Early Humans

The Juicy History of Humans Eating Meat

The mouth-watering smokiness of a rack of pork ribs. But why do we eat so much more meat than our primate cousins and why are we wired to more

Why Did the Clovis People Mysteriously Vanish?

Ancient people of North America’s Clovis culture migrated to South America roughly 11,000 years ago, then mysteriously vanished, researchers have discovered. In a new study, researchers analyzed DNA from 49 people living over a span of 10,000 years in Belize, Brazil, the Central more

Early Americans Buried Their Dogs Like Family

We lived alongside mammoths, had not yet discovered bronze or writing and spent our lives moving constantly from place to place. But even 10,000 years ago, human beings loved their pet dogs. This fact is borne out in an ancient gravesite in Illinois, where a trio of dogs were more

Stone Age

The Stone Age marks a period of prehistory in which humans used primitive stone tools. Lasting roughly 2.5 million years, the Stone Age ended around 5,000 years ago when humans in the Near East began working with metal and making tools and weapons from bronze. During the Stone more

Neolithic Revolution

The Neolithic Revolution, also called the Agricultural Revolution, marked the transition in human history from small, nomadic bands of hunter-gatherers to larger, agricultural settlements and early civilization. The Neolithic Revolution started around 10,000 B.C. in the Fertile more


Hunter-gatherers were prehistoric nomadic groups that harnessed the use of fire, developed intricate knowledge of plant life and refined technology for hunting and domestic purposes as they spread from Africa to Asia, Europe and beyond. From African hominins of 2 million years more

Going Paleo: What Prehistoric Man Actually Ate

Newly popular in health circles, the Paleo diet was created back in the 1970s by gastroenterologist Walter Voegtlin. He was the first to suggest that eating like our Paleolithic ancestors could make modern humans healthier. A return to the diet of our forebears, according to more

Europe’s Oldest Natural Mummy Has Living Relatives

The study, published in the journal Science, linked Ötzi with his living relatives by tracing a rare genetic mutation on the Y-chromosome. The mutation, known as G-L91, is passed down along the male line, and scientists at Austria’s Institute for Forensic Medicine have been using more

Human Ancestors Tamed Fire Earlier Than Thought

Fire control changed the course of human evolution, allowing our ancestors to stay warm, cook food, ward off predators and venture into harsh climates. It also had important social and behavioral implications, encouraging groups of people to gather together and stay up late. more

Prehistoric Children Finger-Painted on Cave Walls

[slideshow exclude=”4153″]Located in the Dordogne region of France, the massive Rouffignac cave complex has captivated tourists and scholars with its vivid drawings of mammoths, rhinoceroses and horses for centuries. In 1956, a decade after its deep caverns harbored Resistance more

Scopes Monkey Trial begins

In Dayton, Tennessee, the so-called Scopes Monkey Trial begins with John Thomas Scopes, a young high school science teacher, accused of teaching evolution in violation of a Tennessee state law. The law, which had been passed in March, made it a misdemeanor punishable by fine to more

Lascaux cave paintings discovered

Near Montignac, France, a collection of prehistoric cave paintings are discovered by four teenagers who stumbled upon the ancient artwork after following their dog down a narrow entrance into a cavern. The 15,000- to 17,000-year-old paintings, consisting mostly of animal more

Ishi discovered in California

Ishi, who was described as the last surviving member of the Native Amercain Yahi tribe, is discovered in California on August 29, 1911. By the first decade of the 20th century, Euro-Americans had so overwhelmed the North American continent that scarcely any Native Americans more

The “Trial of the Century” draws national attention

Schoolteacher John T. Scopes is convicted of violating Tennessee’s law against teaching evolution in public schools. The case debated in the so-called “Trial of the Century” was never really in doubt; the jury only conferred for a few moments in the hallway before returning to more

Early Human Evolution and Culture

The Early Human Evolution teaching resources support students in meeting the following middle school NGSS Performance Expectations.

Life Science

MS-LS1 From Molecules to Organisms: Structures and Processes

  • MS-LS1-4 Use argument based on empirical evidence and scientific reasoning to support an explanation for how characteristic animal behaviors and specialized plant structures affect the probability of successful reproduction of animals and plants respectively.

MS-LS4 Biological Evolution: Unity and Diversity

  • MS-LS4-1 Analyze and interpret data for patterns in the fossil record that document the existence, diversity, extinction, and change of life forms throughout the history of life on Earth under the assumption that natural laws operate today as in the past.
  • MS-LS4-2 Apply scientific ideas to construct an explanation for the anatomical similarities and differences among modern organisms and between modern and fossil organisms to infer evolutionary relationships.

Anne and Bernard Spitzer Hall of Human Origins

The Anne and Bernard Spitzer Hall of Human Origins pairs fossils with DNA research to present the remarkable history of human evolution. The hall covers millions of years of human history, from early ancestors who lived more than six million years ago to modern Homo sapiens, who evolved 200,000 to 150,000 years ago.

This innovative exhibition combines discoveries in the fossil record with the latest genomic science to explore the most profound mysteries of humankind: who we are, where we came from, and what is in store for the future of our species. The hall explores human biology and anatomy, traces the path of human evolution, and examines the origins of human creativity.

Featuring four life-sized tableaux of Homo ergaster, Homo erectus, Neanderthals, and Cro-Magnons, the Spitzer Hall of Human Origins shows each species in its habitat, demonstrating the behaviors and capabilities that scientists think it had. Also displayed are a variety of important fossil casts, including the 1.7-million-year-old “Turkana Boy.” The hall also features examples of what are thought to be some of humans’ earliest forms of artistic expression, including an original limestone engraving of a horse carved about 25,000 years ago in southwestern France.

Learn how you are like—and different from—a Neanderthal and a chimpanzee.

Peace or War? How Early Humans Behaved

Depending on which journals you've picked up in recent months, early humans were either peace-loving softies or war-mongering buffoons.

Which theory is to be believed?

A little bit of both, says one archaeologist, who warns against making generalizations when it comes to our long and varied prehistory.

The newest claim concerns Australopithecus afarensis, who lived approximately five million years ago and is one of the first hominids that can be linked directly to our lineage with some certainty. Hardly an expert at tearing other animals limb from limb, scientists say the small and furry creature likely spent most of its time avoiding becoming the lunch of those saber-toothed mammals you see in natural history museums today.

That's a far cry from the spear-wielding image most of the public has of our earliest ancestors, Robert Sussman of Washington University told an audience at the annual meeting of the American Association for the Advancement of Science last month.

