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  • In 1924, a worker at a limestone quarry in the town of Taung, South Africa made an incredible

  • discovery.

  • It was the fossilized skull of a juvenile hominin, a member of the human lineage that

  • includes us and all of our ancestors that came after our split with chimpanzees and

  • bonobos.

  • That little skull became the type specimen for Australopithecus africanus, and it would

  • become one of the most important fossils in the study of human evolution.

  • Today, the specimen is known as the Taung Child.

  • Its discovery revolutionized our thinking about our past for a number of reasons.

  • For one thing, at about 2.8 million years old, it was the first fossil evidence that

  • our early human ancestors originated in Africa.

  • But there was something else.

  • The skull had been found among lots of bones from other, mostly small animals, and many

  • of them had been badly damaged, as if the animals had been butchered.

  • So for decades, these fossils were read by experts as evidence that hominins like Australopithecus

  • weren’t fruit-eating apes -- they were carnivorous hunters, so-calledpredatory ape-men.”

  • It would be more than 80 years before scientists would realize that, in fact, the Taung site

  • was not proof that australopithecines were hunters.

  • Instead, it was actually evidence that the hominins themselves were being hunted.

  • No one noticed it at the time, but the skull of the Taung Child bore the telltale marks

  • of violent trauma: puncture holes in the base of the eye sockets, a depressed fracture in

  • the top of the skull, and scratches on the sides.

  • These would eventually prove to be the hallmarks of a predator that no one suspected.

  • But this child’s skull is just one example of the evidence that, not too long ago, our

  • early human ancestors were under constant threat of attack from predators.

  • And it turns out that this difficult chapter in our history may be responsible for the

  • adaptations that allowed us to become so successful.

  • We may be who we are today, because of the time when we were prey.

  • The notion that our ancestors were once hunted by other animals would have come as a surprise

  • to the anthropologist who first studied the Taung Child.

  • His name was Raymond Dart, and he proposed that one of the driving forces of human evolution

  • was what he calledthe thirst for blood.”

  • To Dart and many anthropologists of his time, the impulse to kill prey was seen as a deeply

  • ingrained part of our heritage.

  • Dart observed baboons that appeared tospontaneouslyhunt down prey, and he noted that living hunter-gatherers

  • seemed to be hunters first and gatherers second.

  • So, Dart built the case that australopithecines were ravenous carnivores, as more and more

  • fossils emerged that seemed to support his model.

  • One such fossil was unearthed in a South African cave in 1949: the bony skullcap of a juvenile

  • hominin with two very suspicious puncture marks.

  • This partial cranium belonged to a young member of Paranthropus robustus dating to between

  • 1.8 and 1.5 million years ago.

  • It was found alongside other fossil mammals, like antelope and baboons, many of which were

  • also damaged or had only their skulls preserved.

  • The child’s skull was labelled SK 54, and it had suffered two punctures at the back

  • of the head.

  • And the bone on the inside of the cap, where those punctures were, flaked upward - indicating

  • that the victim was probably alive, or only very recently dead, when it was attacked.

  • At the time, a science writer named Robert Ardrey took this fossil as evidence of interpersonal

  • violence: SK 54, he said, was the victim of two blows to the back of the head with a pointed

  • object, by another hominin.

  • Soon, the idea began to take hold that our evolution was deeply shaped by violence, including

  • between humans.

  • Ardrey gave this idea the rather sensational name ofThe Killer Ape Theory.”

  • Dart described it asthe predatory transition from ape to man.”

  • And this view seemed to get another big boost from a discovery made at a South African cave

  • site called Makapansgat.

  • The cave was found to be filled with the bones of Australopithecus africanus and many other

  • mammals - most of which, like at the Taung site, were broken.

  • Raymond Dart studied more than 7000 remains from this site and was struck by the fact

  • that the fossils consisted almost entirely of skulls and neck vertebrae.

  • So he concluded that the fractures on these bones were evidence of blows by hunters and

  • that the high proportion of skulls meant that the hominins were taking the heads of

  • their prey as trophies -- including the heads of their own species.

  • But within the field of anthropology, changes were in the works.

  • Just as the Killer Ape Theory was reaching its peak of popularity, more scientists began

  • to suspect that we had actually spent most of our evolutionary history being prey of

  • other, better hunters.

  • Enter the American anthropologist Sherwood Washburn.

  • While doing research on a game reserve in Africa, he noticed how modern predators ate

  • carcasses selectively - eating the soft, meaty parts and leaving skulls, jaws, and upper

  • vertebrae behind.

  • It struck him that this was the same pattern of bones that Dart saw at the sites of supposed

  • homininheadhunters”.

  • Washburn also observed hyenas carrying off parts of carcasses and stashing the bones

  • around their dens - again, creating a pattern like the one Dart was seeing in the South

  • African caves.

  • Washburn published his observations in 1957, and argued that australopithecines weren’t

  • headhunters - instead, they were the prey of carnivores like hyenas.

