got their start in Africa, where they evolved from quadrupedal apes into the upright-walking, nimble-fingered, large-brained creatures we are today.

And the archaeological record of hominin creations, which encompasses roughly half that time, charts their cultural evolution—from early experiments with simple stone tools to the invention of symbols, songs and stories—and maps our ancestors' spread across the globe. The fossils and artifacts demonstrate that for most of the period over which our lineage has been evolving, multiple hominin species walked the earth. Studies of modern and ancient DNA have generated startling insights into what happened when they encountered one another.

Neandertals were the first extinct hominin species to be recognized in the fossil record and the first to yield ancient DNA. Credit: Javier Trueba/Science Source

The human saga, we now understand, is far more intricate than scholars of yore envisioned. The tidy tropes of our prehistory have collapsed under the weight of evidence: there is no single missing link that bridges apes and humankind, no drumbeat march of progress toward a predestined goal. Our story is complicated, messy and random. Yet it still can be accommodated under Darwin's theory of evolution and in fact further validates that framework.

This is not to say scientists have it all figured out. Many questions remain. But whereas the origin of humans was once an uncomfortable speculation in Darwin's big idea, it is now among the best-documented examples of evolution's transformative power.

We humans are strange creatures. We walk upright on two legs and possess supersized brains, we invent tools to meet our every need and express ourselves using symbols, and we have conquered every corner of the planet. For centuries scientists have sought to explain how we came to be, our place in the natural world.

This quest was often distorted by racist ideologies. Consider the era leading up to the birth of Darwin's bombshell theory. In the 1830s, while a young Darwin was making his momentous voyage onboard the Beagle , a movement was underway to promote the idea that the various modern human groups around the globe—races—had separate origins. To build the case for polygenism, as the theory is known, scientists such as Samuel Morton in Philadelphia collected skulls from people across the world and measured their sizes and shapes, falsely believing those attributes to be proxies for intelligence. When they ranked the specimens from superior to inferior, Europeans would conveniently come out on top and Africans on the bottom. "There was a desire to provide scientific justification for political and power structures," says anthropological geneticist Jennifer Raff of the University of Kansas. "It was science in the service of slavery and colonialism."

Although Darwin's work came down firmly on the side of monogenism—the idea that all humans share a common ancestor—it was nonetheless co-opted to support notions about racial superiority. Social Darwinism, for one, misapplied Darwin's ideas about the struggle for existence in natural selection to human society, providing a pseudoscientific rationalization for social injustice and oppression. Darwin himself did not subscribe to such views. In fact, his opposition to slavery might have been a driving force in his research agenda, according to his biographers Adrian Desmond and James Moore.

By the time Darwin published The Descent of Man , in 1871, the idea that humans had evolved from a common ancestor with apes was already gaining traction in the scientific community thanks to books published in the 1860s by English biologist Thomas Henry Huxley and Scottish geologist Charles Lyell. Still, the fossil evidence to support this claim was scant. The only hominin fossils known to science were a handful of remains a few tens of thousands of years old that had been recovered from sites in Europe. Some were H. sapiens; others would eventually be recognized as a separate but very closely related species, Homo neanderthalensis . The implication was that fossils of more apelike human ancestors were out there somewhere in the world, awaiting discovery. But the suggestion by Darwin, like Huxley before him, that those ancestors would be found in Africa met with resistance from scholars who saw Asia as a more civilized birthplace for humankind and emphasized similarities between humans and Asia's gibbons.

Perhaps it should come as no surprise, then, that when the first hominin fossil significantly older and more primitive than those from Europe turned up, it came not from Africa but from Asia. In 1891 Dutch anatomist Eugène Dubois discovered remains on the Indonesian island of Java that he thought belonged to the long-sought missing link between apes and humans. The find, which he named Pithecanthropus erectus , spurred further efforts to root humankind in Asia. (We now know that Dubois's fossil was between 700,000 and one million years old and belonged to a hominin that was much more humanlike than apelike, Homo erectus .)

Two decades later the search turned to Europe. In 1912 amateur archaeologist Charles Dawson reported that he had found a skull with a humanlike cranium and an apelike jaw in an ancient gravel pit near the site of Piltdown in East Sussex, England. Piltdown Man, as the specimen was nicknamed, was a leading contender for the missing link until it was exposed in 1953 as a fraudulent pairing of a modern human skull with an orangutan's lower jaw.

Piltdown so seduced scholars with the prospect of making Europe the seat of human origins that they all but ignored an actual ancient hominin that turned up in Africa, one even older and more apelike than the one Dubois discovered. In 1925, 43 years after Darwin's death, anatomist Raymond Dart published a paper describing a fossil from Taung, South Africa, with an apelike braincase and humanlike teeth. Dart named that fossil—a youngster's skull now known to be around 2.8 million years old— Australopithecus africanus , "the southern ape from Africa." But it would take nearly 20 years for the scientific establishment to accept Dart's argument that the so-called Taung Child was of immense significance: the fossil linked humans to African apes.

Evidence of humanity's African origins has accumulated ever since. Every hominin trace older than 2.1 million years—and there are now quite a few of them—has come from that continent.

Even as fossil discoveries proved Darwin right about the birthplace of humanity, the pattern of our emergence remained elusive. Darwin himself depicted evolution as a branching process in which ancestral species divide into two or more descendant species. But a long-standing tradition of organizing nature hierarchically—one that dates back to Plato and Aristotle's Great Chain of Being—held sway, giving rise to the notion that our evolution unfolded in linear fashion from simple to complex, primitive to modern. Popular imagery reflected and reinforced this idea, from a caricature in Punch's Almanack for 1882 showing a progression from earthworm to Darwin, to the iconic monkey-to-man illustration that appeared in the 1965 Time-Life book Early Man and became known as the March of Progress.

From the rich assortment of fossils and artifacts recovered from around the world in the past century, however, paleoanthropologists can now reconstruct something of the timing and pattern of human evolution. The finds clearly show that this single-file scheme is no longer tenable. Evolution does not march steadily toward predetermined goals. And many hominin specimens belong not in our direct line of ancestry but on side branches of humankind—evolutionary experiments that ended in extinction.

From the outset, our defining traits evolved not in lockstep but piecemeal. Take our mode of locomotion, for example. H. sapiens is what anthropologists call an obligate biped—our bodies are built for walking on two legs on the ground. We can climb trees if we need to, but we have lost the physical adaptations that other primates have to arboreal life. Fragmentary fossils of the oldest known hominins— Sahelanthropus tchadensis from Chad, Orrorin tugenensis from Kenya and Ardipithecus kadabba from Ethiopia—show that our earliest ancestors emerged by around seven million to 5.5 million years ago. Although they are apelike in many respects, all of them exhibit characteristics associated with walking on two legs instead of four. In Sahelanthropus , for example, the hole in the base of the skull through which the spinal cord passes has a forward position suggestive of an upright posture. A bipedal gait may thus have been one of the very first traits that distinguished hominins from ancestral apes.

Yet our forebears appear to have retained traits needed for arboreal locomotion for millions of years after they first evolved the ability to walk on two legs. Australopithecus afarensis , which lived in eastern Africa from 3.85 million to 2.95 million years ago and is famously represented by the skeleton known as Lucy, discovered in 1974, was a capable biped. But it had long, strong arms and curved fingers—features associated with tree climbing. It would be another million years before modern limb proportions evolved and committed hominins to life on the ground, starting with early H. erectus in Africa (sometimes called Homo ergaster ).

The brain evolved on quite a different schedule. Over the course of human evolution, brain size has more than tripled. A comparison of the braincase of A. afarensis with that of the much older Sahelanthropus , however, shows that hardly any of that growth occurred in the first few million years of human evolution. In fact, most of the expansion took place in the past two million years, perhaps enabled by a feedback loop in which advances in technology—stone tools and the like—gave hominins access to more nutritious foods such as meat, which could fuel a larger and thus more energetically demanding brain, which in turn could dream up even better technology, and so on. Shifts in the shape and structure of the brain accompanied these gains, with more real estate allocated to regions involved in language and long-range planning, among other advanced cognitive functions.

This mosaic pattern of hominin evolution in which different body parts evolved at different rates produced some surprising creatures. For instance, Australopithecus sediba from South Africa, dated to 1.98 million years ago, had a humanlike hand attached to an apelike arm, a big birth canal but a small brain, and an advanced ankle bone connected to a primitive heel bone.

Sometimes evolution even doubled back on itself. When one examines a hominin fossil, it can be difficult to discern whether the species retained a primitive trait such as small brain size from an earlier ancestor or whether it lost the characteristic and then re-evolved it. But the strange case of Homo floresiensis may well be an example of the latter. This member of the human family lived on the island of Flores in Indonesia as recently as 50,000 years ago yet looked in many ways like some of the founding members of our genus who lived more than two million years earlier. Not only did H. floresiensis have a small body, but it also possessed a remarkably tiny brain for Homo , about the size of a chimp's. Scientists' best guess is that this species descended from a brawnier, brainer Homo species that got marooned on Flores and evolved its diminutive size as an adaptation to the limited food resources available on its island home. In so doing, H. floresiensis seems to have reversed what researchers once considered a defining trend of Homo 's evolution: the inexorable expansion of the brain. Yet despite its small brain, H. floresiensis still managed to make stone tools, hunt animals for food and cook over fires.

Adding to the complexity of our story, it is now clear that for most of the time over which humans have been evolving, multiple hominin species walked the earth. Between 3.6 million and 3.3 million years ago, for example, at least four varieties of hominins lived in Africa. Paleoanthropologist Yohannes Haile-Selassie of Arizona State University's Institute of Human Origins and his colleagues have recovered remains of two of them, A. afarensis and Australopithecus deyiremeda , as well as a possible third creature known only from a distinctive fossil foot, in an area called Woranso-Mille in Ethiopia's Afar region. How they managed to share the landscape is a subject of current investigation. "Competing species could co-exist if there were plenty of resources or if they were exploiting different parts of the ecosystem," Haile-Selassie says.

Later, between roughly 2.7 million and 1.2 million years ago, representatives of our genus, Homo —large-brained tool users with dainty jaws and teeth—shared the grasslands of southern and eastern Africa with a radically different branch of humanity. Members of the genus Paranthropus , these hominins had massive teeth and jaws, flaring cheekbones and crests atop their heads that anchored powerful chewing muscles. Here the co-existence is somewhat better understood: whereas Homo seems to have evolved to exploit a wide variety of plants and animals for food, Paranthropus specialized in processing tough, fibrous plant foods.

H. sapiens overlapped with other kinds of humans, too. When our species was evolving in Africa 300,000 years ago, several other kinds of hominins also roamed the planet. Some, such as the stocky Neandertals in Eurasia, were very close relatives. Others, including Homo naledi in South Africa and H. erectus in Indonesia, belonged to lineages that diverged from ours in the deep past. Even as recently as 50,000 years ago, hominin diversity was the rule, with the Neandertals, the mysterious Denisovans from Asia, tiny H. floresiensis and another small hominin— Homo luzonensis from the Philippines—all at large.

Such discoveries make for a much more interesting picture of human evolution than the linear account that has dominated our view of life. But they raise a nagging question: How did H. sapiens end up being the sole surviving twig on what was once a luxuriant evolutionary bush?

Here are the facts of the case. We know from fossils found at the site of Jebel Irhoud in Morocco that our species originated in Africa by at least 315,000 years ago. By around 200,000 years ago it began making forays out of Africa, and by 40,000 years ago it had established itself throughout Eurasia. Some of the places H. sapiens colonized were occupied by other hominin species. Eventually the other folks all disappeared. By around 30,000 to 15,000 years ago, with the end of the Neandertals in Europe and the Denisovans in Asia, H. sapiens was alone in the world.

Researchers have often attributed the success of our species to superior cognition. Although the Neandertals actually had slightly larger brains than ours, the archaeological record seemed to indicate that only H. sapiens crafted specialized tools and used symbols, suggesting a capacity for language. Perhaps, the thinking went, H. sapiens won out by virtue of sharper foresight, better technology, more flexible foraging strategies and bigger social networks for support against hard times. Alternatively, some investigators have proposed, maybe H. sapiens waged war on its rivals, exterminating them directly.

But recent discoveries have challenged these scenarios. Neandertal technology, archaeologists have learned, was far more varied and sophisticated than previously thought. Neandertals, too, made jewelry and art, crafting pendants from shells and animal teeth and painting abstract symbols on cave walls. Moreover, they might not have been our only enlightened kin: a 500,000-year-old engraved shell from Java suggests that H. erectus also possessed symbolic thought. If archaic hominins had many of the same mental faculties as H. sapiens , why did the latter prevail?

The conditions under which H. sapiens got its start might have played a role. Fossil and archaeological data suggest that our species mostly stayed in Africa for the first couple of hundred thousand years of its existence. There, some experts argue, it evolved as a population of interconnected subgroups spread across the continent that split up and reunited again and again over millennia, allowing for periods of evolution in isolation followed by opportunities for interbreeding and cultural exchange. This evolutionary upbringing might have honed H. sapiens into an especially adaptable hominin. But that is not the whole story, as we now know from genetics.

Analyses of DNA have revolutionized the study of human evolution. Comparing the human genome with the genomes of the living great apes has shown conclusively that we are most closely related to chimpanzees and bonobos, sharing nearly 99 percent of their DNA. And large-scale studies of DNA from modern-day human populations across the globe have illuminated the origins of modern human variation, overturning the centuries-old notion that races are biologically discrete groups with separate origins. "There have never been pure populations or races," Raff says. Modern human variation is continuous, and most variation exists within populations rather than between them—the product of our demographic history as a species that originated in Africa with populations that mixed continuously as they migrated around the world.

More recently, studies of ancient DNA have cast new light on the world of early H. sapiens as it was when other hominin species were still running around. In the late 1990s geneticists began recovering small amounts of DNA from Neandertal and early H. sapiens fossils. Eventually they succeeded in getting entire genomes not only from Neandertals and early H. sapiens but also from Denisovans, who are known from just a few fragmentary fossils from Siberia and Tibet. By comparing these ancient genomes with modern ones, researchers have found evidence that our own species interbred with these other species. People today carry DNA from Neandertals and Denisovans as a result of these long-ago encounters. Other studies have found evidence of interbreeding between H. sapiens and unknown extinct hominins from Africa and Asia for whom we have no fossils but whose distinctive DNA persists.

Mating with other human species might have aided H. sapiens' success. Studies of organisms ranging from finches to oak trees have shown that hybridization with local species can help colonizing species flourish in novel environments by giving them useful genes. Although scientists have yet to figure out the functions of most of the genes people today carry from extinct hominins, they have pinpointed a few, and the results are intriguing. For instance, Neandertals gave H. sapiens immunity genes that might have helped our species fend off novel pathogens it encountered in Eurasia, and Denisovans contributed a gene that helped people adapt to high altitudes. H. sapiens may be the last hominin standing, but it got a leg up from its extinct cousins.

Scientists have many more pieces of the human-origins puzzle than they once did, but the puzzle is now vastly bigger than it was previously understood to be. Many gaps remain, and some may never close. Take the question of why we evolved such massive brains. At around 1,400 grams, the modern human brain is considerably larger than expected for a primate of our body size. "The singularity is why it's interesting—and why it's impossible to answer scientifically," Wood observes. Some experts have suggested that hominin brains ballooned as they adapted to climate fluctuations between wet and dry conditions, among other explanations. But the problem with trying to answer "why" questions about the evolution of our unique traits, Wood says, is that there is no way to evaluate the proposed explanations empirically: "There isn't a counterfactual. We can't go back to three million years ago and not change the climate."

Other mysteries may yield to further investigation, however. For example, we do not yet know what the last common ancestor of humans and the Pan genus that includes chimps and bonobos looked like. Genomic and fossil data suggest that the two lineages diverged between eight million and 10 million years ago—up to three million years before the oldest known hominin lived—which means that paleoanthropologists may be missing a substantial chunk of our prehistory. And they have hardly any fossils at all of Pan , which has been evolving along its own path just as long as we have. Insights may come from a project currently underway in central Mozambique, where Susana Carvalho and Ren Bobe of the University of Oxford and their colleagues are hunting for fossil primates, including hominins, in sediments older than the ones that yielded Sahelanthropus, Orrorin and Ardipithecus .