Other research appearing in current scientific journals, however, paints a different picture of early man.

Groups of humans likely engaged in occasional violent encounters in order to increase their territory, argues Raymond C. Kelly of the University of Michigan in a recent edition of the Proceedings of the National Academy of Sciences. According to Kelly, this may have continued up until about a million years ago, when distance weapons like the spear were invented and increased the risks of attacking other groups.

How can scientists see things so differently?


Human evolution just isn't that simple, says Michael Bisson, professor of anthropology at McGill University in Montreal, Canada. People tend to make generalizations about our early ancestors, even though they lived for a period of several million years and include many entirely different species of hominids.

As for the peaceful nature of Australopithecus afarensis, Bisson wholeheartedly agrees with Sussman.

"Afarensis was small and completely non-technological. No one has ever argued that they were predatory. They are bipedal, ground-eating apes," Bisson said in an interview.

Interpretations get trickier, however, as time moves forward and hominids become more prevalent and diverse. When humans began to eat meat and use weapons, around two million years ago, some inter-group killings were almost certainly going on in the cases where individuals encroached on each other's territory.

Still, at this point hominids are mostly timid scavengers, according to Bisson, not mammoth-hunters.

"The interesting thing about early hominids and meat-eating is that all of the evidence we have for it is little animals that might have been caught and dismembered by hand and big animals that were scavenged," he said. "It fades in very slowly. After two million [years ago], there's about a half-million-year transition before you get to hunting of some kind."

Spear or tooth?

It's around this time where mistakes can be made in the fossil record, experts say. With humans beginning to hunt animals, weapons in hand, it's easier to assume they are also killing each other. Puncture wounds in a skull from an animal bite can be mistaken as injuries from a spear attack, for example.

The fossil record is not always an easy thing to read, Bisson explained.

"Cause of death is almost impossible to determine on all of these (fossils)," he said. "They have almost all been subject to scavenging. Since there's no deliberate burial at that time, the bodies end up part of the food chain, so we simply can't say what happened."

A lot can depend on how archaeological remains are interpreted. Sussman calls this the "5 o'clock news" version of history and science, one that applies to today's humans as easily as those of several million years ago.

"Human groups are much more likely to live in peace than in war," he explained. "What we usually find is that what is reported or emphasized is any violent encounter that takes place. Thus, instead of using the actual statistics, we emphasize the rare events."

Context of war

Bisson agrees that the archaeological remains must be put in context depending on who makes the find, even. He pointed to the discovery of some Australopithecus remains in the 1920s, in what is now Botswana. Along with a skull, the material found included tools made from the bones of gazelles, antelopes and wild boar. The archaeologist working there mistakenly interpreted them as a cache of weapons, while later testing would show the points were used simply for digging in termite holes.

"A lot of this stuff was written between the First and Second World War," he reasoned. "It was very easy to see warfare and violence as inherent in the human condition during a period when humanity was literally trying to exterminate itself."

Mainstream media can also have a lot to do with what the public believes as fact.

"No archaeologist in the last 40 years has bought the &lsquoKiller Ape' interpretation, but it did get ingrained in popular culture in the intro sequence to the famous Stanley Kubrick film ["2001: A Space Odyssey"]," Bisson said. In the movie, ape-like humans are shown having the eureka moment that bones can be used as weapons, thus evolving to become hunters and killers. "It's a fairly literal dramatization of the hypothesis, complete with leg bones used as clubs."

Even if early humans were mostly cooperative with each other during the Paleolithic era&mdasha period lasting about two million years&mdashthere is plenty of evidence to suggest that (like today), some people were just plain nasty. Cannibalism was clearly practiced in some areas, according to Bisson.

"We know that there is at least one case of Homo erectus with extensive cuts on the cranium indicating that the person was essentially scalped and the eyes gouged out," he said.

Early Human Essay for Children | Early Man Lifestyle | History

Man has developed from prehistoric ages from an ape like creature to what he is now. From fours he started walking on twos. From stooping on the ground he started to stand up on his legs. He learnt to walk run hunt and cook.

Man’s evolution came about in certain phases. It wasn’t done in a jiffy. But it came about in a very slow and gradual phase.

Before, man used to live on trees like apes. They had a huge head and a smaller brain. His senses weren’t that developed that time. His only means of survive was to eat the wild berries and fruits that grew on trees. He was a prey that time and not a predator, since he did not know any hunting skills. He was preyed on like other monkeys and apes. His body was full of hair and he had a tail also.

As time passed man came down from the trees to the land. He started residing in caves and niches in mountains. The hair quantity in his body reduced.

Then man developed tools. This brought a major change in his life. He learnt the art of hunting. He learnt how to make sharp object by rubbing two objects with each other. With tools now he could build temporary sheds and hunt animals at close proximity.

Another change that came with tools was that he started walking on twos instead of all fours. Yes! Man started using his lower limbs. But his walk wasn’t this upright and straight as it is now. It was more like how gorillas look when they walk on their feet slightly humped in front and the movement is from side to side.

While rubbing two stones to sharpen them man made another accidental discovery that is fire. Till then fire was a matter of mystery, something fearful, and something unknown. Something, that cannot be under control. It was an act of nature. But when man learnt this new trick he could produce fire at his will by rubbing two stones or two twigs together. He became the master of fire.

The size of his brain increased considerably. He stood more upright. With fire at control there came many advantages. He could now have cooked food (before man used to devour raw flesh) hence it enhanced his taste buds. He can now light up dark caves and stay up late in the night. Also now they have this instrument to protect themselves from wild animals. They can also keep themselves warm in winters. From a herbivore he became an omnivore.

By this time he had learnt to tame animals. He started taming animals of domestic behavior. Man started living in groups. From a nomadic nature he started having a family. From a collection of different families it soon turned into a prehistoric village.

Man shifted from the caves to the open land. He built himself huts. Separate huts for separate families. Man learnt that the soil near the river is most fertile and there is also an easy availability of water. Villages started coming up along the banks of the water sources.

Man started producing food instead of just eating the wild fruits. The very first grains to be cultivated are still unknown because at that time trees also hadn’t undergone much evolution and there were a lot more different species of trees. So the main diet of man comprised of wild fruits, berries, meat, milk from the animals he domesticated and the grains that he grew.

He started practicing shifting agriculture that is suppose they settled in an area and cleared the forest cover there and started their agriculture there. But after some years the soil will lose its fertility, then again the people will shift to a new area, make a new clearing and start cultivating again, and leave the earlier patch to regenerate itself.