Later stages of the human story are riddled with unknowns, too. If H. sapiens was interbreeding with the other hominin species it encountered, as we now know it was, were these groups also exchanging culture? Might H. sapiens have introduced Neandertals to novel hunting technology and artistic traditions—or vice versa? New techniques for retrieving ancient DNA and proteins from otherwise unidentifiable fossils and even cave sediments are helping researchers determine which hominin species were active and when at key archaeological sites.

One wonders where the next discovery will take us in the quest to understand who we are and where we come from. We may have found our place in nature, located our twig on the shrub, but we are still searching for ourselves. We're only human, after all.

Credit: Moritz Stefaner and Christian Lässer For more context, see “ Visualizing 175 Years of Words in Scientific American ”

Kate Wong is an award-winning science writer and senior editor at Scientific American focused on evolution, ecology, anthropology, archaeology, paleontology and animal behavior. She is fascinated by human origins, which she has covered for more than 25 years. Recently she has become obsessed with birds. Her reporting has taken her to caves in France and Croatia that Neandertals once called home, to the shores of Kenya's Lake Turkana in search of the oldest stone tools in the world, to Madagascar on an expedition to unearth ancient mammals and dinosaurs, to the icy waters of Antarctica, where humpback whales feast on krill, and on a "Big Day" race around the state of Connecticut to find as many bird species as possible in 24 hours. Kate is co-author, with Donald Johanson, of Lucy's Legacy: The Quest for Human Origins . She holds a bachelor of science degree in biological anthropology and zoology from the University of Michigan. Follow Wong on X (formerly Twitter) @katewong

At the Smithsonian | December 27, 2022

Fourteen Discoveries Made About Human Evolution in 2022

Smithsonian paleoanthropologists reveal the year’s most riveting findings about our close relatives and ancestors

A team led by Laurits Skov and Benjamin Peter from the Max Planck Institute for Evolutionary Anthropology sequenced nuclear, mitochondrial and Y-chromosome DNA of 13 Neanderthal individuals. From these sequences, they determined that two of the Neanderthals represent a father-daughter pair and that another two are cousins.

Ryan McRae and Briana Pobiner

With many projects around the world proceeding despite the Covid-19 pandemic, researchers across a variety of fields made multiple exciting breakthroughs on human origins, gaining more insight into topics ranging from food and drink to interspecies cooperation.

Telling us more about our food, our health, our close relatives and ancestors, and even our animal friends, these 14 new discoveries scientists made this year shed more light on what it means to be human.

Meat, fire and beer: origins of modern food staples

For decades, one of the hallmarks of human evolution has been the presumed shift from a predominantly plant-based diet to one that included significant amounts of meat and animal tissue. Scientists surmised that since meat is generally more nutrient-dense, more meat-eating could have allowed our ancestors, beginning with the emergence of Homo erectus around 2 million years ago, to evolve the large and energetically demanding brains that we associate with our own species.

But the question remained: Did meat consumption actually increase after this time, inferred by stone tool butchery marks on fossilized bones, or is there just more fossil material overall from that period—making it more likely to find these butchery marks?

In January, W. Andrew Barr from George Washington University and colleagues examined all the fossil evidence for butchery in eastern Africa from 1.2 million years ago and older. They concluded that the evidence for increased carnivory in our ancestors is merely an effect of increased sampling of the archaeological record at certain time intervals starting around two million years ago, meaning that there is no strong relationship between eating more meat and the evolution of larger brains in our ancestors.

Well, if it wasn’t meat eating that enabled big brains to evolve, maybe it was cooking?

Cooking makes food easier to digest, allowing for the extraction of more nutrients from food while expending less energy. The earliest evidence for human control of fire dates back to at least one million years ago, but the earliest evidence for using fire to cook food is much more recent.

In November, a team led by Irit Zohar from Tel Aviv University made breakthrough discoveries from the Israeli site Gesher Benot Ya’aqov that pushed this date back to around 600,000 years ago with new evidence for hominins cooking fish. Teeth of a species of carp were subjected to temperatures required to cook fish, but not as hot as temperatures directly inside a fire would be. This indicates the fish were placed above or next to the fire for cooking rather than being discarded in the fire or burned accidentally.

Of course, what good is barbecue without a tasty beverage to wash it down? In December 2021, a team led by Jiajing Wang from Dartmouth University uncovered the oldest known beer production in the world in Egypt. Made of fermented grains, the production of beer is closely linked to the emergence and spread of agricultural societies.

Dating to 5,800 years ago, hundreds of years before Egypt’s first pharaoh, this beer was thick like a porridge rather than watery and probably used for both daily consumption and ritual purposes. Yum?

Animal friends and animal food: origins of domestication and cooperation

Whether for work, companionship or food, domesticated animals make modern human existence possible. But do human impacts on animal communities in a broader sense date back far earlier than evidence for domestication?

In July, a team led by Danielle Fraser from the Canadian Museum of Nature quantified species evenness in North America over the past 20,000 years and found that there were two periods when the diversity of animal communities notably decreased. The first, around 10,000 years ago, was associated with the North American megafauna extinction. The other occurred around 2,000 years ago during a period in which agriculture spread rapidly and population sizes boomed.

This study demonstrates that humans can affect, and have affected, animal communities in indirect ways in addition to hunting and domestication.

When it comes to domesticated animals, perhaps none captures the imagination and our emotions like humankind’s best friend—the dog.

Dogs are also currently the earliest known domesticated animal on earth. A June study led by Anders Bergström and Pontus Skoglund of the Francis Crick Institute looked at genomes of ancient wolves, from whom our species domesticated the modern dog, to try to determine where and when the connection between humans and dogs began.

They found that ancient wolf populations in North America, Europe and Siberia were interconnected with each other in the past rather than being separate populations as they are today, and that all dogs included in the study are most closely related to wolves from eastern Eurasia rather than from western Eurasia.

However, ancient wolves in southwest Eurasia made significant contributions to the genome of dogs originating from the Near East and Africa—either indicating a separate domestication process or, more likely, interbreeding with that additional wolf population early in the process (just as early members of our own species interbred with Neanderthals when we first left Africa).

While this study points strongly to eastern Eurasia as the geographic source of modern dogs, none of the ancient wolf populations studied were the direct ancestor of modern dogs, meaning that the true dog ancestor (or ancestors) is yet to be found.

In addition to companionship, humans also domesticated animals for food and to assist with work. A study in June led by Joris Peters from Ludwig Maximilian University Munich and Greger Larson from the University of Oxford traced the origin of chicken domestication to around 1650 B.C.E. in Thailand, corresponding to the spread of grains (specifically rice and millet). Chickens then appear to follow the grains as they spread around the world as a food source.

Clearly, modern humans owe a lot to our animal friends, and new finds continue to shed light on where, when and how these interspecies interactions first emerged.

New fossils shed light on old ancestors: discoveries from our earliest and most recent evolutionary history

As in previous years, 2022 revealed more fossil finds tied to our human lineage’s earliest history.

One of the first possible hominins, Sahelanthropus tchadensis , dates to around six to seven million years ago and was found in Chad in Central Africa. This species was previously known only by cranial remains and a partial femur, but in August a team led by Guillaume Daver and Franck Guy from the University of Poitiers reinterpreted the femur (upper leg bone) and described two ulnae (forearm bones). These ulnae share many affinities with our ape relatives and suggest that while Sahelanthropus may have been bipedal on the ground, its arms were still well adapted to climbing and clambering in trees.

On the more recent side of prehistory: New fossils of the enigmatic Denisovans , known mostly from their DNA, are starting to tell us more about where they lived and what they looked like. Following up on a Denisovan mandible found in Tibet in 2019, a Denisovan molar was recently discovered in Laos. Dating to between 130,000 to 160,000 years old, this is the first Denisovan fossil found in a geographic area where scientists now know their DNA wound up. Many populations of modern Southeast Asian, Papuan and Filipino people have some Denisovan DNA in them— up to five percent in one Indigenous Filipino group . We’re looking forward to more new finds of Denisovan fossils to tell us more about who they were and what they looked like, as well as when and how they interacted with our own species.

Speaking of species interactions, new finds in February from a cave in southeast France are complicating the story of human-Neanderthal co-occupation of Europe. A team led by Ludovic Slimak from the University of Toulouse unearthed evidence of hominin occupation at a site called Grotte Mandrin in France: First Neanderthals were there, then modern humans, then Neanderthals again before modern humans became the only hominin in Europe.

From both lithic and fossil evidence, this modern human occupation dates to older than 50,000 years ago, almost 10,000 years older than the previous record for modern humans in this region. This evidence tells us that not only did Neanderthals and modern humans live in the same area for a long span of time (potentially implying that our presence in Europe did not drive Neanderthals to extinction), but also that these two species occupied the same site alternately. This extended timespan of interaction could have implications for genetics as well, potentially adding another data point to the where and when of modern human-Neanderthal interbreeding .

Friends and family ties in modern apes and Neanderthals

While most studies of apes focus on groups of only one species at a time, some apes, like chimpanzees and gorillas, do overlap in multiple locations—providing an opportunity to observe the interactions between them. Often when two closely related species overlap in range, their actions are predominantly antagonistic or aggressive toward the other group.

But in the Nouabalé-Ndoki National Park in the Congo Republic, chimpanzees and gorillas have been observed being downright friendly with each other. From the two species foraging in the same tree, to their young playing with each other, to individuals forming lasting friendships, chimps and gorillas have generally gotten along over the 20-year period of study led by Crickette Sanz of Washington University in St. Louis, which was announced in October. This interspecies cooperation may offer a large advantage in deterring predators like leopards and in helping each other find valuable food sources.

While it is relatively straightforward to observe group dynamics in living apes, figuring out how now-extinct early human groups lived and interacted is much trickier, as population-level studies require multiple fossils from the same site at the same time period.

Between two cave sites in southern Siberia (the Chagyrskaya and Okladnikov caves), in October a team led by Laurits Skov and Benjamin Peter from the Max Planck Institute for Evolutionary Anthropology sequenced nuclear, mitochondrial and Y-chromosome DNA of 13 Neanderthal individuals. From these sequences, they determined that two of the Neanderthals represent a father-daughter pair and that another two are cousins.

Additionally, evidence points to one-third of the Neanderthals being part of the same tightly knit community living around 54,000 years ago. Such small-scale resolution is almost unheard of in paleoanthropology. Analysis of the Y-chromosome (passed on through males) and mitochondrial (passed on through females) DNA reveals that the individuals had significantly less diverse Y-chromosome DNA, indicating that Neanderthal females were the ones to relocate to different groups, diversifying the mitochondrial DNA gene pool—in much the same pattern as has been observed in living chimpanzees.

These findings give us new insights into Neanderthal social structure, and potentially even to how interbreeding with our own species may have occurred.

How disease shapes us, and how we evolved to treat it

Modern medicine is thought to have arisen at least by the time of agriculture and large-scale population centers, possibly as a result of their development. More people means more disease, and humans would have looked for new ways to treat diseases. But something as medically complex as limb amputations were only known to occur as far back as 7,000 years ago and were not commonly known until a few hundred years ago, long after the rise of agricultural societies.

However, a new finding out of Borneo in Indonesia pushes this date back to as much as 31,000 years ago. A team led by Tim Maloney from Griffith University in Australia suggests that this individual appears to have had their leg surgically amputated just above the ankle, and then proceeded to live for another six to nine years based on bone remodeling around the amputation site. This evidence implies that modern humans had complex medical knowledge, such as how to locate and sever blood vessels, nerves, muscle tissue and bone, both safely and effectively, long before the advent of agriculture.

Yet, medicinal knowledge is not relegated to our own species. While animals like elephants, bears and other apes have been known to ingest material for medicinal purposes, it was not until this year that a team led by Simone Pika from the University of Osnabrück observed apes using topical ointments for healing . After catching insects, the wild chimpanzees from the Rekambo community in Gabon then squished them between their lips, rubbed the insect in the wound and removed the insect afterward.

The truly groundbreaking part of the study, announced in February, is that the chimpanzees treated not only their own wounds but also other chimps’ wounds. This sort of caring behavior was assumed to be reserved for our own species, but it seems like caring for others in one’s community could have deeper roots in our evolutionary history.

Another new study out in July led by Pascal Gagneux and Ajit Varki of the University of California San Diego looked at the intersection of medicine and genetics to explore why modern humans have developed such a long post-reproductive lifespan.

The “ grandmother hypothesis ” posits that modern humans live well past sexual maturity in order to care for family members, specifically grandchildren. But when did this long lifespan evolve— and how? A specific gene that produces immune receptors (like specialized parts of immune system cells) called CD33 allows modern humans to prevent some side effects of aging, specifically protecting the brain from inflammation and dementia. The gene for these CD33 receptors is not present in Neanderthals or Denisovans, meaning that it could be one advantage our species had over them, but it also means we had to have acquired it on our own rather than inheriting the gene from a common ancestor. One hypothesis this study explored comes from reproductive health: the idea that we evolved these receptors to fight gonorrhea bacteria. The bacterium coats itself in sugars to mimic the human body, and our version of the CD33 receptors can effectively fight it—sparing our reproductive health. This potentially indicates that this adaptation to reproductive health could have been co-opted by the human body to allow for longer lifespans. In other words, we evolved the CD33 receptors to fight gonorrhea, and as a result our bodies could fight against dementia and allow us to become grandparents.

Most notable: a new 2022 Nobel Laureate

While important strides have been made in genetics and human evolution in the past year, the most notable achievement must go to a new Nobel laureate Svante Pääbo . Born in Sweden in 1955, Pääbo has long been a leader in the field of ancient DNA, especially when it comes to humans and our closest relatives.

In 2010, Pääbo’s team deciphered the Neanderthal genome, unlocking a whole new realm of anthropological insight. Pääbo has also been at the forefront of new discoveries in anthropology, including identifying the Denisovans and understanding the genetic relationships among Denisovans, Neanderthals and our own species, as well as identifying the first early human Neanderthal-Denisovan hybrid . For these reasons and more, Pääbo was awarded the 2022 Nobel Prize in Physiology or Medicine, a fantastic way to round out 2022. Congratulations!

A version of this article was originally published on the PLOS SciComm blog.

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Ryan McRae | READ MORE

Dr. Ryan McRae is a paleoanthropologist studying the hominin fossil record on a macroscopic scale. He currently works for the National Museum of Natural History’s Human Origins Program as a contractor focusing on research, education, and outreach, and is an adjunct assistant professor of anatomy at the George Washington University School of Medicine and Health Sciences.

Briana Pobiner | READ MORE

Briana Pobiner is a paleoanthropologist with the National Museum of Natural History’s Human Origins Program . She lead's the program's education and outreach efforts. 

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How scientists perceive the evolutionary origin of human traits: Results of a survey study

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Data are available from the Dryad Digital Repository: https://doi.org/10.5061/dryad.s9r98

Various hypotheses have been proposed for why the traits distinguishing humans from other primates originally evolved, and any given trait may have been explained both as an adaptation to different environments and as a result of demands from social organization or sexual selection. To find out how popular the different explanations are among scientists, we carried out an online survey among authors of recent scientific papers in journals covering relevant fields of science (paleoanthropology, paleontology, ecology, evolution, human biology). Some of the hypotheses were clearly more popular among the 1,266 respondents than others, but none was universally accepted or rejected. Even the most popular of the hypotheses were assessed “very likely” by <50% of the respondents, but many traits had 1–3 hypotheses that were found at least moderately likely by >70% of the respondents. An ordination of the hypotheses identified two strong gradients. Along one gradient, the hypotheses were sorted by their popularity, measured by the average credibility score given by the respondents. The second gradient separated all hypotheses postulating adaptation to swimming or diving into their own group. The average credibility scores given for different subgroups of the hypotheses were not related to respondent's age or number of publications authored. However, (paleo)anthropologists were more critical of all hypotheses, and much more critical of the water‐related ones, than were respondents representing other fields of expertise. Although most respondents did not find the water‐related hypotheses likely, only a small minority found them unscientific. The most popular hypotheses were based on inherent drivers; that is, they assumed the evolution of a trait to have been triggered by the prior emergence of another human‐specific behavioral or morphological trait, but opinions differed as to which of the traits came first.

1. INTRODUCTION

Human evolution is a topic that interests not just researchers specialized in paleoanthropology, but also other scientists and the general public. A number of conflicting hypotheses have been put forward to explain why humans have become strikingly different from other primates. Most scientists in relevant fields (such as paleoanthropology, paleontology, ecology, evolution and human biology) have never published their views on the drivers of human evolution in general, nor on which of the proposed hypotheses on the origin of specific human traits they find most substantiated. No recent summary of the mainstream view among paleoanthropologists has been published either, so there is uncertainty as to whether scientists agree on the driving forces behind human evolution or not. The idea of carrying out a survey to find out emerged when one of us was teaching a university course on human evolution, happened to check what Wikipedia had to say on the subject, and noticed that some Talk pages (especially the one behind the article “Aquatic ape hypothesis”) contained definite but unreferenced claims about what the opinions of “all scientists” or “all paleoanthropologists” are.

Humans differ from all the other 400 primate species in many respects, some of the most striking ones being that they walk fully upright on their hind legs, have unusually big brains, and have an effectively naked rather than fur‐covered skin (Figure  1 ). Other features that among primates are uniquely human include descended larynx, articulated speech and the capacity to accumulate fat in a thick subcutaneous layer.

Male and female human figures from the plaque of the Pioneer 10 and 11 spacecrafts. The pictorial message was intended to describe the origin of the probe for potential extraterrestrial life. It shows several typically human traits, such as bipedalism, nakedness, arched nose, large head, and opposable thumbs. Source: NASA ; vectors by Mysid (Public domain), via Wikimedia Commons

A number of conflicting hypotheses have been proposed to explain why these and other traits originally evolved in the lineage leading to humans but in none of the lineages leading to other extant primates. One line of argumentation is based on the widely accepted idea that animal species adapt to their environment by natural selection: Traits that give the animal a higher probability of survival and reproduction become more common over time and traits related to lower survival and reproduction rates become less common. Adaptive traits are often morphological (like long legs that increase running speed and facilitate escaping from predators, or thick fur that protects from heat loss in cold weather), but they can also be behavioral (like building a nest or being nocturnal). The corollary of viewing traits of a species as adaptations to its environment is that traits are expected to change if the environment changes, because then also the adaptive pressures change. In particular, if sister species have very different traits in spite of close genetic relatedness, the adaptationist scenario suggests that the lineages experienced different environments during their evolutionary past.

It has indeed been proposed that the ancestors of humans came to live in a different kind of environment than the ancestors of chimpanzees and gorillas, and adapted by evolving a suite of novel traits. One of the early proposals along these lines, suggested already by Lamarck and Darwin, was that human ancestors descended from the trees and moved to the open savanna (Bender, Tobias, & Bender, 2012 ; Dart, 1925 ; Domínguez‐Rodrigo, 2014 ; Leakey & Lewin, 1977 ). Because terrestrial life in the dry savanna is very different from arboreal life in wet forests, this change in habitat would have shifted the prevailing selection pressures: Traits that were adaptive in the old environment could become maladaptive in the new one, and novel morphological traits could be favored if they gave a higher probability of survival and reproduction. The ancestors of the great apes stayed in the forest and, therefore, remained more similar to other primates.

The savanna scenario has lost some of its appeal since paleoenvironmental reconstructions started to show that the environmental setting has been more complex than was originally thought. Accordingly, more recent accounts describe the environment of early human ancestors as a mosaic of woodlands, savanna, and water bodies with considerable temporal fluctuations between climatically arid and wet periods (Bender et al., 2012 ; Domínguez‐Rodrigo, 2014 ; Kingston, 2007 ; Kovarovic & Andrews, 2007 ; Maslin & Christensen, 2007 ). Environmental variability itself has also been proposed to have selected for versatility of adaptations (Potts, 1998a , b ).

There have been different views on which aspects of terrestrial life would have required the morphological changes that the human lineage has experienced, so a large number of different explanations have been put forward for each trait. For example, the origin of the bipedal gait has been attributed to (among other things) gaining better visibility over the savanna grass (Ravey, 1978 ), reaching for food on low branches (Hunt, 1994 , 1996 ), collecting small food items from the ground (Jolly, 1970 ; Kingdon, 2003 ), exposing a smaller part of the body to the scorching sun (Wheeler, 1984 , 1991 ), allowing more energy‐efficient long‐distance travel (Carrier et al., 1984 ; Pontzer, Raichlen, & Sockol, 2009 ; Rodman & McHenry, 1980 ), and freeing the hands to carry food, tools, weapons, or babies (Bartholomew & Birdsell, 1953 ; Hewes, 1961 ; Lovejoy, 1981 ; Sutou, 2012 ; Washburn, 1960 ). It has also been proposed that bipedalism originated already in the trees for hand‐supported walking on small branches too weak for brachiation (Crompton, Sellers, & Thorpe, 2010 ; Thorpe, Holder, & Crompton, 2007 ).

Another adaptationist proposal is that the human ancestors moved from the trees to the waterside, and started to adapt to a partly aquatic way of life (Hardy, 1960 ; Morgan, 1982 ; Verhaegen, Puech, & Munro, 2002 ). This would have exposed them to similar selection pressures than semi‐aquatic mammals, rather than to selection pressures typically experienced by other primates. Under this scenario, bipedal gait would have emerged because it allowed wading to deeper water and made the body more streamlined when swimming and diving for food (Kuliukas, 2002 ; Morgan, 1990 ; Niemitz, 2010 ; Verhaegen et al., 2002 ).

Not all traits need to have originated to enhance survival, however, and critical voices have been raised against interpreting all uniquely human traits as adaptations driven by natural selection (Gee, 2013 ). Sexual selection is known to have produced spectacular new traits in various animals, typically ornaments whose sole purpose is to attract the attention of the opposite sex. These confer no survival advantage or may even be harmful to the bearer. At least human bipedalism, nakedness, and subcutaneous fat layer have been explained by this mechanism (Barber, 1995 ; Giles, 2011 ; Tanner, 1981 ). Especially in small populations, traits may even emerge due to chance fixation of random variation (Sutou, 2012 ).

For someone interested in the “why” of human evolution, it is currently hard to find a comprehensive account of the scientific state of the art. Journal articles typically address only one or a few hypotheses in isolation of the others and often their focus is more on “how” than on “why” a given trait originally emerged (e.g., Crompton et al., 2010 ; Cunnane & Crawford, 2014 ; Isler & Van Schaik, 2014 ; Stout & Chaminade, 2012 ; Watson, Payne, Chamberlain, Jones, & Sellers, 2008 ; Wells, 2006 ). Only proponents of the aquatic/waterside hypotheses (collectively known as the aquatic ape hypothesis or AAH) seem to maintain that it is possible to explain most of the uniquely human traits as adaptive responses to a specific external factor (e.g., Morgan, 1997 ; Vaneechoutte, Kuliukas, & Verhaegen, 2011 ), but these views have found little resonance in paleoanthropological journals (Bender et al., 2012 ). Indeed, AAH has been fiercely opposed and criticized for being an umbrella hypothesis that attempts to explain everything, for being unparsimonious, for lacking evidence and even for being pseudoscience (Hawks, 2005 ; Langdon, 1997 ; Moore, 2012 ).

Here, we aim to find out what scientists really think about why some of the most striking human traits have emerged. We do so by analyzing the results of an online survey where scientists were directly asked for their views on the issue.

2. MATERIALS AND METHODS

2.1. survey.

A survey was performed using an online form in early 2013. Invitation to participate in the survey was sent by email to the authors of articles and review papers that had been published in a scientific journal of a relevant field during the three previous years (2010–2012). A 3‐year period was thought to be long enough for most researchers to have published at least one scientific paper, but short enough for most of the email addresses given in those papers not to have become obsolete. The focus was on journals of paleontology, zoology, ecology, evolutionary biology, and human biology. Only journals with an ISI impact factor equal to or larger than 1.0 were considered. The exact criteria used to select the journals, as well as a full list of journal names, can be found in Appendix S1 .

Almost 58,000 unique email addresses were found in the information available online for the papers published in the selected journals during the selected time period. The full address list exceeded the capacity of the online survey system (Webropol), so the addresses were sorted in alphabetical order, and an invitation to participate in the survey was sent to the first 29,000 addresses. The remaining addresses were used for a different survey, whose results will be reported elsewhere. The first page of the online survey informed participants about the purpose of the survey. The survey was performed anonymously, and all who responded did so voluntarily. After a few reminders had been sent, a total of 1,266 persons had submitted their responses to the survey.

Although the initial sample was large and can be considered representative of the scientific community in relevant fields, the proportion of invitees who answered the survey was very small (4.4%). The sample is no doubt biased toward people who have a larger than average interest in human evolution. Therefore, the obtained answers do not reflect the opinions of the entire scientific community. Nevertheless, they can indicate whether any of the hypotheses proposed to explain the evolutionary origin of a specific human trait is universally accepted or rejected. Even if this were not the case, the survey gives indication of which hypotheses are most or least popular, although conclusions in this respect remain tentative.

The survey first asked background information of the respondent, such as gender, age, the highest academic degree obtained, number of scientific publications authored (both overall and on human evolution), degree of knowledge about human evolution, and whether the respondent has taught courses on human evolution. The second part listed fifteen human traits (such as bipedalism) and asked the respondents to rate the credibility of 51 alternative hypotheses that have been proposed to explain their evolutionary origin (such as freeing the hands for tool use or seeing over tall grass). The credibility scoring was done using a five‐point scale: very unlikely, moderately unlikely, no opinion, moderately likely, and very likely. The number of alternative hypotheses considered was ten for both bipedalism and brain size, eight for hairlessness, seven for speech, four for subcutaneous fat, and three for descended larynx. In addition, there were nine traits for which only one explanation has been proposed in the literature, and this was related to the aquatic ape hypothesis. The third part asked about the respondents’ views on criticism against AAH. All questions and a summary of the answers are presented in Appendix S2 .

2.2. Data analyses

The respondents were asked for their professional field of expertise by offering 15 alternatives. For statistical analyses, these were simplified to four categories to ensure sufficient sample size in each. The group “(paleo)anthropologist” was formed by lumping the originally separate fields “paleoanthropology” and “anthropology or archaeology.” The group “biologist” was formed by lumping all the original subfields of biology (animal physiology, anatomy, or morphology; ecology; evolution; genetics or molecular biology; other) and the group “human biologist” by lumping all subfields of human biology (cardiovascular or respiratory system, musculoskeletal system, nervous system, nutrition, other aspects of human biology). The fourth group was “other,” which contained the remaining fields (geology, paleontology, other).

Overall relationships among the hypotheses were visualized by principal coordinates analysis (PCoA), where the objects were the hypotheses and the descriptors were individual respondents, with the variable of interest being the credibility score each respondent had given to each hypothesis. A Euclidean distance matrix was calculated, such that the distance between two hypotheses reflects how differently the respondents scored their credibilities. Every respondent who gave one of the hypotheses a higher score than the other increased the final distance between the hypotheses, with the overall distance between the hypotheses equaling zero if every respondent had scored both hypotheses similarly (irrespective of whether the score itself was high or low). PCoA visualizes these pairwise distances, so the closer together two hypotheses get plotted in the ordination diagram, the more similar their explanatory value is in the opinion of an average individual respondent.

The respondents themselves were plotted in the PCoA ordination space on the basis of the scores they had given to the hypotheses. Therefore, the relative positions of the respondents reflect their opinions on the hypotheses: Respondents get plotted toward the same part of the ordination space as the hypotheses they gave highest credibility scores, and far away from the hypotheses they gave lowest scores.

Relationships between the respondents’ opinions and their backgrounds were first assessed visually with the help of the ordination diagram. We then used analysis of variance to test whether there were differences in the average opinions of respondents of different backgrounds. If so, a post hoc Tukey's honest significance test was carried out to assess which aspects of the respondents’ background were associated with differences in opinion. A more detailed breakdown of the respondents’ opinions was obtained by visually comparing the distributions of the credibility scores given to the different hypotheses. This was done both to obtain an idea of which hypotheses are most popular overall, and to see if there were differences among respondents representing different scientific fields and/or having different levels of scientific experience.

R statistical software version 3.3.2 ( https://cran.r-project.org/ ) was used both to run the analyses and to produce the graphs. The vegan package (Oksanen et al., 2015 ) was used for principal coordinates analysis. The survey data and all R code used to manipulate and analyze the data are available at Opasnet web‐workspace http://en.opasnet.org/w/Evolutionary_origin_of_human_traits . The survey data are also available from the Dryad Digital Repository https://doi.org/10.5061/dryad.s9r98 .

Principal coordinates analysis revealed some clear patterns among the hypotheses proposed to explain the evolutionary origin of specific human traits. The most eye‐catching feature of the ordination diagram in Figure  2 a is that the hypotheses got divided into two elongated groups that parallel each other but are clearly separated (the abbreviations of Fig. ​ Fig.2 2 are explained in Table  1 ). The smaller group contains all the hypotheses that evoke adaptation to swimming or diving as an explanatory factor for the emergence of a trait, and the larger group contains all other hypotheses, whether they refer to adaptation to a specific environment or to needs that emerge from a specific behavior. Because all the hypotheses in the smaller group refer to locomotion in water and have been included in the aquatic ape hypothesis (AAH), this group will be referred to as the water‐related or AAH group. For lack of a better unifying term, the larger group will be referred to as the dryland group.

Principal coordinates analysis ( PC oA) of different hypotheses proposed to explain the evolutionary origin of specific human traits. Distances between hypotheses are based on scores given by (a) all respondents, or only respondents whose main field of expertise is (b) anthropology or paleoanthropology, (c) biology, (d) human biology, or (e) other. Each colored point corresponds to one hypothesis, and the color indicates which of the traits listed in the inset the hypothesis aims to explain. Points are scaled to reflect the average credibility score given to the corresponding hypothesis by the respondents of the mentioned expertise group. The hypothesis name abbreviations are explained in Table  1 . Each gray point in (a) corresponds to one respondent, whose position within the ordination space reflects the scores given to the hypotheses. For example, respondents plotted toward the bottom left part of the respondent cloud found the hypotheses plotted toward the bottom left of the hypothesis cloud more credible than the hypotheses at the top, and vice versa. More details on the respondent ordination are shown in Figure  3

The hypotheses on the evolutionary origin of human traits that were included in an online survey to find out how popular they are among scientists. The abbreviations are used in the figures, and the full text is copied verbatim from the survey. If ambiguous, the abbreviated hypothesis is followed by a letter depicting the trait: B = bipedalism, E = encephalization (big brain), F = subcutaneous fat, N = nakedness, L = descended larynx, S = speech, O = other

Within each of the two groups, the hypotheses got sorted by their popularity, with the average credibility score increasing toward the bottom left in Figure  2 a. A tight cluster at the extreme left of the dryland group was formed by five hypotheses with high average credibility scores (4.08–4.26 on a 1–5 scale, with 1 corresponding to “very unlikely” and 5 to “very likely”). This cluster included the most popular hypothesis for the subcutaneous fat layer (energy reserve especially for the developing brain), the descended larynx (required by articulate speech), bipedalism (use of tools and weapons), speech (social pressure for elaborate communication), and the big brain (complex social organization).

This combination might be the most popular overall scenario for the origin of these traits, but the next most popular 2–3 explanations for bipedalism (freeing hands for foraging, better view over tall grass), large brain (required by either language or collaborative hunting), and speech (required by either collaborative hunting or transmitting cultural tradition; triggered by the descended larynx) also received high average credibility scores (3.53–3.96). Their proximity in ordination space indicated that they were found credible by the same respondents, which makes it difficult to identify a single most popular overall scenario. The hypotheses explaining hairlessness were not found convincing by the respondents, as even the two most popular ones (avoidance of overheating when hunting, avoidance of ectoparasites) had average credibility scores of only 3.48 and 3.17, respectively.

Eleven of the twelve most popular hypotheses were based on inherent drivers of evolution, that is, proposing that morphological traits emerged in response to selection pressure either from a novel behavior or from a pre‐existing morphological trait. Hypotheses based on selection pressure from a new kind of external environment were less popular even within the dryland group, and the credibility scores of all the hypotheses in the water‐related group were low to intermediate (2.26–2.99). The hypotheses proposing that encephalization was triggered by improved nutrition also received intermediate popularity scores, whether achieved by cooking or by increased consumption of fish or meat (all three with credibility scores in the range 2.61–2.77). The four least popular hypotheses of all (credibility scores 1.95–2.20) were based on inherent drivers operating on dry land.