Man now became more human like. He brain size increased. His face shrinked. His back became straighter. And he could now stand upright on his hind limbs. He could walk, run, and jump on his legs without any hindrance. Also he lost the use of his tail, since he didn’t need to hang from trees anymore. Hence, his tail started shrinking in size. And finally, it will be lost like ours in near future.

The third breakthrough came with the discovery of wheels. Man saw wooden logs of trees to roll down easily from a hill top. This gave him the idea of making wheels. He tied his domesticated animals to the wheels and used them to pull the wheels. This gave him the basic idea of making a cart. Early carts were very different from us though.

Nothing much is known about the language of early man at those times. Scientists say they didn’t have a proper context or verbal sentences. Instead they had calls like animals. He used to communicate or call each other through specific set of music, shrieks, cries or calls. They had separate calls for expressing joy , sorrow or giving signals for any danger lurking nearby.

Man started using different materials for building his home- like straw, wood, mud, bamboo and wood. With the advent of fire and wood man made another discovery that changed the pace of time. He discovered metals. He discovered ores from which metals can be formed. The very first metal to be discovered was copper.

Man can now store food. Before he used to store milk in earthen pots or skins of animals hence the food got easily wasted. But with copper utensils now he can store food easily for days. Food production became super functional. Man started producing food more than he needed. This gave him the idea of trade. He traded his grains for cattle or new weapons and utensils.

Such is the journey of man. This by and by gave rise to huge and renowned civilizations which shaped our future-like the Mayans, the Egyptians, the Greeks, the Romans, the Indus valley and many more. What we are now is because of them

For men may come, and men may go, but I go on forever” -the river

The Human Family’s Earliest Ancestors

Tim White is standing with a group of restless men atop a ridge in the Afar desert of Ethiopia. A few of them are pacing back and forth, straining to see if they can spot fragments of beige bone in the reddish-brown rubble below, as eager to start their search as children at an Easter egg hunt. At the bottom of the hill is a 25-foot-long cairn of black rocks erected in the style of an Afar grave, so large it looks like a monument to a fallen hero. And in a way it is. White and his colleagues assembled it to mark the place where they first found traces, in 1994, of “Ardi,” a female who lived 4.4 million years ago. Her skeleton has been described as one of the most important discoveries of the past century, and she is changing basic ideas about how our earliest ancestors looked and moved.

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More than 14 years later, White, a wiry 59-year-old paleoanthropologist from the University of California at Berkeley, is here again, on an annual pilgrimage to see if seasonal rains have exposed any new bits of Ardi’s bones or teeth. He often fires up the fossil hunters who work with him by chanting, “Hominid, hominid, hominid! Go! Go! Go!” But he can’t let them go yet. Only a week earlier, an Alisera tribesman had threatened to kill White and two of his Ethiopian colleagues if they returned to these fossil beds near the remote village of Aramis, home of a clan of Alisera nomads. The threat is probably just a bluff, but White doesn’t mess with the Alisera, who are renowned for being territorial and settling disputes with AK-47s. As a precaution, the scientists travel with six Afar regional police officers armed with their own AK-47s.

Arranging this meeting with tribal leaders to negotiate access to the fossil beds has already cost the researchers two precious days out of their five-week field season. “The best- laid plans change every day,” says White, who has also had to deal with poisonous snakes, scorpions, malarial mosquitoes, lions, hyenas, flash floods, dust tornadoes, warring tribesmen and contaminated food and water. “Nothing in the field comes easy.”

As we wait for the Alisera to arrive, White explains that the team returns to this hostile spot year after year because it’s the only place in the world to yield fossils that span such a long stretch of human evolution, some six million years. In addition to Ardi, a possible direct ancestor, it is possible here to find hominid fossils from as recently as 160,000 years ago—an early Homo sapiens like us—all the way back to Ardipithecus kadabba, one of the earliest known hominids, who lived almost six million years ago. At last count, the Middle Awash project, which takes its name from this patch of the Afar desert and includes 70 scientists from 18 nations, has found 300 specimens from seven different hominid species that lived here one after the other.

Ardi, short for Ardipithecus ramidus, is now the region’s best-known fossil, having made news worldwide this past fall when White and others published a series of papers detailing her skeleton and ancient environment. She is not the oldest member of the extended human family, but she is by far the most complete of the early hominids most of her skull and teeth as well as extremely rare bones of her pelvis, hands, arms, legs and feet have so far been found.

With sunlight beginning to bleach out the gray-and-beige terrain, we see a cloud of dust on the horizon. Soon two new Toyota Land Cruisers pull up on the promontory, and a half-dozen Alisera men jump out wearing Kufi caps and cotton sarongs, a few cinched up with belts that also hold long, curved daggers. Most of these clan “elders” appear to be younger than 40—few Alisera men seem to survive to old age.

After customary greetings and handshaking, White gets down on his hands and knees with a few fossil hunters to show the tribesmen how the researchers crawl on the ground, shoulder to shoulder, to look for fossils. With Ethiopian paleoanthropologist and project co-leader Berhane Asfaw translating to Amharic and another person translating from Amharic to Afariña, White explains that these stones and bones reveal the ancient history of humankind. The Alisera smile wanly, apparently amused that anyone would want to grovel on the ground for a living. They grant permission to search for fossils—for now. But they add one caveat. Someday, they say, the researchers must teach them how to get history from the ground.

The quest for fossils of human ancestors began in earnest after Charles Darwin proposed in 1871, in his book The Descent of Man and Selection in Relation to Sex, that humans probably arose in Africa. He didn’t base his claim on hard evidence the only hominid fossils then known were Neanderthals, who had lived in Europe less than 100,000 years ago. Darwin suggested that our “early progenitors” lived on the African continent because its tropical climate was hospitable to apes, and because anatomical studies of modern primates had convinced him that humans were more “allied” with African apes (chimpanzees and gorillas) than Asian apes (orangutans and gibbons). Others disagreed, arguing that Asian apes were closer to modern humans.

As it happened, the first truly ancient remains of a hominid—a fossilized skullcap and teeth more than half a million years old—were found in Asia, on the island of Java, in 1891. “Java man,” as the creature was called, was later classified as a member of Homo erectus, a species that arose 1.8 million years ago and may have been one of our direct ancestors.

So began a century of discovery notable for spectacular finds, in which the timeline of human prehistory began to take shape and the debate continued over whether Asia or Africa was the human birthplace.