The ordination results suggest that the respondents viewed the water‐related hypotheses as an ensemble whose overall credibility they assessed independently of how they scored the credibilities of the other hypotheses. This impression is strengthened when viewing the ordination of the respondents (the gray cloud in Figure  2 a) in more detail (Figure  3 ). The main gradient among the respondents follows the average credibility score they gave for the water‐related hypotheses (Figure  2 a), and this is almost perpendicular to the (less clear) gradient of average credibility scores given for the twelve most popular hypotheses (Figure  3 b).

The positions of the survey respondents in the space of the principal coordinates analysis shown in Figure  2 a. The ordination is the same in each panel, but colors illustrate different kinds of information related to each respondent. The colored crosses indicate the mean position of the respondents belonging to the respective subgroup. (a) Average credibility score given to the hypotheses in the water‐related group (the smaller cloud of points in Figure  2 a). (b) Average score given to the 12 most popular hypotheses in Figure  2 a. (c) Number of scientific publications authored or co‐authored (crosses of all three categories overlap). (d) Field of expertise. (e) Familiarity with hypotheses on human evolution. (f) Experience in teaching human evolution

The respondents’ position in the ordination did not seem to be related with how much scientific experience they had in general, as measured with the total number of scientific publications they had authored (Figure  3 c), but it was related with how much they knew about human evolution. Those having more background information on this specific topic (by self‐assessment, by main field of expertise being paleoanthropology or anthropology, or by having taught university courses on the topic) appeared to be more often plotted in the upper part of the ordination than respondents representing other backgrounds (Figure  3 d–f).

The visual impressions were confirmed by statistical analyses. These were carried out separately for five different subgroupings of the hypotheses. Three of these were chosen because they formed clear groups in the ordination of Figure  2 a (the dryland hypotheses, the water‐related hypotheses, the 12 most popular dryland hypotheses). The dryland hypotheses were also split into those based on environmental adaptation and those evoking behavioral drivers.

The largest effect by far on the responses was that of the field or expertise, with (paleo)anthropologists being more critical overall than representatives of any other expertise group (Table  2 ). The difference was especially large for the water‐related hypotheses: The average credibility score given by (paleo)anthropologists to this group of hypotheses (2.10 on the 1–5 scale) was much lower than the average score given by human biologists (3.02), with biologists (2.70), and others (2.67) being intermediate. For the dryland hypotheses, the difference between (paleo)anthropologists (2.97) and human biologists (3.22) was only 0.25 (vs. 0.92 in the case of the water‐related hypotheses), and the differences in the scores given by biologists, human biologists, and others were not statistically significant.

Results of Tukey's HSD test between different subgroups of respondents (line starting with Test result ~) and their average credibility scores (standard deviation in parentheses) for different groups of hypotheses: the most popular 12 hypotheses; the dryland hypotheses (the larger hypothesis group in Figure 2a); the water‐related hypotheses (the smaller hypothesis group in Figure 2a); dryland hypotheses based on behavioural demands; dryland hypotheses based on adaptation to the external environment

The results obtained with respondent subgroups based on total number of authored peer reviewed publications and total number of authored popular science publications are not shown, because they were not associated with significantly different ( p  < .05) means in any comparisons.

*** p  < .001; ** p  < .01; * p  < .05.

Overall scientific experience (as measured with the number of scientific publications authored) had no effect on the scores given to either the dryland or the water‐related hypotheses (Table  2 ). However, the more knowledge the respondents had on human evolution specifically (self‐assessed familiarity with the hypotheses, number of scientific publications on human evolution or experience in teaching human evolution), the lower the scores they gave to the water‐related hypotheses. Among biologists, those who knew more about human evolution were more critical than the less knowledgeable ones, and (paleo)anthropologists were more critical than human biologists with the same self‐assessed knowledge level.

When the dryland hypotheses were split into two groups depending on whether they were based on behavioral arguments or environmental adaptation, both groups obtained rather similar results. The main difference was that the behavioral hypotheses received somewhat higher average credibility scores, which reflects the fact that 10 of the 12 most popular hypotheses were based on behavior (on the other hand, so were the four least popular hypotheses).

To visualize the differences in opinion among the (paleo)anthropologists and representatives of other fields, we repeated the ordination of the hypotheses for each of the four respondent groups separately. In accordance with the fact that most respondents were biologists, the ordination based on the biologists’ data only (Figure  2 c) was very similar to the ordination based on all respondents (Figure  2 a). The ordination based on (paleo)anthropologists’ views (Figure  2 b) differed especially in relation to the hypotheses for bipedalism: Hypotheses that explained bipedalism by foraging, tool use, or carrying were very far removed from the main cloud and toward the opposite side than the water‐related hypotheses. In addition, the average credibility scores given to the water‐related hypotheses were among the lowest of any hypotheses. This contrasted with the situation in the ordination based on human biologists’ data (Figure  2 d), in which the water‐based hypotheses had intermediate credibility scores.

The hypotheses differed clearly from each other in the frequencies of different credibility scores, but there were some similarities in the overall pattern among those six traits for which three or more hypotheses were evaluated (Figure  4 ). None of the hypotheses received the “very likely” score from more than 46% of the respondents, but most traits had at least one hypothesis that was considered “very likely” by more than 23% and likely (either “very likely” or “moderately likely”) by 72%–90%. Many of the intermediately popular hypotheses divided the respondents rather evenly between those who found them likely and those who found them unlikely (the latter referring to the scores “very unlikely” and “moderately unlikely” combined).

Credibility scores given by survey respondents to hypotheses that aim to explain the evolutionary origin of specific human traits. The hypotheses are sorted in order of decreasing popularity as estimated by the percentage of respondents who scored them likely (i.e., either “very likely” or “moderately likely”). Descriptions of the hypotheses as they were given in the survey are shown in Table  1

A causal relationship between articulate speech and descended larynx was accepted by most respondents, but there was no consensus on the direction of the causality. That the larynx descended because this was required by articulate speech was found likely by 84% and very likely by 43%. At the same time, that the evolution of speech was triggered by the descended larynx was found likely by 61% and very likely by 18%. In fact, 36% of the respondents scored both directions as equally likely.

Traits in the category “other” had only one explanatory hypothesis each in the survey, and this was water‐related. All of these hypotheses received many more “very unlikely” than “very likely” scores. However, four hypotheses (that baby swimming, profuse sweating, diving ability, and magnitude of diving reflex evolved as adaptations to a semi‐aquatic way of life) received so many “moderately likely” scores that the percentage of respondents who found them likely was slightly larger than the percentage who found them unlikely (Figure  4 ).

Details on how the hypotheses were scored by respondents representing different fields of expertise are shown in Figure  5 . In accordance with the statistical test results, most hypotheses received rather similar scores from respondents of all fields of expertise. However, (paleo)anthropologists were clearly more critical than representatives of the other fields in relation to several hypotheses, including: that nakedness evolved to avoid ectoparasites, that the big brain evolved because warfare caused pressure for higher intelligence, and that any traits evolved as adaptations to swimming or diving.

Frequencies of credibility scores given to hypotheses aiming to explain different traits (columns) by respondents of different fields of expertise (rows). In each panel, the answers are, from left to right, “very likely,” moderately likely,” “no opinion,” “moderately unlikely,” and “very unlikely.” Hypotheses that have been included in the aquatic ape hypothesis are shown in shades of blue and green. Those dryland hypotheses for which the opinions of anthropologists and other expertise groups clearly diverged are shown in magenta. The other hypotheses are in shades of brown, with darker colors given to hypotheses that received higher average credibility scores in the survey

There was a lot of variation among the traits in how many of the proposed explanations the respondents found convincing (Figure  6 ). For any one trait, 33%–64% of the respondents did not find any of the proposed hypotheses “very likely,” while 19%–38% found exactly one and 8%–45% more than one. Ten respondents (0.8%) explained that they did not score any of the hypotheses as likely, because they do not believe that humans have evolved at all (most of them explicitly referred to special creation by God).

The number of hypotheses (colors) proposed to explain each human trait (rows) that each respondent found very likely (left panel) or likely (either very likely or moderately likely; right panel). The total number of hypotheses included in the survey is shown after the name of each trait

The survey asked respondents’ opinions on twenty critical arguments that have been presented against the aquatic ape hypothesis. For most arguments, the modal response was “no opinion,” especially among those 43% of the respondents who had never heard of AAH before. Nevertheless, some arguments were clearly more frequently agreed with than others (Figure  7 and Table  3 ). The most widely accepted critique was that not all aquatic mammals have naked skin, so hairlessness cannot be considered an aquatic adaptation. In the other extreme, less than 3% of the respondents fully agreed and less than 12% mostly agreed with the critique that AAH is unscientific or not worthy of attention for the reasons given; in most cases, the number of respondents who strongly disagreed with these critiques was larger than the number who mostly or fully agreed.

The degree to which respondents representing different expertise fields agree with critique presented against the aquatic ape hypothesis. The full description of each point of critique can be found in Table  3

Points of critique presented against the aquatic ape hypothesis (AAH). The abbreviations are used in Figure  7 , and the full text is copied verbatim from the survey

4. DISCUSSION

The main results of our survey can be summarized as follows: (1) There was no general agreement among the respondents on why any of the uniquely human traits have evolved: None of the proposed hypotheses was universally either accepted or rejected. (2) For any individual trait, the percentage of respondents who found none of the hypotheses “very likely” was between >30% (bipedalism) and >65% (nakedness). (3) In general, opinions on the credibility of the hypotheses were independent of a person's background (gender, age, field of expertise, degree of scientific experience), but (paleo)anthropologists were clearly more critical than representatives of other fields. (4) The hypotheses that mention adaptation to swimming or diving as an explanatory factor were found much less credible by (paleo)anthropologists and slightly more credible by human biologists than by biologists and representatives of other fields. (5) Most respondents were critical about the aquatic ape hypothesis (AAH), but only a small minority considered it to be unscientific.

Of course, all conclusions based on the survey data must be considered tentative only, because the response rate was very low, and it is possible that the results are biased. Members of some subgroup might have been more likely to respond than members of some other subgroup, and the average credibility scores given to the different hypotheses by the respondents may not be representative of the opinions of all scientists in the background population. However, it is unlikely that a lack of general agreement on the drivers of trait evolution or such a clear difference in opinion between (paleo)anthropologists and others could have emerged just as a result of biased sampling.

Our results did not reveal a set of explanations that would collectively provide a coherent and popular scenario for the origin of all (or even many) human traits. Indeed, some of the hypotheses that had almost equal and rather high average credibility scores explained the same trait, whereas for other traits, no hypothesis emerged as particularly popular. Against this background, it is interesting that almost half of the respondents fully or mostly agreed with the statement that the aquatic ape hypothesis “is not needed, because all human traits can be explained by terrestrial scenarios”.

The lack of agreement on why humans evolved the traits we have today is very obvious in our results: No hypothesis was universally accepted, and for most traits, there were several almost equally popular alternative hypotheses rather than one that would generally be considered superior to the others. None of the hypotheses received the score “very likely” from more than half of the respondents or obtained an average credibility score higher than 4.26 (of 5). For hairlessness, the most popular hypothesis was thought to be “very likely” by only 16% of the respondents, and its average credibility score (3.48) was closer to 3 (which is the limit between being considered more likely than unlikely) than to 4 (moderately likely). In addition, for only two of the traits (subcutaneous fat layer and descended larynx), the most popular hypothesis was found at least moderately likely by almost all respondents at the same time as the next most popular hypothesis was found clearly less likely. This may partly reflect the fact that fewer alternative hypotheses have been proposed for these traits than for many of the others included in the survey.

Importantly, lack of agreement did not reflect just ignorance on the topic among nonspecialists, because the responses were, in general, very similar between anthropologists and respondents representing other fields of science. In fact, anthropologists were even more skeptical about all hypotheses than representatives of the other fields were. In other words, outsiders were slightly more convinced that the proposed hypotheses are plausible than those who work in the field. Maybe anthropologists (especially paleoanthropologists) are more systematically trained to be wary of just‐so‐stories (explanations of past events and processes backed up by little or no evidence) than students in nearby fields are. It is also possible that outsiders are somewhat less likely to question hypotheses proposed within an unfamiliar field. This could be because they do not feel qualified to do so, or because they have not heard of the debates that draw attention to the weaknesses of the hypotheses.

Our results conform with the widespread belief that professionals in the field of human evolution are more critical toward the aquatic ape hypothesis (AAH) than outsiders are (Langdon, 1997 ; Bender et al., 2012 ; see also nonscientific sources such as Hawks, 2005 ; Moore, 2012 and Wikipedia: Aquatic Ape Hypothesis: Talk). However, this did not seem to be due to overall scientific ignorance, because how respondents assessed the credibility of the hypotheses proposing adaptation to swimming or diving was independent of both their overall scientific experience level and how they assessed the credibility of the other hypotheses. Interestingly, those whose main field of expertise is human biology had the most positive attitudes toward the water‐related hypotheses, giving them an average credibility score that was as much as 0.9 units higher (on a 1–5 scale) than the average score given by (paleo)anthropologists.

The difference in average opinion between (paleo)anthropologists and other scientists can be interpreted in two opposite ways. On the one hand, those who know the field of human evolution best may be best positioned to make a justified evaluation of the validity of the alternative hypotheses. On the other hand, prior knowledge may induce one to reject unconventional hypotheses offhand merely because they challenge the established paradigms of a field (Bender et al., 2012 ; Klayman, 1995 ). Obviously, the two interpretations lead to opposite conclusions on whether or not the critical attitude of the (paleo)anthropologists can be taken as evidence that AAH is flawed. In our survey, a vast majority of the respondents who had an opinion on the issue disagreed with the statement that AAH can be ignored because its main proponents are not professionals in the field of human evolution. This was the case both overall and within each field of expertise separately, although the proportion of respondents who agreed with the statement was higher among (paleo)anthropologists than among representatives of the other fields.

In this context, it is also interesting that the respondents’ assessment of the credibility of the water‐related hypotheses did not depend on the number of scientific papers they had authored. This indicates that established scientists are no more likely to reject or accept these hypotheses than junior scientists are—unless their scientific experience relates directly to the field of human evolution. A vast majority of the respondents disagreed with the critique that AAH is unscientific. Of course, this does not mean that they would consider the explanations proposed by AAH to be correct, and indeed, all the hypotheses related to AAH received relatively low credibility scores (although not as low as the least popular dryland hypotheses).

If, for the sake of argument, we accept the most popular explanation for each trait to be the correct one, a scenario of evolution by internal drive emerges: The large brain evolved because complex social organization required higher intelligence, the subcutaneous fat layer evolved to serve as an energy reserve for the developing brain, articulate speech evolved because there was social pressure for elaborate communication, the larynx descended because this was required by articulate speech, bipedalism evolved to make the use of tools and weapons easier, and nakedness evolved to avoid overheating when hunting. For most traits, the next most popular explanation was not far behind in popularity. Most of these were also based on inherent drivers, but sometimes in the opposite temporal sequence (e.g., articulate speech was triggered by the descended larynx; large brain evolved because it was required by articulate speech). We found this result disturbing, because the overwhelming popularity of hypotheses based on inherent drivers gives the impression that human evolution is generally thought to have been goal‐directed. This would be in conflict with the current understanding (explained in every evolutionary biology textbook) that evolution has no foresight.

Overall, the survey revealed no general agreement among the respondents: None of the proposed hypotheses on why specific uniquely human traits have evolved was universally either accepted or rejected. Nevertheless, identifying and quantifying what is not generally known and agreed upon can be useful in itself, as it may help to focus future research on answering the most important open questions. Clearly, there is still a long way to go before the question “why are humans so different from other primates” has been answered in a comprehensive and generally satisfactory way.

DATA ACCESSIBILITY

Conflict of interest.

None declared.

AUTHOR CONTRIBUTIONS

HT designed and conducted the survey and led the writing. All authors discussed the results and planned the data analyses together. The R code used to analyze the data and draw the figures was written by MT with contributions from JT.

Supporting information

Acknowledgments.

We thank Carlos Peña for writing the code to extract respondents’ email addresses from the Internet; Mirkka Jones, Kalle Ruokolainen, and Timo Vuorisalo for comments that helped to improve the survey questions; and Jouko Tuomisto for comments on the manuscript.

Tuomisto H, Tuomisto M, Tuomisto JT. How scientists perceive the evolutionary origin of human traits: Results of a survey study . Ecol Evol . 2018; 8 :3518–3533. https://doi.org/10.1002/ece3.3887 [ PMC free article ] [ PubMed ] [ Google Scholar ]

• Barber, N. (1995). The evolutionary psychology of physical attractiveness: Sexual selection and human morphology . Ethology and Sociobiology , 16 , 395–424. https://doi.org/10.1016/0162-3095(95)00068-2 [ Google Scholar ]
• Bartholomew, G. A. , & Birdsell, J. B. (1953). Ecology and the Protohominids* . The American Anthropologist , 55 , 481–498. [ Google Scholar ]
• Bender, R. , Tobias, P. W. , & Bender, N. (2012). The savannah hypotheses: Origin, reception and impact on paleoanthropology . History & Philosophy of the Life Sciences , 34 , 147–184. [ PubMed ] [ Google Scholar ]
• Carrier, D. R. , Kapoor, A. K. , Kimura, T. , Nickels, M. K. , Scott, E. C. , So, J. K. , & Trinkaus, E. (1984). The energetic paradox of human running and hominid evolution [and comments and reply] . Current Anthropology , 25 , 483–495. https://doi.org/10.1086/203165 [ Google Scholar ]
• Crompton, R. H. , Sellers, W. I. , & Thorpe, S. K. S. (2010). Arboreality, terrestriality and bipedalism . Philosophical Transactions of the Royal Society B: Biological Sciences , 365 , 3301–3314. https://doi.org/10.1098/rstb.2010.0035 [ PMC free article ] [ PubMed ] [ Google Scholar ]
• Cunnane, S. C. , & Crawford, M. A. (2014). Energetic and nutritional constraints on infant brain development: Implications for brain expansion during human evolution . Journal of Human Evolution , 77 , 88–98. https://doi.org/10.1016/j.jhevol.2014.05.001 [ PubMed ] [ Google Scholar ]
• Dart, R. (1925). Australopithecus africanus : The man‐ape of South Africa . Nature , 115 , 195–199. https://doi.org/10.1038/115195a0 [ Google Scholar ]
• Domínguez‐Rodrigo, M. (2014). Is the “Savanna Hypothesis” a dead concept for explaining the emergence of the earliest hominins? Current Anthropology , 55 , 59–81. https://doi.org/10.1086/674530 [ Google Scholar ]
• Gee, H. (2013). The accidental species: Misunderstandings of human evolution . Chicago, IL: University of Chicago Press; https://doi.org/10.7208/chicago/9780226044989.001.0001 [ Google Scholar ]
• Giles, J. (2011). Naked love: The evolution of human hairlessness . Biology Theory , 5 , 326–336. [ Google Scholar ]
• Hardy, A. (1960). Was man more aquatic in the past? The New Scientist , 7 , 642–645. [ Google Scholar ]
• Hawks, J. (2005). Why anthropologists don't accept the Aquatic Ape Theory . Retrieved from http://johnhawks.net/weblog/topics/pseudoscience/aquatic_ape_theory.html [accessed 5 September 2017]
• Hewes, G. W. (1961). Food transport and the origin of hominid bipedalism . The American Anthropologist , 63 , 687–710. https://doi.org/10.1525/aa.1961.63.4.02a00020 [ Google Scholar ]
• Hunt, K. D. (1994). The evolution of human bipedality: Ecology and functional morphology . Journal of Human Evolution , 26 , 183–202. https://doi.org/10.1006/jhev.1994.1011 [ Google Scholar ]
• Hunt, K. D. (1996). The postural feeding hypothesis: An ecological model for the evolution of bipedalism . South African Journal of Science , 92 , 77–90. [ Google Scholar ]
• Isler, K. , & Van Schaik, C. P. (2014). How humans evolved large brains: Comparative evidence . Evolutionary Anthropology: Issues, News, and Reviews , 23 , 65–75. https://doi.org/10.1002/evan.21403 [ PubMed ] [ Google Scholar ]
• Jolly, C. J. (1970). The seed‐eaters: A new model of hominid differentiation based on a baboon analogy . Man , 5 , 5–26. https://doi.org/10.2307/2798801 [ Google Scholar ]
• Kingdon, J. (2003). Lowly origin: Where, when, and why our ancestors first stood up . Princeton, NJ: Princeton University Press. [ Google Scholar ]
• Kingston, J. D. (2007). Shifting adaptive landscapes: Progress and challenges in reconstructing early hominid environments . The American Journal of Physical Anthropology , 134 , 20–58. https://doi.org/10.1002/(ISSN)1096-8644 [ PubMed ] [ Google Scholar ]
• Klayman, J. (1995). Varieties of confirmation bias In Busemeyer J., Hastie R., & Medin D. L. (Eds.), Psychology of learning and motivation (pp. 385–418). Cambridge, MA: Academic Press. [ Google Scholar ]
• Kovarovic, K. , & Andrews, P. (2007). Bovid postcranial ecomorphological survey of the Laetoli paleoenvironment . Journal of Human Evolution , 52 , 663–680. https://doi.org/10.1016/j.jhevol.2007.01.001 [ PubMed ] [ Google Scholar ]
• Kuliukas, A. (2002). Wading for food the driving force of the evolution of bipedalism? Nutrition and Health , 16 , 267–289. https://doi.org/10.1177/026010600201600402 [ PubMed ] [ Google Scholar ]
• Langdon, J. H. (1997). Umbrella hypotheses and parsimony in human evolution: A critique of the Aquatic Ape Hypothesis . Journal of Human Evolution , 33 , 479–494. https://doi.org/10.1006/jhev.1997.0146 [ PubMed ] [ Google Scholar ]
• Leakey, R. , & Lewin, R. (1977). Origins: The emergence and evolution of our species and its possible future . Boston, MA: E. P. Dutton. [ Google Scholar ]
• Lovejoy, C. O. (1981). The origin of man . Science , 211 , 341–350. https://doi.org/10.1126/science.211.4480.341 [ PubMed ] [ Google Scholar ]
• Maslin, M. A. , & Christensen, B. (2007). Tectonics, orbital forcing, global climate change, and human evolution in Africa: Introduction to the African paleoclimate special volume . Journal of Human Evolution , 53 , 443–464. https://doi.org/10.1016/j.jhevol.2007.06.005 [ PubMed ] [ Google Scholar ]
• Moore, J. (2012). Aquatic ape theory: Sink or swim? Retrieved from www.aquaticape.org [accessed 5 September 2017]
• Morgan, E. (1982). The aquatic ape: A theory of human evolution . London, UK: Souvenir Press. [ Google Scholar ]
• Morgan, E. (1990). The scars of evolution: What our bodies tell us about human origins . London, UK: Souvenir Press. [ Google Scholar ]
• Morgan, E. (1997). The aquatic ape hypothesis . London, UK: Souvenir Press. [ Google Scholar ]
• Niemitz, C. (2010). The evolution of the upright posture and gait—a review and a new synthesis . Naturwissenschaften , 97 , 241–263. https://doi.org/10.1007/s00114-009-0637-3 [ PMC free article ] [ PubMed ] [ Google Scholar ]
• Oksanen, J. , Blanchet, F. G. , Kindt, R. , Legendre, P. , Minchin, P. R. , O'Hara, R. B. , … Wagner, H. (2015). Vegan: Community ecology package . R package version 2.3‐2. http://CRAN.R-project.org/package=vegan
• Pontzer, H. , Raichlen, D. A. , & Sockol, M. D. (2009). The metabolic cost of walking in humans, chimpanzees, and early hominins . Journal of Human Evolution , 56 , 43–54. https://doi.org/10.1016/j.jhevol.2008.09.001 [ PubMed ] [ Google Scholar ]
• Potts, R. (1998a). Environmental hypotheses of hominin evolution . The American Journal of Physical Anthropology , 107 , 93–136. https://doi.org/10.1002/(ISSN)1096-8644 [ PubMed ] [ Google Scholar ]
• Potts, R. (1998b). Variability selection in hominid evolution . Evolutionary Anthropology: Issues, News, and Reviews , 7 , 81–96. https://doi.org/10.1002/(ISSN)1520-6505 [ Google Scholar ]
• Ravey, M. (1978). Bipedalism: An early warning system for Miocene Hominoids . Science , 199 , 372 https://doi.org/10.1126/science.199.4327.372 [ PubMed ] [ Google Scholar ]
• Rodman, P. S. , & McHenry, H. M. (1980). Bioenergetics and the origin of hominid bipedalism . The American Journal of Physical Anthropology , 52 , 103–106. https://doi.org/10.1002/(ISSN)1096-8644 [ PubMed ] [ Google Scholar ]
• Stout, D. , & Chaminade, T. (2012). Stone tools, language and the brain in human evolution . Philosophical Transactions of the Royal Society B: Biological Sciences , 367 , 75–87. https://doi.org/10.1098/rstb.2011.0099 [ PMC free article ] [ PubMed ] [ Google Scholar ]
• Sutou, S. (2012). Hairless mutation: A driving force of humanization from a human–ape common ancestor by enforcing upright walking while holding a baby with both hands . Genes to Cells , 17 , 264–272. https://doi.org/10.1111/j.1365-2443.2012.01592.x [ PMC free article ] [ PubMed ] [ Google Scholar ]
• Tanner, N. M. (1981). On becoming human . Cambridge, UK: CUP Archive. [ Google Scholar ]
• Thorpe, S. K. S. , Holder, R. L. , & Crompton, R. H. (2007). Origin of human bipedalism as an adaptation for locomotion on flexible branches . Science , 316 , 1328–1331. https://doi.org/10.1126/science.1140799 [ PubMed ] [ Google Scholar ]
• Vaneechoutte, M. , Kuliukas, A. , & Verhaegen, M. (2011). Was man more aquatic in the past? Fifty years after Alister hardy – Waterside hypotheses of human evolution . Sharjah, UAE: Bentham Science Publishers. [ Google Scholar ]
• Verhaegen, M. , Puech, P.‐F. , & Munro, S. (2002). Aquarboreal ancestors? Trends in Ecology & Evolution , 17 , 212–217. https://doi.org/10.1016/S0169-5347(02)02490-4 [ Google Scholar ]
• Washburn, S. L. (1960). Tools and human evolution . Scientific American , 203 , 62–75. https://doi.org/10.1038/scientificamerican0960-62 [ PubMed ] [ Google Scholar ]
• Watson, J. C. , Payne, R. C. , Chamberlain, A. T. , Jones, R. K. , & Sellers, W. I. (2008). The energetic costs of load‐carrying and the evolution of bipedalism . Journal of Human Evolution , 54 , 675–683. https://doi.org/10.1016/j.jhevol.2007.10.004 [ PubMed ] [ Google Scholar ]
• Wells, J. C. K. (2006). The evolution of human fatness and susceptibility to obesity: An ethological approach . Biological Reviews , 81 , 183–205. https://doi.org/10.1017/S1464793105006974 [ PubMed ] [ Google Scholar ]
• Wheeler, P. E. (1984). The evolution of bipedality and loss of functional body hair in hominids . Journal of Human Evolution , 13 , 91–98. https://doi.org/10.1016/S0047-2484(84)80079-2 [ Google Scholar ]
• Wheeler, P. E. (1991). The influence of bipedalism on the energy and water budgets of early hominids . Journal of Human Evolution , 21 , 117–136. https://doi.org/10.1016/0047-2484(91)90003-E [ Google Scholar ]

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The male Y chromosome in humans is evolving faster than the X. Scientists have now discovered the same trend in six species of primate.

The Y chromosome in primates — including humans — is evolving much more rapidly than the X chromosome, new research on six primate species suggests.

For instance, humans and chimpanzees share upwards of 98% of their DNA across the whole of the genome, but just 14% to 27% of the DNA sequences on the human Y chromosome are shared with our closest living relatives. 

The finding surprised scientists, given that humans and chimpanzees diverged just 7 million years ago — a blip in evolutionary terms.

"I expect my genome to be very different to that of bacteria or insects because a lot of time has elapsed, evolutionarily speaking," study co-author Brandon Pickett , a postdoctoral fellow at the National Human Genome Research Institute (NHGRI) at the National Institutes of Health, told Live Science. "But from other primates, I expect it to be pretty similar."

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It's not clear exactly why the Y chromosome is evolving so rapidly. For starters there is only a single copy of the Y chromosome per cell — in primates, females carry two copies of the X chromosome, while males carry an X and a Y chromosome ––the Y chromosome plays a critical role in sperm production and fertility. Having only a single copy of the Y chromosome presents a vulnerability ––if changes happen to occur, there is no second chromosome to act as a backup. 

And changes are likely to occur due to something called mutation bias. The Y chromosome may be so prone to change because it generates many sperm. This requires lots of DNA replication. And every time DNA is copied, there's a chance for mistakes to creep in. 

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Scientists have previously sequenced the primate genome for all 16 representative families . 

In the new study, published May 29 in the journal Nature , scientists compared the sex chromosomes of five great ape species — chimpanzees ( Pan troglodytes ), bonobos ( Pan paniscus ), western lowland gorillas ( Gorilla gorilla gorilla) and Bornean and Sumatran orangutans ( Pongo pygmaeus and Pongo abelii ) — and one more distantly related to humans, siamang gibbons ( Symphalangus syndactylus ).

The team studied the chromosomes  using telomere-to-telomere (T2T) sequencing. T2T can accurately sequence repetitive elements, including the protective telomere "caps" of chromosomes that have proven difficult to read in the past, Pickett said. The researchers used computing software to make comparisons between the sequencing results, by creating alignments to reveal which parts of the chromosome had changed and which parts had stayed the same.

The chromosomal X and Y sequences of each of the six species were also compared to the human X and Y chromosome, already sequenced in an earlier study with the T2T method. 

The findings revealed that across all the studied species, the Y chromosome evolved rapidly. Even species in the same genus have very different Y chromosomes to one another. For instance, chimpanzees and bonobos diverged just 1 million to 2 million years ago, yet there is a dramatic difference in their Y chromosome lengths, said Christian Roos , a senior scientist at the Primate Genetics Laboratory, German Primate Center, who was not involved in the study.

In some cases the difference in length — caused by chromosome losses or duplications that occur when DNA is copied — amounted to up to about half of the observed differences. For example, the Y chromosome from the Sumatran orangutan is twice as long as the gibbon's Y chromosome.  

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In contrast, the study found that the X chromosome was highly conserved across the primate species, as might be expected for a structure with a critical role in reproduction.  

One reason the Y seems to have thrived despite such a high rate of mutation is that across all the studied species, it contains stretches of highly repetitive genetic material, such as palindromic repeats, where the sequence reads the same forward and backward. Nestled within these stretches of repeating DNA are genes. So the repeated DNA may safeguard important genes from replication mistakes and thereby preserve essential biological material, the researchers wrote in their paper. 

The study did have limitations though; it looked at only a single representative for each primate species, and it couldn't say how much the Y chromosome would vary within animals of the same species, Pickett said. 

Nicola Williams holds a PhD in the History of Science from the University of Leeds, U.K. and currently works as a science writer across an array of subject areas broadly spanning, but not limited to, biology, physics, medicine and technology. 

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ASU study points to origin of cumulative culture in human evolution

Humans began to rapidly accumulate technological knowledge through social learning around 600,000 years ago.

Stone tools that become increasingly more complex over the course of 3 million years. Left: First time period studied — Oldowan core, Koobi Fora, Kenya (below baselines). Center: Second time period studied — Acheulean cleaver, Algeria (around baseline). Right: Characteristic of 600,000 year ago technology — Levallois core, late Pleistocene Algeria. Image credits: (left) Curry, Michael. 2020. Oldowan Core, Koobi Fora. Museum of Stone Tools. Retrieved June 10. From: https://une.pedestal3d.com/r/DGHMTdkn4_; (middle) Curry, Michael. 2020. Acheulean Cleaver, Morocco, Koobi Fora. Museum of Stone Tools. Retrieved June 10. From: https://une.pedestal3d.com/r/JMVajqyz29; (right) Watt, Emma. 2020. Levallois Core, Algeria. Museum of Stone Tools. Retrieved June 10. From: https://une.pedestal3d.com/r/JMVajqyz29.

Each of us individually is the accumulated product of thousands of generations that have come before us in an unbroken line. Our culture and technology today are also the result of thousands of years of accumulated and remixed cultural knowledge.