In 1924, the Australian anatomist Raymond Dart, looking through a crate of fossils from a limestone quarry in South Africa, discovered a small skull. The first early hominid from Africa, the Taung child, as it was known, was a juvenile member of Australopithecus africanus, a species that lived one million to two million years ago, though at the time skeptical scientists said the chimpanzee-size braincase was too small for a hominid.

In 1959, archaeologist Louis Leakey and his wife Mary, working in Olduvai Gorge in Tanzania, discovered a bit of hominid jawbone that would later become known as Paranthropus boisei. The 1.75-million-year-old fossil was the first of many hominids the Leakeys, their son Richard and their associates would find in East Africa, strengthening the case that hominids indeed originated in Africa. Their work inspired American and European researchers to sweep through the Great Rift Valley, a geologic fault that runs through Kenya, Tanzania and Ethiopia and exposes rock layers that are millions of years old.

In 1974, paleoanthropologists Donald Johanson and Tom Gray, digging in Hadar, Ethiopia, found the partial skeleton of the earliest known hominid at the time—a female they called Lucy, after the Beatles’ song “Lucy in the Sky with Diamonds,” which was playing in camp as they celebrated. At 3.2 million years old, Lucy was remarkably primitive, with a brain and body about the size of a chimpanzee’s. But her ankle, knee and pelvis showed that she walked upright like us.

This meant Lucy was a hominid—only humans and our close relatives in the human family habitually walk upright on the ground. A member of the species Australopithecus afarensis, which lived from 3.9 million to 2.9 million years ago, Lucy helped answer some key questions. She confirmed that upright walking evolved long before hominids began using stone tools—about 2.6 million years ago—and before their brains began to expand dramatically. But her upright posture and gait raised new questions. How long had it taken to evolve the anatomy to balance on two feet? What prompted some ancient ape to stand up and begin walking down the path toward humanness? And what kind of ape was it?

Lucy, of course, couldn’t answer those questions. But what came before her? For 20 years after her discovery, it was as if the earliest chapter of the human story were missing.

One of the first teams to search for lucy’s ancestor was the Middle Awash project, which formed in 1981 when White and Asfaw joined Berkeley archaeologist J. Desmond Clark to search for fossils and stone tools in Ethiopia. They got off to a promising start—finding 3.9-million-year-old fragments of a skull and a slightly younger thighbone—but they were unable to return to the Middle Awash until 1990, because Ethiopian officials imposed a moratorium on searching for fossils while they rewrote their antiquities laws. Finally, in 1992, White’s graduate student, Gen Suwa, saw a glint in the desert near Aramis. It was the root of a tooth, a molar, and its size and shape indicated that it belonged to a hominid. Suwa and other members of the Middle Awash project soon collected other fossils, including a child’s lower jaw with a milk molar still attached. State-of-the-art dating methods indicated that they were 4.4 million years old.

The team proposed in the journal Nature in 1994 that the fossils—now known as Ardipithecus ramidus—represented the “long-sought potential root species for the Hominidae,” meaning that the fossils belonged to a new species of hominid that could have given rise to all later hominids. The idea that it was a member of the human family was based primarily on its teeth—in particular, the absence of large, dagger-like canines sharpened by the lower teeth. Living and extinct apes have such teeth, while hominids don’t. But the gold standard for being a hominid was upright walking. So was A. ramidus really a hominid or an extinct ape?

White joked at the time that he would be delighted with more fossils—in particular, a skull and thighbone. It was as if he had placed an order. Within two months, another graduate student of White’s, Ethiopian paleoanthropologist Yohannes Haile-Selassie, spotted two pieces of a bone from the palm of a hand—their first sign of Ardi. The team members eventually found 125 pieces of Ardi’s skeleton. She had been a muscular female who stood almost four feet tall but could have weighed as much as 110 pounds, with a body and brain roughly the same size as a chimpanzee’s. As they got a good look at Ardi’s body plan, they soon realized that they were looking at an entirely new type of hominid.

It was the find of a lifetime. But they were daunted by Ardi’s condition. Her bones were so brittle that they crumbled when touched. White called them “road kill.”

The researchers spent three field seasons digging out entire blocks of sedimentary rock surrounding the fossils, encasing the blocks in plaster and driving them to the National Museum of Ethiopia in Addis Ababa. In the museum lab, White painstakingly injected glue from syringes into each fragment and then used dental tools and brushes, often under a microscope, to remove the silty clay from the glue-hardened fossils. Meanwhile, Suwa, today a paleoanthropologist at the University of Tokyo, analyzed key fossils with modified CT scanners to see what was inside them and used computer imaging to digitally restore the crushed skull. Finally, he and anatomist C. Owen Lovejoy worked from the fossils and the computer images to make physical models of the skull and pelvis.

It’s a measure of the particularity, complexity and thoroughness of the researchers’ efforts to understand Ardi in depth that they took 15 years to publish their detailed findings, which appeared this past October in a series of 11 papers in the journal Science. In short, they wrote that Ardi and fossils from 35 other members of her species, all found in the Middle Awash, represented a new type of early hominid that wasn’t much like a chimpanzee, gorilla or a human. “We have seen the ancestor and it’s not a chimpanzee,” says White.

This came as a surprise to researchers who had proposed that the earliest hominids would look and act a lot like chimpanzees. They are our closest living relatives, sharing 96 percent of our DNA, and they are capable of tool use and complex social behavior. But Ardi’s discoverers proposed that chimpanzees have changed so dramatically as they have evolved over the past six million years or so, that today’s chimpanzees make poor models for the last common ancestor we shared.

In his lab at Kent State University, Lovejoy recently demonstrated why Ardi is so unusual. He gently lined up four bones from Ardi’s hand on his lab bench, and he showed how they fit together in a way that allowed Ardi’s hand to bend far backward at the wrist. By comparison, a chimpanzee’s wrist is stiff, which allows the animal to put its weight on its knuckles as it moves on the ground—knuckle walking. “If you wanted to evolve Ardi’s hand, you couldn’t do it from this,” he said, waving a set of bones from a chimpanzee hand in the air. If Lovejoy is right, this means Ardi—and our upright-walking ancestors—never went through a knuckle-walking stage after they came down from the trees to live on the ground, as some experts have long believed.

As evidence that Ardi walked upright on the ground, Lovejoy pointed to a cast of her upper pelvic blades, which are shorter and broader than an ape’s. They would have let her balance on one leg at a time while walking upright. “This is a monstrous change—this thing has been a biped for a very long time,” Lovejoy said.