But when did our earliest ancestors begin to make connections and start to build on the knowledge of others, setting us apart from other primates? Cumulative culture — the accumulation of technological modifications and improvements over generations — allowed humans to adapt to a diversity of environments and challenges. But, it is unclear when cumulative culture first developed during hominin evolution.

A study published this week in the Proceedings of the National Academy of Sciences journal by Arizona State University researcher Charles Perreault and doctoral graduate Jonathan Paige  concludes that humans began to rapidly accumulate technological knowledge through social learning around 600,000 years ago.

“Our species, Homo sapiens, has been successful at adapting to ecological conditions — from tropical forests to arctic tundra — that require different kinds of problems to be solved," said Perreault, a research scientist with the Institute of Human Origins and an associate professor with the School of Human Evolution and Social Change . “Cumulative culture is key because it allows human populations to build on and recombine the solutions of prior generations and to develop new complex solutions to problems very quickly.

"The result is, our cultures — from technological problems and solutions to how we organize our institutions — are too complex for individuals to invent on their own.”

To investigate when this technological turn may have begun and to explore the origin of cumulative culture, Paige and Perreault analyzed changes in the complexity of stone tool manufacturing techniques across the past 3.3 million years of the archaeological record.

As a baseline for the complexity of stone tool technologies achievable without cumulative culture, the researchers analyzed technologies used by nonhuman primates — like chimpanzees — and stone tool manufacturing experiments involving inexperienced human flintknappers and randomized flaking.

The researchers broke down the complexity of the stone tool technologies by the number of steps (procedural units, or PUs) that each tool-making sequence involved.

The results suggested that from around 3.3 to 1.8 million years ago — when australopiths and earliest Homo species were around — stone tool manufacturing sequences remained within the range of the baselines (1 to 6 PUs). From around 1.8 million to 600,000 years ago, manufacturing sequences began to overlap with and slightly exceed the complexity baseline (4 to 7 PUs). But, after around 600,000 years ago, the complexity of manufacturing sequences rapidly increased (5 to 18 PUs).

“By 600,000 years ago or so, hominin populations started relying on unusually complex technologies, and we only see rapid increases in complexity after that time as well. Both of those findings match what we expect to see among hominins who rely on cumulative culture,” said Paige, a postdoctoral researcher at the University of Missouri and an ASU PhD graduate.

Tool-assisted foraging may have been the impetus for the earliest beginning of the evolution of cumulative culture. Early hominins, 3.4 to 2 million years ago, likely relied on foraging strategies that require tools — like accessing meat, marrow and organs — leading to changes in brain size, lifespan and biology that set the stage for cumulative culture.

While other forms of social learning may have influenced tool-making, it is only in the Middle Pleistocene when there is evidence for rapid increases in technological complexity and the development of other kinds of new technologies.

The Middle Pleistocene also shows consistent evidence of controlled use of fire, hearths and domestic spaces, likely essential components of the development of cumulative culture. Other kinds of complex technologies also developed in the Middle Pleistocene, including wooden structures constructed with logs hewn using hafted tools, which are stone blades affixed to wooden or bone handles.

This all suggests that cumulative culture arose near the beginning of the Middle Pleistocene epoch, possibly predating the divergence of Neanderthals and modern humans.

Published article: 3.3 million years of stone tool complexity suggests cumulative culture began during the Middle Pleistocene . Jonathan Paige and Charles Perrealt. Proceedings of the National Academy of Sciences .

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Evolution, as related to genomics, refers to the process by which living organisms change over time through changes in the genome. Such evolutionary changes result from mutations that produce genomic variation, giving rise to individuals whose biological functions or physical traits are altered. Those individuals who are best at adapting to their surroundings leave behind more offspring than less well-adapted individuals. Thus, over successive generations (in some cases spanning millions of years), one species may evolve to take on divergent functions or physical characteristics or may even evolve into a different species.

Evolution. Studying the science of evolution can completely transform our understanding of the subject of history. Evolution is, in a way, the history of all living organisms on Earth. And the timescale for appreciating that history is just so many orders of magnitude greater than what we can understand from the study of human history alone. It's actually humbling to situate human experience against that backdrop of millions of years of gradual change to the genome, millions of years of activity that took place on Earth prior to humans coming onto the scene.

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• The Evolution of Pew Research Center’s Survey Questions About the Origins and Development of Life on Earth

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• Acknowledgments

Have living things always existed in their present form, or did they evolve? And if evolution occurred, was a divine hand at play?

Measuring public opinion on evolution has never been an easy task for survey researchers. With Americans’ views on the topic tapping into the highly charged realms of religious conviction and scientific knowledge, question wording becomes extremely important. For this reason, in recent years, Pew Research Center has experimented with different ways of asking about evolution and studied whether these variations affect the public’s responses. And because they do, the Center is moving toward a revised wording.

First, a bit of survey history: For a decade and a half, the Center asked Americans what they believe about the origins of humankind, most often in a two-step process. An initial question asked respondents whether they think humans and other living things have evolved over time – in line with Charles Darwin’s theory of evolution – or whether they believe humans have existed in their present form since the beginning of time, as in the Book of Genesis’ creation story. Those who said they accept the idea of evolution then have been asked a second question: whether they think evolution has occurred due to natural processes such as natural selection, or due to processes that were guided or allowed by God.

Recently, however, the Center conducted a survey in which respondents were randomly assigned to be asked about evolution in one of two different ways. Half of the respondents were asked about evolution in a two-step process much like the one described above. The other half of respondents were asked a single question about their views on evolution and given three response options: “Humans have evolved over time due to processes such as natural selection; God or a higher power had no role in this process”; “Humans have evolved over time due to processes that were guided or allowed by God or a higher power”; or “Humans have existed in their present form since the beginning of time.”

The data show that respondents in the latter group (those who receive a single question with three options) are more likely than those in the former group to say evolution has occurred. Overall, eight-in-ten in the single-question group say humans have evolved over time (and just 18% say humans have always existed in their present form), while only two-thirds of those who receive the older, two-step approach say humans have evolved (and 31% express the creationist view).

Put more simply, our estimate of the share of Americans who reject evolution and express a creationist view drops considerably (from 31% to 18% of U.S. adults) when respondents are immediately given the opportunity to say God played a role in human evolution. The effect of the different question wording is especially pronounced among white evangelical Protestants and black Protestants.

The experimental findings illustrate why testing multiple ways of asking about evolution is necessary and important. For some people, views about the origins and development of human life are bound up with deeply held religious beliefs. Pew Research Center’s goal in designing questions on this topic is to allow respondents to share their thoughts about both the scientific theory of evolution and God’s role in the creation and development of life on Earth – and to do so in a way that does not force respondents to choose between science and religion. Indeed, the data show that many Americans believe that life on Earth has evolved over time AND that God or a supreme being played some role in the evolutionary process.

In the future, Pew Research Center intends to use this new, three-option approach to asking about evolution in much of its U.S.-based survey research – though the older, two-step approach may continue to work well in certain international contexts (for example, in countries where views about evolution are less closely bound up with religious beliefs than is the case in the U.S.) or for monitoring long-term trends in the United States. The results of the new experiment indicate that there are some people who do believe that humans have evolved over time, but who, for whatever reason, did not say so in our traditional method of asking about the topic. Perhaps without the opportunity to immediately connect evolution to God, some religious respondents may be concerned that expressing belief in evolution places them uncomfortably on the secular side of a cultural divide.

The results of the survey also show that devising survey questions that enable respondents to register nuance in their views about these subjects is very important – and very challenging. Prior to this most recent experiment, the Center tested various versions of the two-step process to asking about evolution. In one line of testing, we varied the survey context (that is, the questions that immediately precede the evolution questions). In another line of testing, we varied whether the questions asked about the evolution of “ humans and other living things” or “ animals and other living things.”

What follows below is a brief history of the way the Center has asked about evolution.

Testing the effect of asking about belief in God

The first time Pew Research Center asked about evolution, in 2005 , the evolution questions were preceded with up to two questions about belief in God. Respondents were asked whether they believe in God, a higher power or universal spirit (but not God), or neither God nor a higher power or universal spirit. Those who said they believe in God or a higher power were asked if they believe that this entity “was responsible for the creation of life on Earth.”

Then, all respondents were asked the following question, which included the wording that would become our core language for evolution questions over the next decade: “Some people think that humans and other living things have evolved over time. Others think that humans and other living things have existed in their present form since the beginning of time. Which of these comes closest to your view?”

[do you think that]

Why begin a survey module about evolution with questions about belief in God? Researchers were concerned that questions about evolution may have become so caught up in contentious debates about religion, culture and politics that simply asking about evolution outright might lead to erroneous results. Religious people who believe both that evolution has occurred and that God played a role in it might nevertheless – when asked cold – choose the creationist option simply as a way of registering their belief that God exists, and not because they truly reject evolution. Without having first been given the chance to stipulate that they believe God exists and played a role in the creation of life on Earth, some respondents may have seen it as socially undesirable to say they believe humans have evolved over time.

Overall, the 2005 survey found that roughly half of U.S. adults said humans have evolved over time, including 26% who said evolution was due to natural processes, and 18% who said it was guided by a supreme being. Four-in-ten said humans have existed in their present form since the beginning of time, and an additional 10% either were not sure or declined to answer the question.

The following year, the Center again explored people’s views on evolution. The 2006 survey included an experimental test of the premise that asking about belief in God would affect respondents’ answers to the ensuing questions on evolution. Half of the survey’s respondents were randomly assigned to receive the belief-in-God questions before the evolution questions, while the other half of respondents did not receive the belief-in-God questions.

Analysis of the data showed that respondents answered the evolution question series similarly, regardless of whether they were first asked about their belief in God. Since the experimental test showed that asking about belief in God had no impact on the way respondents answer questions about evolution, all Pew Research Center surveys conducted since 2006 have omitted the introductory questions measuring beliefs about God.

Hints of greater acceptance of evolution in 2009; subsequent surveys find stable views after 2009

The Center asked a very similar, two-step battery of evolution questions three years later . The survey results appeared to show an increase of 10 percentage points in the share of Americans who say they believe evolution has occurred, from 51% in 2006 to 61% in 2009. However, researchers were concerned that responses to the 2009 question may have been influenced by the fact that the entire 2009 survey was about scientific topics.

Specifically, people who are most interested in scientific topics may have been more likely to participate in the survey. Such individuals may also believe in evolution at higher rates than those who are not so interested in scientific topics, thus inflating the survey’s estimate of the share of the public that believes evolution has occurred.

It is also possible that a slight change to the wording of the question between 2006 and 2009 could have affected the results. In 2005 and 2006, the first question in the series read as follows: “Some people think that humans and other living things have evolved over time. Others think that humans and other living things have existed in their present form since the beginning of time. Which of these comes closest to your view?” Beginning in 2009, the question was simplified to ask “Which comes closer to your view? Humans and other living things have evolved over time, OR humans and other living things have existed in their present form since the beginning of time.” 1  The original wording may have lent equal legitimacy to both viewpoints by telling respondents that there are people on both sides of the debate; this may have nudged some to the creationist response.

As a result of the different survey context and the slight change in question wording, Pew Research Center did not report the 2009 results as the continuation of a trend that began in 2005. Instead, the earlier results were included alongside the 2009 findings only as a “trend for comparison” – as an indication that there may have been some change in sentiment between 2006 and 2009, but without making a direct, apples-to-apples estimate of the magnitude of the change.

Between 2013 and 2014, Pew Research Center asked the two-step evolution question series four more times. On all four occasions, the share of those who said they believe humans have evolved over time fell between 60% and 65%.

Belief in evolution among religious and demographic groups

In the 2014 U.S. Religious Landscape Study (the last telephone survey in which the Center asked the traditional, two-step series of questions about evolution), the data show that belief in evolution is more common among college graduates (73%) than among those with lower levels of educational attainment (62% among those with some college education, 53% among those with a high school diploma or less education). Belief in evolution is also more prevalent among young people (72% among adults under the age of 30) than among older adults (52% among those ages 65 and older), and somewhat more common among men than women (65% vs. 58%).

Among religious groups, belief in evolution peaks among self-described atheists (95% of whom say they believe humans and other living things have evolved over time) and agnostics (96%). Roughly eight-in-ten or more Buddhists (86%), Jews (81%) and Hindus (80%) also say they believe in evolution, as do smaller majorities of Catholics (66%) and mainline Protestants (65%) – though members of these Christian traditions are much more likely than religiously unaffiliated people and members of most non-Christian faiths to say they believe God played a role in guiding the evolutionary process.

Among members of evangelical Protestant denominations, the balance of opinion leans in the opposite direction – 57% of evangelicals said in the 2014 telephone survey that humans and other living things have existed in their present form since the beginning of time, compared with 38% who said they believe humans have evolved over time. And members of historically black Protestant denominations were divided about evenly between those who believe in evolution (50%) and those who do not (45%). Statistical analysis shows that evangelicals and people who belong to historically black Protestant denominations are less likely than those in many other religious groups to believe in evolution even after accounting for different levels of educational attainment.

As noted at the outset of this report, our recent experiment found that including an immediate option to link God to evolution makes a substantial difference in the responses given by white evangelicals and black Protestants. For details, see “ How highly religious Americans view evolution depends on how they’re asked about it .”

Testing beliefs about the evolution of humans vs. the evolution of animals

In 2013, Pew Research Center experimented with the wording of the standard question about evolution. A random group of respondents was asked about the evolution of “ humans  and other living things,” while other respondents were asked about the evolution of “ animals  and other living things.”

The survey found that white evangelical Protestants were more likely to say animals and other living things have evolved over time (41%) than they were to say the same about humans (27%). Among white mainline Protestants, the opposite was true: More said humans evolved (78%) than animals (66%). The experiment found no significant differences in the way black Protestants, Catholics and religiously unaffiliated respondents answered the questions.

Concluding observations

Taken together, the findings presented here show that asking questions about the origin and development of life on Earth can be a complicated undertaking – perhaps especially in a country like the United States, where the public’s attitudes about the scientific theory of evolution often are bound up with their religious convictions. What may seem like small differences in question wording can have a major impact on survey estimates of the share of the public that believes in a naturalistic account of human development, a creationist view or something in between – an evolutionary process guided or at least allowed by God or a supreme being. Pew Research Center has been committed to innovation on these kinds of questions to try to capture public opinion in its full complexity, and the Center will continue to experiment and report the results transparently.

• The order in which response options were read to respondents was randomized in all of the surveys analyzed here. ↩

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Every Single Cell in Your Body Could Be Conscious, Scientists Say. That Could Rewrite Everything We Know About Human Evolution

If trillions of tiny bits of consciousness are floating around inside you, it could change how we think about life.

The reason for such cooperation comes down to a cellular form of intelligence, says evolutionary biologist and physician William B. Miller, Ph.D. He’s co-author of the book, The Sentient Cell: The Cellular Foundations of Consciousness , published in January 2024, which proposes a radical new way of thinking about some of life’s tiniest components .

Miller is among a small but growing group of scientists who believe we should no longer think of cells as passive robots that automatically follow a code of instructions, carrying out orders from our genome like mindless drones. Instead, they say, the roughly 37 trillion cells that make up our own bodies are conscious —and that life and consciousness began at the same time.

It’s a revolutionary idea, Miller tells Popular Mechanics , but assuming cells have a form of consciousness can give us a better understanding of complex processes. These include cellular communication and decision-making, and even the motivation behind an embryonic cell specializing into a specific organ. While it’s not widely accepted among scientists, this concept of “ existential consciousness ” will profoundly transform the way we approach cellular bioengineering problems like tissue regeneration, provide a different perspective on finding cures for diseases like cancer , and even help us survive on Mars, Miller says.

Now, in a May 2024 paper published in the peer-reviewed journal Progress in Biophysics and Molecular Biology, Miller and his fellow authors argue that random chance did not govern the concept of natural selection; that’s what the 1850s naturalist Charles Darwin, known for establishing the theory of evolution, thought. Instead, the authors contend that a form of cellular consciousness actually drove life’s evolution —and it’s the reason behind all of life’s existence. CONSCIOUSNESS, AT THE LEVEL OF THE CELL , cannot produce a human being’s own, complex thoughts, feelings, and sensations; a cell doesn’t have the capacity for abstract thought. But here’s how it does work, says Miller: Imagine a typical situation—daylight in a cell’s environment hits the cell’s external membrane and passes through it. The cell measures that light signal internally, forming a piece of information about the light. “Because it has to analyze it internally, that becomes an experience as the cell analyzes the light to support the state it prefers to be in [to fulfill its function],” Miller says. While that example is of a bacterial cell, all cells absorb various data from their surroundings, analyze them, and make decisions about the actions they should take, such as producing a hormone, or moving in a particular direction, perhaps toward the light.