But Ardi didn’t walk like us or, for that matter, like Lucy either. Ardi’s lower pelvis, like a chimpanzee’s, had powerful hip and thigh muscles that would have made it difficult to run as fast or as far as modern humans can without injuring her hamstrings. And she had an opposable big toe, so her foot was able to grasp branches, suggesting she still spent a lot of time in the trees—to escape predators, pick fruit or even sleep, presumably in nests made of branches and leaves. This unexpected combination of traits was a “shocker,” says Lovejoy.

He and his colleagues have proposed that Ardi represents an early stage of human evolution when an ancient ape body plan was being remodeled to live in two worlds—in the trees and on the ground, where hominids increasingly foraged for plants, eggs and small critters.

The Ardi research also challenged the long-held views that hominids evolved in a grassy savanna, says Middle Awash project geologist Giday WoldeGabriel of Los Alamos National Laboratory. The Ardi researchers’ thorough canvassing—“You crawl on your hands and knees, collecting every piece of bone, every piece of wood, every seed, every snail, every scrap,” White says—indicates that Ardi lived in woodland with a closed canopy, so little light reached grass and plants on the forest floor. Analyzing thousands of specimens of fossilized plants and animals, as well as hundreds of samples of chemicals in sediments and tooth enamel, the researchers found evidence of such forest species as hackberry, fig and palm trees in her environment. Ardi lived alongside monkeys, kudu antelopes and peafowl—animals that prefer woodlands, not open grasslands.

Ardi is also providing insights into ancient hominid behavior. Moving from the trees to the ground meant that hominids became easier prey. Those that were better at cooperating could live in larger social groups and were less likely to become a big cat’s next meal. At the same time, A. ramidus males were not much larger than females and they had evolved small, unsharpened canine teeth. That’s similar to modern humans, who are largely cooperative, and in contrast to modern chimpanzees, whose males use their size to dominate females and brandish their dagger-like canines to intimidate other males.

As hominids began increasingly to work together, Lovejoy says, they also adopted other previously unseen behaviors—to regularly carry food in their hands, which allowed them to provision mates or their young more effectively. This behavior, in turn, may have allowed males to form tighter bonds with female mates and to invest in the upbringing of their offspring in a way not seen in African apes. All this reinforced the shift to life on the ground, upright walking and social cooperation, says Lovejoy.

Not everyone is convinced that Ardi walked upright, in part because the critical evidence comes from her pelvis, which was crushed. While most researchers agree that she is a hominid, based on features in her teeth and skull, they say she could be a type of hominid that was a distant cousin of our direct ancestor—a newfound offshoot on the human family tree. “I think it’s solid” that Ardi is a hominid, if you define hominids by their skull and teeth, says Rick Potts, a paleoanthropologist at the Smithsonian’s National Museum of Natural History. But, like many others who have not seen the fossils, he has yet to be convinced that the crushed but reconstructed pelvis proves upright walking, which could mean that Ardi might have been an extinct ape that was “experimenting” with some degree of upright walking. “The period between four million to seven million years is when we know the least,” says Potts. “Understanding what is a great ape and what is a hominid is tough.”

As researchers sort out where Ardi sits in the human family tree, they agree that she is advancing fundamental questions about human evolution: How can we identify the earliest members of the human family? How do we recognize the first stages of upright walking? What did our common ancestor with chimpanzees look like? “We didn’t have much at all before,” says Bill Kimbel, an Arizona State University paleoanthropologist. “Ardipithecus gives us a prism to look through to test alternatives.”

After Ardi’s discovery, researchers naturally began to wonder what came before her. They didn’t have long to wait.

Starting in 1997, Haile-Selassie, now at the Cleveland Museum of Natural History, found fossils between 5.2 million and 5.8 million years old in the Middle Awash. A toe bone suggested its owner had walked upright. The bones looked so much like a primitive version of A. ramidus he proposed these fossils belonged to her direct ancestor—a new species he eventually named Ardipithecus kadabba.

In 2000, Martin Pickford of the College of France and Brigitte Senut of the National Museum of Natural History in Paris announced their team had found an even older hominid󈟝 fossils representing a species that lived six million years ago in the Tugen Hills of Kenya. Two of the fossils were thighbones, including one that provided the oldest direct evidence of upright walking in a hominid. They named this creature Orrorin tugenensis, drawing on a Tugen legend of the “original man” who settled the Tugen Hills. Informally, in honor of its year of discovery, they called it Millennium man.

Hot on the heels of that discovery came the most surprising one of all—a skull from Chad, about 1,500 miles west of the Great Rift Valley of eastern Africa where many of the most ancient hominids have been found. A Chadian student named Ahounta Djimdoumalbaye picked up a ball of rock on the floor of the Djurab Desert, where windstorms blow sand dunes like waves on a sea and expose fossils buried for millions of years. When Djimdoumalbaye turned over the stone, he stared into the vacant eye sockets of an ape-like face—the skull of a primate that lived six million to seven million years ago on the shores of an ancient lake. It had traits that suggested it was a hominid—a small lower face and canines and a skull that seemed to sit atop its spine, as in upright walkers. Paleontologist Michel Brunet, then of the University of Poitiers in France, introduced it as the oldest known hominid, Sahelanthropus tchadensis. (Its nickname is Toumaï, which means “hope of life” in the Goran language.) But proving that a skull walked upright is difficult, and questions linger about whether Sahelanthropus is a bona fide hominid or not.

Taken together, fossils discovered over the past 15 years have provided snapshots of several different creatures that were alive in Africa at the critical time when the earliest members of the human family were emerging. When these snapshots are added to the human family album, they double the time researchers can see back into our past—from Lucy at 3.2 million years to Toumaï at almost 7 million years.

One of the most sought-after fossils of that distant era was Lucy’s direct ancestor. In 1994, 20 years after Lucy’s skeleton was discovered, a team in Kenya led by Meave Leakey (the wife of Richard Leakey) found teeth and parts of a jaw as well as two pieces of shinbone that showed the creature walked upright. The fossils, named Australopithecus anamensis, were 4.1 million years old.

“This has been a fascinating 40 years to be in paleoanthropology,” says Johanson, “one of the great times to be in this field.” But, he adds, “there’s still enormous confusion” about the murky time before 4 million years ago.

One thing that is clear is that these early fossils belong in a class by themselves. These species did not look or act like other known apes or like Lucy and other members of Australopithecus. They were large-bodied ground dwellers that stood up and walked on two legs. But if you watched them move, you would not mistake them for Lucy’s species. They clung to life in the trees, but were poised to venture into more open country. In many ways, these early species resemble one another more than any fossils ever found before, as if there was a new developmental or evolutionary stage that our ancestors passed through before the transition was complete from ape to hominid. Indeed, when the skulls of Toumaï and Ardi are compared, the resemblance is “striking,” says paleoanthropologist Christoph Zollikofer of the University of Zurich in Switzerland. The fossils are too far apart in time to be members of the same species, but their skulls are more like each other than they are like Lucy’s species, perhaps signaling similar adaptations in diet or reproductive and social behavior.

The only way to find out how all these species are related to one another and to us is to find more bones. In particular, researchers need to find more overlapping parts of very early fossils so they can be compared directly—such as an upper end of a thighbone for both Ardi and Toumaï to compare with the upper thighbone of O. tugenensis.

At Aramis, as soon as the clan leaders gave the Middle Awash team their blessing, White began dispatching team members like an air traffic controller, directing them to fan out over the slope near Ardi’s grave. The sun was high in the sky, though, making it hard to distinguish beige bone among the bleached out sediments. This time, the team found no new hominid fossils.

But one morning later that week, the team members drove up a dry riverbed to a site on the western margin of the Middle Awash. Only a few moments after hiking into the fossil beds, a Turkish postdoctoral researcher, Cesur Pehlevan, planted a yellow flag among the cobbles of the remote gully. “Tim!” he shouted. “Hominid?” White walked over and silently examined the molar, turning it over in his hand. White has the ability to look at a tooth or bone fragment and recognize almost immediately whether it belongs to a hominid. After a moment, he pronounced his verdict: “very good, Cesur. It’s virtually unworn.” The molar belonged to a young adult A. kadabba, the species whose fossils began to be found here in 1997. Now the researchers had one more piece to help fill in the portrait of this 5.8-million-year-old species.

“There’s your discovery moment,” said White. He reflected on the fossils they’ve bagged in this remote desert. “This year, we’ve got A. kadabba, A. anamensis, A. garhi, H. erectus, H. sapiens.” That’s five different kinds of hominids, most of which were unknown when White first started searching for fossils here in 1981. “The Middle Awash is a unique area,” he said. “It is the only place on the planet Earth where you can look at the full scope of human evolution.”

The Mosaic of Humankind

Given the Jebel Irhoud fossils’ modern faces and primitive braincases, Hublin and his team suggest that the features associated with modern humans probably didn’t evolve all at once. Instead, various traits we associate with anatomically modern humans probably appeared in a type of “mosaic evolution” that Neanderthals also seem to have exhibited.

Modern humankind “wasn’t a new model of an automobile that appeared in a showroom with all the bells and whistles,” says Wood. “Different parts of modern human morphology and behavior probably came incrementally.”

The find also shows how the precursors to modern humans could have dispersed widely across Africa, Hublin’s team says. For instance, perhaps they spread into northern Africa during periodic “green Sahara” events, when the forbidding desert sometimes gave way to more hospitable grassland.

However, Hublin and his coauthor Shannon McPherron emphasize that they cannot yet say precisely where modern humans evolved on the continent.

In addition, the finds present an intriguing dilemma: Should paleoanthropologists treat the Jebel Irhoud remains as part of the Homo sapiens species?

“The material from Jebel Irhoud adds to the debate about where anthropologists should draw the line about how ‘human’ something needs to be to call it a ‘modern human,’” says Tanya Smith, a paleoanthropologist at Harvard University and Australia’s Griffith University who wasn’t involved with the new studies.

For instance, John Hawks, a paleoanthropologist at the University of Wisconsin-Madison, is concerned about the study authors' claims that the Moroccan fossils belong to the Homo sapiens clade.

“These papers are going a step too far, I think,” he says. “They redefine the concept of Homo sapiens by creating this category of ‘early modern humans’ that I’ve never seen before.”

While Hawks applauds the researchers for their careful re-excavations, he also cautions against overplaying the papers’ significance.

“Many scientists have noted the very archaic features of the [Jebel Irhoud] braincase, and some more similarities with modern humans in the face,” he adds by email. Hublin and his colleagues “really aren’t adding anything new except the date.”

For Wood, though, Hublin’s use of “early modern humans” makes sense. And regardless of precise labels, he says, the Jebel Irhoud fossils have their place in the tapestry of humankind.

“Three hundred thousand years ago, there is fossil evidence of a population that in a remarkable number of ways resembles modern humans, and you can make of that what you like,” says Wood.

“You can either expand the definition of Homo sapiens to include [Jebel Irhoud], or these were creatures that were on their way to [becoming] modern humans.”

Equality and polyamory: why early humans weren't The Flintstones

A study released last week presented evidence that prehistoric men and women lived in relative equality. But is the truth even further from the nuclear narrative?

The “standard narrative of prehistory” presents the idea that, like Fred and Wilma, men have always gone out to hunt/work and women care for home and children. Photograph: Everett Collection/Rex Features

The “standard narrative of prehistory” presents the idea that, like Fred and Wilma, men have always gone out to hunt/work and women care for home and children. Photograph: Everett Collection/Rex Features

Last modified on Wed 14 Feb 2018 21.30 GMT

Last week, scientists from University College London released a paper presenting evidence that men and women in early society lived in relative equality. The paper challenges much of our understanding of human history, a fact not lost on the scientists. Mark Dyble, the study’s lead author, stated “sexual equality is one of the important changes that distinguishes humans. It hasn’t really been highlighted before.”

Despite Dyble’s comments, however, this paper isn’t the first foray into the issue. In fact, it represents another shot fired in a debate between scientific and anthropological communities that has been raging for centuries. It’s a debate that asks some fundamental questions: who are we, and how did we become the society we are today?

Our modern picture of prehistoric societies, or what we can call the “standard narrative of prehistory” looks a lot like The Flintstones. The narrative goes that we have always lived in nuclear families. Men have always gone out to work or hunt, while women stayed at home to look after the house and the children. The nuclear family and the patriarchy are as old as society itself.

The narrative is multifaceted, but has strong roots in biological science, which can probably be traced back to Charles Darwin’s theory of sexual selection. Darwin’s premise was that due to their need to carry and nurture a child women have a greater investment in offspring than men. Women are therefore significantly more hesitant to participate in sexual activity, creating conflicting sexual agendas between the two genders.