From early in life’s history, cells of all kinds have combined their skills to further a common goal—to keep on living and reproducing. “Cells have formed colonies. It’s very much like a city that we humans might engineer. It has nutrient channels, an outside and an inside, a collective metabolism,” Miller says. For example, microbes collaborate with each other. They’re codependent, trading resources as well as competing. “In order to make this ecology flourish, each of these cells is taking intelligent action. They’re communicating with one another, and both individually and collectively deploying resources. That’s problem solving and decision making. That’s cognitive action, and it’s one element of consciousness,” he says.

It’s still a hard concept to swallow—that bacteria and other microorganisms are conscious on any level. To animals like us, consciousness is due to a complex nervous system.

.css-2l0eat{font-family:UnitedSans,UnitedSans-roboto,UnitedSans-local,Helvetica,Arial,Sans-serif;font-size:1.625rem;line-height:1.2;margin:0rem;padding:0.9rem 1rem 1rem;}@media(max-width: 48rem){.css-2l0eat{font-size:1.75rem;line-height:1;}}@media(min-width: 48rem){.css-2l0eat{font-size:1.875rem;line-height:1;}}@media(min-width: 64rem){.css-2l0eat{font-size:2.25rem;line-height:1;}}.css-2l0eat b,.css-2l0eat strong{font-family:inherit;font-weight:bold;}.css-2l0eat em,.css-2l0eat i{font-style:italic;font-family:inherit;} “Every aspect of the consciousness that I’m experiencing is a simultaneous aggregation of the consciousnesses of all of my body cells and all of those microbes working in tandem, coordinating so seamlessly that I feel like I’m one individual.”

However, Miller and his fellow authors see this higher, human form of consciousness as a natural property our cells create—together with the more than 10 trillion essential microbes that are a part of our bodies. “Every aspect of the consciousness that I’m experiencing is a simultaneous aggregation of the consciousnesses of all of my body cells and all of those microbes working in tandem, coordinating so seamlessly that I feel like I’m one individual,” he says.

Before exploring that idea further, it’s important to understand one thing: We are holobionts , because we consist of our own host cells and the ones we live with in symbiosis, or mutual cooperation. In particular, we live in symbiosis with a bacterial, viral, and fungal population of cells. In other words, our cells and our microbes mutually benefit one another.

The evolutionary science of the hologenome —that we co-evolved with our microbiome—says that evolution led those first cells to continue forming different kinds of habitats in order to survive and thrive; hence, the development of plants, animals, and fungi. “We’re a constellation of habitats,” says Miller, who spent decades studying the human microbiome and has written several books on the hologenome . He compares human bodies to a successful engineering project for ever more complex groupings of diverse cells living together and adapting to changing environments over millions of years. A form of cellular consciousness has been with us since life first emerged, 3.5 billion years ago. They were able to multiply into abundant varieties of bacteria, amoeba, and then more complex organisms because of their particular awareness. Today, your brain, microbiome and the cells of your gut work together as a community of cells to create your sense of consciousness.

“We are a rich, wonderful, delightful environment for cells,” he says. “So, we bear a resemblance to the first biofilm [microbial colony]. …We are one end result, along with every other creature that can be seen—we are a particular solution to a set of biological cellular problems.”

The authors of The Sentient Cell aren’t alone in hypothesizing that our microbes, the bacteria and viruses in us, have a great deal to do with our consciousness. Various studies show that our own cells communicate with our microbiome, and that our brain, gut, and microbiome are deeply entangled, forming a complex system. Besides being responsible for our health, these complex interactions contribute to our higher level consciousness, according to a 2020 paper in the peer-reviewed Inquiries Journal .

HOWEVER, NOT ALL SCIENTISTS who study the biology of life are convinced that cells are conscious. Cells respond to both chemical and physical signals, including pressure from surrounding cells. The cells of a developing embryo know, for example, when their number has grown to 400. At this exact point, the group begins to separate into three axes that determine the body’s final orientation: front and back, left and right, up and down. They know how to differentiate themselves into the tissues that will become your organs and other parts. Cells are the architects of the organism, cell biologist Alfonso Martínez Arias, Ph.D., tells Popular Mechanics .

His work shows that a person’s genome is a toolbox for the cell to use as it may. Yet we cannot presume that a cell’s behavior is due to consciousness, says Martínez Arias, who spent 40 years at the University of Cambridge researching how a fertilized egg can become an individual with billions of specialized cells.

While cells exhibit behaviors that you could call a sort of intelligence—responding to other cells and their environment—the crux of the problem is that it’s hard to define consciousness, he says. “With cells, there is some kind of computation going on, with an output that can be predicted. …I think increasingly, there is evidence that cells have capacities that are not encoded in the genome.” For instance, the ability to pick and choose from the toolbox of genes that give us our ultimate characteristics. Through experiments, researchers have been able to study cell responses to different chemical and physical stimuli, such as exposing them to a chemical compound that would cause the cells to produce a different compound. “So we are able to communicate with them, but we do it badly. …But I think we are learning their alphabet, we’re learning their language,” Martínez Arias says. He hopes that continuing such investigations will lead us someday to knowing what makes cells tick.

Conventional resistance to labeling cells as “conscious” comes from defining consciousness from a human point of view, Miller believes. We compare our own consciousness to the capacity of other animals, such as the mosquito or the lion. “And the more you look, the more you realize that our form of consciousness, with its own intelligence, is different from other animals, [so our view is skewed].” A cell’s consciousness is more elemental, a simpler form of cognition, he says.

Here’s a practical reason to treat cells as conscious, Miller says: Once we realize that cells are “creative and intelligent problem-solving materials,” we can treat them as partners in designing better biomedical therapies and solutions. By studying their motivations and decision-making, we’ll find more ways to manipulate cells, such as interrupting their processes. For example, cancer cells communicate with each other and with non-cancer cells in the body. We are finding promising cures for some cancers that break down the communication cancer cells use in their efforts to propagate and form tumors. This type of directed immunotherapy leaves patients’ own healthy cells undamaged, unlike chemotherapy, or radiation, which damages healthy cells too.

We’re already taking advantage of cell behavior to engineer microbes that eat plastic. Such creative solutions in the future won’t be possible if we treat cells as robots without preferences, Miller says. We’ll even understand how to explore space better. For example, the radiation levels on a journey to Mars are too high to survive. One of the solutions could be figuring out a way to strengthen our cells against dangerous radiation. Miller believes a study of how cells themselves could engineer an adaptation to radiation would help.

Before joining Popular Mechanics , Manasee Wagh worked as a newspaper reporter, a science journalist, a tech writer, and a computer engineer. She’s always looking for ways to combine the three greatest joys in her life: science, travel, and food.

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• June 17, 2024 | Great Ape Research Reveals Y Chromosome Is Evolving Faster Than the X
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Great Ape Research Reveals Y Chromosome Is Evolving Faster Than the X

By SciTechDaily June 17, 2024

Recent research has produced detailed genomes of sex chromosomes for six ape species, showing significant variability and evolution on the Y chromosome. This work aids in understanding reproductive genetics and could impact studies of human diseases linked to these chromosomes. Credit: SciTechDaily.com

New end-to-end X and Y chromosome sequences uncover enormous variation on the Y chromosome, informing human evolution and disease as well as conservation genetics of endangered apes.

A collaborative research team has generated complete reference genomes for the sex chromosomes of several great and lesser apes, revealing rapid evolutionary changes, particularly on the Y chromosome. These findings provide a basis for future studies on ape reproduction, fertility, and sex-specific genetic traits, enhancing understanding of primate evolution and related human diseases.

Ape Sex Chromosome Research

An international team from Penn State, the National Human Genome Research Institute, and the University of Washington has produced complete “end-to-end” reference genomes for the sex chromosomes of five great ape species and one lesser ape species. Their research reveals rapid evolutionary changes in the male-specific Y chromosome. These insights enhance our understanding of sex chromosome evolution and contribute to the knowledge of genetic diseases affecting both apes and humans.

The Importance of Y and X Chromosomes in Apes

“The Y chromosome is important for human fertility, and the X chromosome harbors genes critical for reproduction, cognition, and immunity,” said Kateryna Makova, Verne M. Willaman Chair of Life Sciences, professor of biology at Penn State and leader of the research team. “Our study opens doors for many future investigations of sex chromosomes, how they evolved and diseases associated with them. The living non-human great ape species we studied are all endangered. The availability of their complete sex chromosome sequences will facilitate studies of their sex-specific dispersal in the wild and of their genes important for reproduction and fertility.”

Newly generated, complete genomes for the sex chromosomes of six primate species — produced by an international collaboration led by researchers at Penn State and the National Human Genome Research Institute — reveal rapid evolution on the Y chromosome among apes. These results may inform conservation of these endangered species and shed light on sex-related genetic diseases in both humans and our closest living relatives. Credit: Design: Bob Harris; Photography: San Diego Zoo and Tulsa Zoo

Evolutionary Insights From Y Chromosome Variability

Such reference genomes act as a representative example that are useful for future studies of these species. The team found that, compared to the X chromosome, the Y chromosome varies greatly across ape species and harbors many species-specific sequences. However, it is still subject to purifying natural selection — an evolutionary force that protects its genetic information by removing harmful mutations.

The new study was recently published in the journal Nature .

Technological Advances in Genomic Sequencing

“Researchers sequenced the human genome in 2001, but it wasn’t actually complete,” Makova said. “The technology available at the time meant that certain gaps weren’t filled in until a renewed effort led by the Telomere-to-Telomere, or T2T, Consortium in 2022-23. We leveraged the experimental and computational methods developed by the Human T2T Consortium to determine the complete sequences for the sex chromosomes of our closest living relatives—great apes.”

Comparative Genomics of Great Apes

The team produced complete sex chromosome sequences for five species of great apes — chimpanzee, bonobo, gorilla, Bornean orangutan and Sumatran orangutan, which comprise most great ape species living today — as well as a lesser ape, siamang. They generated sequences for one individual of each species. The resulting reference genomes act as a map of genes and other chromosomal regions, which can help researchers sequence and assemble the genomes of other individuals of that species. Previous sex chromosome sequences for these species were incomplete or — for the Bornean orangutan and siamang — did not exist.

“The Y chromosome has been challenging to sequence because it contains many repetitive regions, and, because traditional short-read sequencing technology decodes sequences in short bursts, it is difficult to put the resulting segments in the correct order,” said Karol Pál, postdoctoral researcher at Penn State and a co-first author of the study. “T2T methods use long-read sequencing technologies that overcome this challenge. Combined with advances in computational analysis, on which we collaborated with Adam Phillippy’s group at the NHGRI, this allowed us to completely resolve repetitive regions that were previously difficult to sequence and assemble. By comparing the X and Y chromosomes to each other and among species, including to the previously generated human T2T sequences of the X and the Y, we learned many new things about their evolution.”

High Variability on the Y Chromosome

“Sex chromosomes started like any other chromosome pair, but the Y has been unique in accumulating many deletions, other mutations and repetitive elements because it does not exchange genetic information with other chromosomes over most of its length,” said Makova, who is also the director of the Center for Medical Genomics at Penn State.

As a result, across the six ape species, the research team found that the Y chromosome was much more variable than the X over a variety of characteristics, including size. Among the studied apes, the X chromosome ranges in size from 154 million letters of the ACTG alphabet — representing the nucleotides that make up DNA — in chimpanzee and human to 178 million letters in gorilla. In contrast, the Y chromosome ranges from 30 million DNA letters in siamang to 68 million letters in Sumatran orangutan.

The amount of DNA sequence shared between species was also more variable on the Y. For example, about 98% of the X chromosome aligns between human and chimpanzee, but only about a third of the Y aligns between them. The researchers found that this is in part because the Y chromosome is more likely to be rearranged or have portions of its genetic material duplicated.

Additionally, the percentage of the chromosome occupied by sequences that are repeated is highly variable on the Y. Whereas, depending on the species, 62% to 66% of the X chromosomes are occupied by repetitive elements, 71% to 85% of the Y chromosomes are occupied by them. These percentages are higher on both the X and the Y than in other chromosomes in the human genome.

Strategies for Y Chromosome Survival

“We found the ape Y to be shrinking, accumulating many mutations and repeats, and losing genes,” Makova said. “So why hasn’t the Y chromosome disappeared, as some previous hypotheses suggested? In collaboration with Sergei Kosakovsky Pond from Temple University and others, we found that the Y chromosome still has a number of genes evolving under purifying selection — a type of natural selection that keeps gene sequences intact. Many of these genes are important for spermatogenesis. This means that the Y chromosome is unlikely to disappear any time soon.”

The researchers found that many genes on the Y chromosome seem to use two strategies to survive. The first takes advantage of genetic redundancy — the presence of multiple copies of the same gene on a chromosome — so that intact copies of the gene can compensate for copies that might acquire mutations. The team quantified this genetic redundancy by completing the landscape of multi-copy gene families on ape sex chromosomes for the first time.

The second survival strategy takes advantage of palindromes, where the sequence of letters in the DNA alphabet is followed by the same, but inverted sequence, for example, ACTG-GTCA. When located within a palindrome, genes benefit from the palindrome’s ability to correct mutations.

“We found that the Y chromosome can exchange genetic information with itself between the repeated sequences of the two palindrome arms, which fold so that the inverted sequences align,” Pál said. “When two copies of the same gene are located within palindromes, and one copy is hit by a mutation, the mutation can be rescued by the genetic exchange with another copy. This can compensate for the Y’s lack of genetic information exchange with the other chromosomes.”

The research team obtained the complete sequences of palindromes on ape sex chromosomes also for the first time, as they were previously difficult to sequence and study. They found that palindromes are particularly abundant and long on the ape Y chromosome, yet they are usually only shared among closely related species.

Advances in Ape Genomic Research

In collaboration with Michael Schatz and his team at Johns Hopkins University, the researchers also studied the sex chromosomes of 129 individual gorillas and chimpanzees to better understand the genetic variation within each species and search for evidence of natural selection and other evolutionary forces acting on them.

“We obtained substantial new information from previously studied gorilla and chimpanzee individuals by aligning their sex chromosome sequencing reads to our new reference sequences,” said Zachary Szpiech, assistant professor of biology at Penn State and an author of the paper. “While increasing the sample size in the future will be very helpful to improve our ability to detect signatures of different evolutionary forces, this can be ethically and logistically challenging when working with endangered species, so it is critical that we can get the most out of the data we do have.”

The researchers explored a variety of factors that could explain variation on the Y chromosome within gorillas and within chimpanzees, and this analysis revealed additional signatures of purifying selection on the Y. This confirms the role of this type of natural selection on the Y, as was discovered in their previous analyses of genes.

Implications for Future Studies and Conservation Efforts

“The powerful combination of bioinformatic techniques and evolutionary analyses that we used allows us to better explain the evolutionary processes acting on sex chromosomes in our closest living relatives, great apes,” said Christian Huber, assistant professor of biology at Penn State and an author of the paper. “Additionally, the reference genomes we produced will be instrumental for future studies of primate evolution and human diseases.”

For more on this research, see Evolutionary Insights Revealed by First Complete Chromosome Sequences From Great Apes .