This creates a rather awkward situation. With women producing such “unusually helpless and dependent offspring”, they require a mate who not only has good genes, but is able to provide goods and services (i.e. shelter, meat and protection) to the woman and her child. However, men are unwilling to provide women with the support they require unless they have certainty the children are theirs — otherwise they are providing support to the genes of another man. In turn men demand fidelity an assurance their genetic line is being maintained.

Helen Fisher calls this ‘The Sex Contract’, but the authors of Sex at Dawn, Christopher Ryan and Cacilda Jethá, are a little more cutting in their analysis: “the standard narrative of heterosexual interaction boils down to prostitution: a woman exchanges her sexual services for access to resources … Darwin says your mother’s a whore. Simple as that.”

Herein, so some scientists say, lie the roots of our nuclear family and the patriarchy. Our gendered hierarchy is based on an innate biological need for women to be supported by men. The very capacity for women to give birth to children places them in a lower position within society.

Scientists use a whole range of other evidence to support this narrative. Many for example point our closest relatives. Scientists have researched monogamy of gibbons and the sexual hierarchies of chimpanzees to point to a “natural” expression of our innate desires.

Other scientists use human biology. A common example is women’s apparently weak libido. Discussing his book Why Can’t a Woman be More Like a Man? released last year, for example, Lewis Wolpert states: “About half of men think about sex every day or several times a day, which fits with my own experience, while only 20 per cent of women think about sex equally often. Men are far more likely to be sexually promiscuous, a throwback to evolution where procreation was all-important.”

If you subscribe to the theory of a sex contract this is logical. A lower sex drive ensures women are more selective in their sexual decisions, making certain that they only mate with high-quality men. Women, so some scientists say, are evolutionarily designed to be selective in their mates.

Yet, for centuries many have questioned the logic, and the biology, of the standard narrative.

The first real splash in this arena came from the anthropologist Lewis Morgan, and his book Ancient Society. In the book Morgan presented the results of his study of the Iroquois, a Native American hunter-gatherer society in upstate New York. The Iroquois, Morgan observed, lived in large family units based on polyamorous relationships, in which men and women lived in general equality.

Morgan’s work hit a broader audience when it was taken up by Friedrich Engels (most famous for being the co-author of the The Communist Manifesto) in his book The Origin of Family, Private Property and the State. Engels drew on Morgan’s data, as well as evidence from around the world to argue that prehistoric societies lived in what he called “primitive communism”. Other anthropologists now call this “fierce egalitarianism”: societies where families were based on polyamory and in which people lived in active equality (i.e. equality is enforced).

Morgan and Engels were not painting a picture of a “noble savage”. Humans were not egalitarian nor polyamorous because of their social conscience, but because of need. Hunter-gather societies were based largely on small roaming clans where men engaged in hunting, while women’s roles focused around gathering roots, fruit and berries, as well as looking after the “home”. In these societies community was everything. People survived through the support of their clan and therefore sharing and working within their clan was essential. This crossed over into sex as well.

Polyamory helped foster strong networks, where it became everyone’s responsibility to look after children. As Christopher Ryan states: “These overlapping, intersecting sexual relationships strengthened group cohesion and could offer a measure of security in an uncertain world.” The same can be said for our other social hierarchies. As Jared Diamond explains, with no ability or need to store or hoard resources, “there can be no kings, no class of social parasites who grow fat on food seized from others”. Hunting and gathering enforced social equality. It was the only way people could survive.

While initially developed in the 1800s, these theories died down somewhat in the early 20th century. With Engels’ connection to Marx, many of these ideas were lost in the great philosophical debate of the Cold War. Many second wave feminists, led primarily by Simone de Beauvoir in her book The Second Sex, also argued against Engels’ ideas.

Recently however, these theories have had something of a renaissance. On top of Dyble’s study last week, new anthropological and scientific evidence backs up this challenge to the standard narrative. In 2012 Katherine Starkweather and Raymond Hames conducted a survey of examples on ‘non-classical polyandry’, discovering the phenomenon existed in many more societies than previously thought.

In another example Stephen Beckman and Paul Valentine examined the phenomenon of ‘partible paternity’ in tribes in South America: the belief that babies are made up from the culmination of the spermatozoa of multiple males. This belief, which is common in tribes in the Amazon requires polyamorous sexual activity by women, and that men share the load of supporting children.

And then there is the example of the Mosua in China, a society in which people are highly promiscuous and where there is no shame associated with this. Mosua women have a high level of authority, with children being looked after by a child’s mother and her relatives. Fathers have no role in the upbringing of a child — in fact the Mosua have no word to express the concept of “father”.

In Sex at Dawn, released in 2010, Ryan and Jethá provided a range of biological evidence to back up this anthropological data. Let’s take a look at their counteractions to the two examples produced earlier: the behaviour of our closest relatives and women’s apparently low libido.

Ryan and Jethá argue that while yes, gibbons and chimpanzees are close relatives, our closest relatives are in fact bonobos. Bonobos live in female-centered societies, where war is rare and sex serves an important social function. They are polyamorous, with both male and female apes having regular sex with multiple partners. This looks more like the societies Morgan and Engels were describing.

When it comes to women’s “low libido”, Ryan and Jethá simply disagree, arguing in fact that women have evolved for sex with multiple partners. They look, for example, at women’s ability to have multiple orgasms in a sexual session, to have sex at any time during their menstrual cycle and their propensity to make a lot of noise during sex — which they argue is a prehistoric mating call to encourage more men to come and join in. These evolutionary traits have occurred, they argue, to ensure breeding is successful.

In short, Dyble’s paper is unlikely to provide the conclusion to a battle that has been raging for at least two centuries. The paper, however, certainly is another nail in the coffin of the standard narrative of prehistory. One this seems clear: our history is much more complex than previously thought. How complex, we may never know. Without a time machine it is impossible to confirm. But we now can be certain that things in the past were very different to the standard narrative. We are not all just versions of the modern stone age family.

The Things We Can’tKnow

There are gaps in our knowledge about early Homo sapiens that probably won’t ever be filled.

Was There Religion?

Yes, but we can’t know much about our ancestors’ fictions. We can make guesses about their beliefs, but those guesses often say more about our modern biases than about what foragers thought and felt.


Most experts agree that early Homo sapiens were animists rather than theists.

  • Animism: The belief that every animate and inanimate thing has thoughts and feelings and can communicate with people. This belief system is non-hierarchical—all beings are equal.
  • Theism: The belief in a god or gods that are above us in status and create the universal order of our world. This belief system is hierarchical—divine beings outrank non-divine beings.