Reference: “The complete sequence and comparative analysis of ape sex chromosomes” by Kateryna D. Makova, Brandon D. Pickett, Robert S. Harris, Gabrielle A. Hartley, Monika Cechova, Karol Pal, Sergey Nurk, DongAhn Yoo, Qiuhui Li, Prajna Hebbar, Barbara C. McGrath, Francesca Antonacci, Margaux Aubel, Arjun Biddanda, Matthew Borchers, Erich Bornberg-Bauer, Gerard G. Bouffard, Shelise Y. Brooks, Lucia Carbone, Laura Carrel, Andrew Carroll, Pi-Chuan Chang, Chen-Shan Chin, Daniel E. Cook, Sarah J. C. Craig, Luciana de Gennaro, Mark Diekhans, Amalia Dutra, Gage H. Garcia, Patrick G. S. Grady, Richard E. Green, Diana Haddad, Pille Hallast, William T. Harvey, Glenn Hickey, David A. Hillis, Savannah J. Hoyt, Hyeonsoo Jeong, Kaivan Kamali, Sergei L. Kosakovsky Pond, Troy M. LaPolice, Charles Lee, Alexandra P. Lewis, Yong-Hwee E. Loh, Patrick Masterson, Kelly M. McGarvey, Rajiv C. McCoy, Paul Medvedev, Karen H. Miga, Katherine M. Munson, Evgenia Pak, Benedict Paten, Brendan J. Pinto, Tamara Potapova, Arang Rhie, Joana L. Rocha, Fedor Ryabov, Oliver A. Ryder, Samuel Sacco, Kishwar Shafin, Valery A. Shepelev, Viviane Slon, Steven J. Solar, Jessica M. Storer, Peter H. Sudmant, Sweetalana, Alex Sweeten, Michael G. Tassia, Françoise Thibaud-Nissen, Mario Ventura, Melissa A. Wilson, Alice C. Young, Huiqing Zeng, Xinru Zhang, Zachary A. Szpiech, Christian D. Huber, Jennifer L. Gerton, Soojin V. Yi, Michael C. Schatz, Ivan A. Alexandrov, Sergey Koren, Rachel J. O’Neill, Evan E. Eichler and Adam M. Phillippy, 29 May 2024, Nature . DOI: 10.1038/s41586-024-07473-2

In addition to Makova, Pál, Szpiech and Huber, the research team at Penn State includes Kaivan Kamali, computational scientist in the departments of biology and of biochemistry and molecular biology; Troy LaPolice, graduate student in bioinformatics and genomics; Paul Medvedev, professor of computer science and engineering and of biochemistry and molecular biology; Sweetalana, research assistant in the department of biology; Huiqing Zeng, research technologist in biology; Xinru Zhang, graduate student in bioinformatics and genomics; Robert Harris, assistant research professor of biology, now retired; Barbara McGrath, associate research professor of biology, now retired; and Sarah Craig, associate research professor of biology, currently a program officer at the National Institutes of Health . The co-authors also included Penn State alumni Monika Cechova, currently a postdoctoral fellow at the University of California Santa Cruz, and Melissa Wilson, currently an associate professor at Arizona State University.

In addition to Makova, the team was co-led by co-corresponding study authors Adam Phillippy, senior investigator at NHGRI, and Evan Eichler, professor of Genome Sciences at the University of Washington.

Funding from the National Institutes of Health supported this research.

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Evolution may be purposeful and it’s freaking scientists out.

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scientists are worried

“Where are all the genetic cures?” asks Denis Noble, a frustrated biophysicist, Royal Society fellow and pioneer of the field of systems biology. “They don’t exist. Where will they be? They won’t exist.” Since mapping the human genome in 2003, research priorities and funding shifted significantly towards genetics. The investment improved disease detection and management but failed to deliver on its promise of cures for our most common deadly diseases like heart disease, type 2 diabetes, Alzheimer’s and most cancers. Compounding the issue, a large-scale, 2023 study concluded that genetic risk scores perform poorly at predicting who’s going to develop common diseases. For Noble, the billions invested annually in genetic research represents less of a strategy and more of a scientific confusion—that we are our genes.

The scientific story of who we are is a reductionist, gene-centric model that forfeits natural phenomena like purpose due to its association with intelligent design and a transcendent, intelligent designer. Noble is neutral on religious matters. Yet he sees compelling evidence that purpose may be fundamental to life. He’s determined to debunk the current scientific paradigm and replace the elevated importance of genes with something much more controversial. His efforts have enraged many of his peers but gained support from the next generation of origins-of-life researchers working to topple the reign of gene-centrism. If successful, the shift could not only transform how we classify, study and treat disease, but what it means to be alive.

Emergent Heart Beats

One of the earliest biomedical computer programmers, Noble created the first model for a working human heart in 1960 on a vacuum tube computer. The project led to his discovery that heartbeats are emergent properties—new phenomena—arising from feedback loops, transforming our understanding of heart function and underpin treatments for heart conditions that we use today. His research on the heart’s pacemaker demonstrates a prioritization of the organism as a whole over its genes alone. “Several genes could individually be knocked out but the process continues,” says Noble. These genes are responsible for heart rhythm, yet other mechanisms can take over to get the job done.

In the 1960s, Noble served as the dissertation examiner for the then-unknown Richard Dawkins. Dawkins—a prominent figure in the New Atheism movement—would go on to author the 1976 classic The Selfish Gene that popularized the gene-centric theory of evolution. Gene-centrism says evolution acts on genes, not individual organisms. We are merely vessels for our genes that are driving evolution by Darwinian natural selection. Noble's analysis suggests that evolution acts on the organism as a whole, with the organism harnessing randomness and variation to create and heal itself—on purpose. In this re-evaluation, Noble believes that purpose, creativity, and innovation are fundamental to evolution. He argues that we experience these processes as drives, but they are not purely subjective. They also progress non-consciously in other parts of our body. These natural processes harness randomness and unpredictability—stochasticity—to survive, make decisions, and thrive. “Stochasticity is the center of creativity in organisms,” says Noble.

Evolution on Purpose

Noble’s formal training is in cellular electrophysiology, the study of the differences in electrical charges inside and outside of a cell membrane. He suspects that crevices of ancient rocks served as cradles for emergent self-sustaining systems. Eventually, membranes evolved from lipid-coated bubbles, replacing the fissures in rocks as containers for these emergent systems. This gave rise to the first living entity—a single-celled organism. According to Noble, the constraints of a cell’s membrane and the restriction of freedom of molecules inside a cell, made purpose both possible and necessary. This development required a sort of intention or cognition within emergent networks of molecules to create and sustain biological functions.

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Noble sees evidence of purposive and intentional evolution in our immune response to viruses. Detection of the invader triggers a flurry of rapid mutations in the genes of B cells, creating a legion of gene variants. These variants are antibodies, the most effective of which are deployed to combat the virus. In a defensive assault, the immune system self-modifies its own DNA. “It changes the genome. Not supposed to be possible,” says Noble. “Happens all the time.”

The conventional view is that this is still random natural selection—cranked up to warp speed inside the body during the lifetime of an individual organism. Noble agrees, but adds the observation that the organism’s immune system initiates and orchestrates the ramped up process, harnessing natural selection to fight off the invader. For Noble, this routine procedure offers clear evidence of the organism actively participating in its own evolution—it’s doing natural selection. This is an alternative theory of evolution where cognition is fundamental. In this theory, the smallest unit of life—cells—have some version of intelligence and intent that allows them to detect and respond to their environment. Noble clocks the immune response as a goal-directed pattern of behavior at the cellular level that scales to every level of organization within a living system. He believes we’re working ourselves into a sweat to exclude something so essential to evolution and to life as purpose and intention.

The Future of Evolution

Noble is part of The Third Way, a movement in evolutionary biology that views natural selection as part of a holistic, organism-centered process. He co-authored Evolution “on Purpose," published by MIT Press in 2023, which argues that organisms evolve with intention.

Recent research calls into question whether genetic mutations are even entirely random. A 2022 study in Nature shows a mutation bias supporting the organism as a whole. Noble doesn’t understand why studies like these aren’t making bigger waves. “Do you, you people working in gene-centric biology, do you realize what has already been published?” asks an incredulous Noble.

This is one of his central criticisms of Richard Dawkins, whom Noble dubs the primary exponent of gene-centrism. Dawkins is one of the world’s foremost science communicators. Noble considers Dawkins an exceptional writer who simply hasn’t kept up with the science. When asked for comment, Dawkins responded, “I have a whole chapter dealing with Denis Noble in my next book, The Genetic Book of the Dead . It will be available in September.”

Where Evolution Went Wrong

Noble attributes our legacy of missteps to rigid assumptions put in place over a century ago to stand in for a lack of evidence. Darwin’s namesake theory of evolution by natural selection was first published in 1859. This slow process alters instructions to build an organism only through genetic mechanisms like random mutations and recombination that get passed down to offspring.

Near the end of his life, Darwin was corresponding with physiologist George Romanes, exploring additional mechanisms of inheritance and the role of physiology. Despite Darwin’s broadening views, his theory was scaled back posthumously. Following Darwin’s death in 1882, biologist and ‘Neo-Darwinist’ August Weismann promulgated the idea of a one-way barrier cordoning off reproductive cells from the rest of the body. This barrier required that reproductive cells were the sole vehicles for inheritance. Neo-Darwinists would go on to revive a theory of genes and genetic recombination. Mendelian genetics with Darwin’s natural selection were synthesized. The reproductive cells became the housing for genes which ascended to the centerpiece for evolution.

In 1894 at age 46, Romanes died of a cerebral hemorrhage. And so died the lone voice advocating for Darwin’s ultimate views—views of evolution which emphasized more complexity and physiology. Noble suspects if Romanes had survived, we may have avoided a gene-centric paradigm paralysis. Instead, Noble feels “our genetic hope is more about faith than facts.”

Mortality And A New Biology

Noble is urgently reviving and expanding on Darwin and Romanes. Last month, a special edition of The Journal of Physiology, co-edited by Noble and Michael Joyner of the Mayo Clinic, featured 21 articles challenging current evolutionary theory and advocating for the inclusion of phenomena like agency and cognition.

These articles corroborate the general theme that Genes Are Not The Blueprint For Life , the title of Noble’s review in the journal Nature, heralding science writer Philip Ball’s primer How Life Works: A User’s Guide to The New Biology. Ball, a former editor of Nature, admonishes the life sciences for ignoring obvious natural properties of living systems like agency and purpose because of “quasi-mystical” associations with intelligent design. In the book, Ball illustrates the resistance to letting go of the “tidy tale” of gene-centrism and the idea that genes control health more than “‘a bit’ and ‘somewhat’.” Like Noble, Ball is advocating for a new biology.

Noble’s urgency is more than academic. “This is critical to the future of health care,” says Noble, who feels the public is paying the ultimate price for gene-centrism. “I face the same problem as many other people face,” says Noble. “Families having to deal with serious illness, with social care that costs more than you can ever afford. I've been through all of that. I know what it does to families.” He considers it a foregone conclusion that aging populations will strain health systems to the point of rupture if we continue with gene-centrism.

The Critics

Noble’s critics worry that entertaining religion-adjacent views subverts established science and the entire scientific project. But Noble’s research doesn’t challenge the scientific method. It challenges a scientific epoch marked by a purely mechanistic view of nature that coincided with the Industrial Revolution and age of mechanization. Noble appreciates concerns raised by skeptics, yet refuses to exclude natural phenomena from scientific inquiry.

Noble’s critics also accuse him of exaggerating the importance of physiology, while Noble insists physiology has been unjustly sidelined since Darwin. “Physiology now has to come to the rescue of evolutionary biology,” says Noble.

Another objection is that Noble is contesting a theory of evolution that has since been revised to address new evidence. For Noble, this is exactly his point. New evidence doesn’t merely refine the theory, it undermines it.

Biology’s existential crisis reached a flashpoint in 2016, when Noble and a group of scientists and philosophers organized a conference on New Trends in Evolutionary Biology with the Royal Society of London. Royal Society members petitioned—unsuccessfully—to kill it. The protest letter (Royal Society member Richard Dawkins’ signature was noticeably absent) read “...we wish to express our concern that this meeting will severely damage the reputation of the Society among the worldwide community of evolutionary biologists (it has already attracted adverse comments among colleagues in the USA).”

They never name their U.S. colleagues, although American biologist and prominent anti-creationist, Jerry Coyne uses words like "stupid," "rotten" and “blundering tyro” in his public condemnation of Noble. Canadian biologist Laurence A. Moran echoes Coyne’s outrage adding, “It's difficult not to be very angry at people like Denis Noble.” Moran writes that if science was working properly, Noble would “fade into the woodwork of the Senior Common Room at some college in Oxford.” It’s true Noble didn’t raise serious objections to evolutionary theory until after he retired as Chair of Cardiovascular Physiology at the University of Oxford in 2004. He says “coming out” would have invariably damaged the reputation and careers of the research team in his lab.

The Next GeneRation

“We need to shame them. I'm sorry, but we do,” says bioengineer and origins-of-life scientist Joana Xavier about Noble’s caustic critics. Xavier, a next-generation evolutionary theorist, resents “bullying” from prominent scientists that shuts down young biologists and stymies scientific progress. She and her peers have new tools and fresh perspectives, yet Xavier says their academic careers are jeopardized by demeaning attacks.

Xavier’s research made headlines for her discovery of emergent, cooperative networks of molecules that mutually catalyze each other's formation in ancient bacteria. These systems were first theorized by complexity scientist, Stuart Kauffman, as a candidate for the origins-of-life story that challenges gene-centrism. Xavier studied under Noble and Kauffman before launching the Origin of Life Early-Career Network (OoLEN) with over 200 young, interdisciplinary researchers from around the world. This group co-authored an inaugural scientific paper The Future of Origin of Life Research: Bridging Decades-Old Divisions.

Xavier has identified another indication of intention at the cellular level of emergent systems: cooperation . She doesn’t understand why it’s acceptable to think of evolution as competitive but evidence of cooperation is considered taboo. “I think to solve life's origins, we'll need to look much more at cooperation. And emergence really brings cooperation into the scene, whether you want it or not,” says Xavier, who also sees creativity as fundamental to life. “It's so obvious, you either accept that it is true that life is creative or you don't.”

Xavier says her field is at an inflection point with gene-centrism holding back progress in health and medicine. “I think we’re completely stuck,” says Xavier. She’s actively pushing in a new direction even if she has to leave academia for the private sector to do it. “The gene-centric paradigm,” says Xavier, “That has to go. It's urgent.”

These days, Noble is surrounded by young researchers eager to reopen the case of evolution. “I have young people helping me with all of this because, believe me, I can't do all of this on my own,” says Noble. Creativity, purpose and organism-centered evolution are still only postulates that need rigorous testing. Noble is eager to explore both his theory and others. With theories of who we are, how we heal, and how we came to exist, Noble stresses “we should have more than one horse in the race.”

Watch the interviews with Noble and others that informed this article here:

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Using a combination of machine learning and playback experiments in the field, we find that African savannah elephants address members of their family with individually specific, name-like calls. These ‘names’ are probably not imitative of the receiver’s calls, which is similar to human naming but unlike known phenomena in other animals.

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King, S. L. & Janik, V. M. Bottlenose dolphins can use learned vocal labels to address each other. Proc. Natl Acad. Sci. USA 110 , 13216–13221 (2013). An article that shows that bottlenose dolphins address one another by copying the signature whistle of the addressee.

Article   CAS   PubMed   PubMed Central   Google Scholar  

Balsby, T. J. S., Momberg, J. V. & Dabelsteen, T. Vocal imitation in parrots allows addressing of specific individuals in a dynamic communication network. PLoS ONE 7 , e49747 (2012). A paper revealing that orange-fronted conures (a New World parrot) respond more to contact calls that imitate their own calls.

Dingemanse, M., Blasi, D. E., Lupyan, G., Christiansen, M. H. & Monaghan, P. Arbitrariness, iconicity, and systematicity in language. Trends Cogn. Sci. 19 , 603–615 (2015). A review of the extent to which the structure of human words is inherently connected to their meaning.

Article   PubMed   Google Scholar  

Poole, J. H., Tyack, P. L., Stoeger-Horwath, A. S. & Watwood, S. Elephants are capable of vocal learning. Nature 434 , 455–456 (2005). This paper provides evidence that African elephants are capable of vocal mimicry.

Article   CAS   PubMed   Google Scholar  

Wittemyer, G., Douglas-Hamilton, I. & Getz, W. M. The socioecology of elephants: analysis of the processes creating multitiered social structures. Anim. Behav. 69 , 1357–1371 (2005). This article reveals that female African savannah elephants have a hierarchically tiered, fission–fusion society.

Article   Google Scholar  

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This is a summary of: Pardo, M. A. et al. African elephants address one another with individually specific name-like calls. Nat. Ecol. Evol . https://doi.org/10.1038/s41559-024-02420-w (2024).

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African savannah elephants call one another by ‘name’. Nat Ecol Evol (2024). https://doi.org/10.1038/s41559-024-02430-8

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Published : 10 June 2024

DOI : https://doi.org/10.1038/s41559-024-02430-8

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