Our forager ancestors probably believed that all animate things (mice, deer, and spirits) and inanimate things (rocks, rivers, and trees) had feelings and desires. They also had the capability to reward or punish early Homo sapiens for their actions.

Because animism is non-hierarchical, there were no walls separating people from the rest of the natural world. People were not of a higher status than other animals, plants, spirits, and inanimate objects. Early Homo sapiens didn’t believe that spirits, trees, and animals existed to serve or please them.

Animism doesn’t refer to a particular religion. Within this general concept, there were probably many religions practiced and beliefs believed by foragers.

Evidence of Early Fictions

Although we don’t know what early Homo sapiens believed, we do know that they had fictions.

For example, in Russia, archeologists discovered burial site containing numerous graves. Most of the graves were unnotable, but one contained the skeletons of two children, a boy and a girl. The children were adorned with thousands of ivory beads and fox teeth and were surrounded by statuettes and other ivory objects.

Carving the beads alone would have involved 7,500 hours of work. It was clear that there was something special about these kids. But these kids were too young to have achieved prominence in their band by being great leaders or hunters.

We don’t know why they were special, but it’s clear that this band held some kind of imaginary reality that gave the children status beyond their DNA or their ability to help the band survive and procreate.

Even though we’ll never know what our ancestors believed, what their social structures looked like, or what political strife occurred, it’s crucial that we speculate. If we don’t ask how foragers shaped our current world, we might assume that they didn’t. But, as we’ll see in the next chapter, Sapiens after the Cognitive Revolution reshaped the natural and social worlds around them, legacies we still grapple with today.

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  • What the future of humanity might look like

Amanda Penn

Amanda Penn is a writer and reading specialist. She’s published dozens of articles and book reviews spanning a wide range of topics, including health, relationships, psychology, science, and much more. Amanda was a Fulbright Scholar and has taught in schools in the US and South Africa. Amanda received her Master's Degree in Education from the University of Pennsylvania.

A Brief History of Human Sex

Birds do it, bees do it, humans since the dawn of time have done it.

But just how much has the act really changed through the millennia and even in past decades? Are humans doing it more? Are we doing it better? Sort of, say scientists. But it's how people fess up to the truth about their sex lives that has changed the most over the years.

Humans have basically been the same anatomically for about 100,000 years—so what is safe to say is that if we enjoy it now, then so did our cave-dwelling ancestors and everyone else since, experts say.

"Just as our bodies tell us what we might like to eat, or when we should go to sleep, they lay down for us our pattern of lust," says University of Toronto psychologist Edward Shorter. "Sex has always offered pleasure."

Sexuality has a lot to do with our biological framework, agreed Joann Rodgers, director of media relations and lecturer at Johns Hopkins Medical Institutions.

"People and indeed all animals are hard wired to seek out sex and to continue to do so," Rodgers said in a recent interview. "I imagine that is evidence that people at least like sex and even if they don't they engage in it as a biological imperative."

It is nearly impossible to tell, however, whether people enjoyed sex more 50 years ago or 50,000 years ago, said David Buss, professor of psychology at the University of Texas and author of "The Evolution of Desire: Strategies of Human Mating" (Basic Books, 2003).

There is "no reason to think that we do more now than in the past, although we are certainly more frank about it," Buss told LiveScience.

Indeed, cultural restraints—rather than anything anatomical—have had the biggest effect on our sexual history, Shorter says.

"To be sure, what people actually experience is always a mixture of biological and social conditioning: Desire surges from the body, the mind interprets what society will accept and what not, and the rest of the signals are edited out by culture," he writes in his book, "Written in the Flesh: A History of Desire" (University of Toronto Press, 2005).

That's not to say that cultural norms keep people from exploring the taboo, but only what is admitted to openly, according to archaeologist Timothy Taylor of Great Britain's University of Bradford.

"The idea that there is a sexual line that must not be crossed but in practice often is, is far older than the story of Eve's temptation by the serpent," he writes in "The History of Sex: Four Million Years of Human Sexual Culture" (Bantam Books, 1996).

Modern advances

Religion especially has held powerful sway over the mind's attitude towards the body's carnal desires, most sexual psychologists agree. Men and women who lived during the pious Middle Ages were certainly affected by the fear of sin, Shorter said, though he notes there were other inhibiting factors to consider, too.

"The low priority attached to sexual pleasure by people who lived in distant times is inexplicable unless one considers the hindrances that existed in those days," Shorter writes. He points especially to the 1,000 years of misery and disease—often accompanied by some very un-sexy smells and itching—that led up to the Industrial Revolution. "After the mid-nineteenth century, these hindrances start to be removed, and the great surge towards pleasure begins."

Many historians and psychologists see the late 1800s as a kind of watershed period for sexuality in the Western world. With the industrial revolution pushing more and more people together—literally—in dense, culturally-mixed neighborhoods, attitudes towards sex became more liberal.

The liberalization of sexuality kicked into high gear by the 1960s with the advent of the birth control pill, letting women get in on the fun and act on the basis of desire as men always had, according to Shorter.

"The 1960s vastly accelerated this unhesitant willingness to grab sex for the sheer sake of physical pleasure," he said, noting that the trend of openly seeking out sex just because it feels good, rather than for procreation alone, has continued on unabated into the new millennium.

Global variations

But despite the modern tendency towards sexual freedom, even today there are vast differences in attitudes across the world, experts say.

"Cultures vary tremendously in how early they start having sex, how open they are about it, and how many sexual partners they have," said Buss, noting that Swedes generally have many partners in their lifetime and the Chinese typically have few.

An informal 2005 global sex survey sponsored by the condom company Durex confirmed Buss' views. Just 3 percent of Americans polled called their sex lives "monotonous," compared to a sizable 26 percent of Indian respondents. While 53 percent of Norwegians wanted more sex than they were having (a respectable 98 times per year, on average), 81 percent of the Portuguese were quite happy with their national quota of 108 times per year.

Though poll numbers and surveys offer an interesting window into the sex lives of strangers, they're still constrained by the unwillingness of people to open up about a part of their lives that's usually kept behind closed doors.

And what if we weren't bound by such social limitations? Taylor offers the promiscuous—and very laid-back—bonobo chimpanzee as a utopian example.

"Bonobos have sex most of the time . a fairly quick, perfunctory, and relaxed activity that functions as a social cement," he writes. "But for cultural constraints, we would all behave more like bonobos. In physical terms, there is actually nothing that bonobos do that some humans do not sometimes do."

Watch the video: Älteste Frühmenschen-DNA verblüfft Forscher (January 2022).