  • This was a major turning point in our understanding of our evolutionary history.

  • For decades, Dart and his contemporaries had been studying human nature in the violent

  • social context of World Wars I and II, so it made sense that they understood our history

  • as being shaped by aggression.

  • But while they stuck to that model, younger anthropologists began to explore Washburn’s

  • ideas.

  • And his work made enough of an impact that when another damaged hominin fossil was found

  • -- this time at Olduvai Gorge, Tanzania, in 1960 -- other hominins were not considered

  • the top suspects.

  • In this case, the fossil was OH8, a slightly mangled partial left foot of Homo habilis,

  • discovered by anthropologist Louis Leakey.

  • The ankle bone had tooth marks on it, and Leakey’s wife and partner, Mary Leakey,

  • concluded the marks came from a carnivore that was probably not a hyena, but nor was

  • it another hominin.

  • So by the mid-1960s, anthropologists were at least starting to think that hominins couldve

  • been prey.

  • Then, in 1970, paleontologist C.K. Brain revisited the cave site where SK54, that skullcap with

  • the puncture wounds, had been found.

  • He wanted to try to figure out why all of those fossils had accumulated where they had.

  • And he realized that the fossils weren’t signs of hominins hunting, much less fighting

  • each other.

  • Instead, he argued, those fossils had been the victims of a hungry ancient leopard.

  • For one thing, he pointed out, modern leopards often stash their kills in the trees that

  • grow around these types of caves.

  • And the bones often end up dropping down into the caves.

  • But the more convincing evidence was that the puncture wounds in SK54 perfectly matched

  • the lower canine teeth of a leopard.

  • Which means some big cat must have attacked Sk 54, and dragged it by its head up into

  • a tree, its bones later falling into the cave.

  • So, just like with Washburn, Brain’s observations of the behavior of living carnivores were

  • fundamental to rethinking whether our hominin ancestors were the hunters or the hunted.

  • Big cats and hyenas turned out to be very good at making just the kinds of bone assemblages

  • that Dart had seen in those South African caves.

  • And once anthropologists started thinking about how bones become deposited and preserved

  • in different settings, it seemed less likely that small hominins like the australopithecines

  • were mighty, bloodthirsty killers.

  • And this new thinking eventually worked its way back to that crucial, early hominin fossil:

  • the Taung Child.

  • In 1995, researchers took another look at the fossils from that site, and noticed a

  • whole new set of clues.

  • For example, they noticed that the nature of the damage to the Taung skull was similar

  • to that found on the skulls of baboons found there.

  • And they were struck by the fact that the other bones were generally of small animals.

  • And, there were also the remains of large eggshells in the area.

  • So the team proposed that the Taung Child, along with the other animals found with it,

  • were in fact the victims of a large bird.

  • They found even more convincing evidence in 2006, when they compared the Taung Child’s

  • skull to those of modern monkeys that had been preyed upon by eagles.

  • The gouges and punctures in the base of its eye orbits matched the damage done to those

  • monkey skulls.

  • So the Taung Child was likely killed by an ancient, giant bird of prey.

  • Likewise, remember OH8, the Homo habilis foot found by the Leakeys?

  • Well in 2012, researchers took a second look at that fossil, too, and noticed something new.

  • The puncture wounds in the bone had two extra grooves in them that matched the ridges found

  • on the teeth of crocodiles.

  • Crocs are ambush predators, and those kinds of attacks leave characteristic marks and

  • patterns of damage on the bones of their prey, which, again, matched the damage done to that

  • Homo habilis.

  • Weve come a long way from Raymond Dart’s ideas about bloodthirsty hominins.

  • Today it seems that our evolution was shaped less by our need to kill than by our need

  • not to be killed.

  • After all, Africa in the Pliocene and Pleistocene was a dangerous place for our fossil ancestors

  • and relatives.

  • And with selective pressure comes adaptation and evolution.

  • So the evolutionary legacy of that time when we were prey is enshrined in our bodies today.

  • Having become larger than our ancestors, for example, has helped protect us from birds

  • and smaller mammal predators.

  • And some experts argue that becoming bipedal allowed us to better scan the horizon for

  • threats, to move quickly while carrying food or infants, and just generally look bigger.

  • Plus, with our hands freed up, we could also throw things at potential predators, which

  • chimps still do today, though not as well as we can.

  • Some experts also point out that speech has given us the ability to plan, rather than

  • to just react.

  • Living primates have alarm calls that are specific to certain predators, but speech

  • allows us to figure out in advance what to do when we hear one of those calls.

  • But, it’s worth pointing out: the Taung Child, SK54, and OH8 were all bipedal hominins

  • - and they still got eaten.

  • So other researchers have suggested that maybe our evolutionary legacy from that dangerous

  • time is simply our ability to cooperate.

  • Hominins would have needed to live in groups, and also to work together to ward off threats.

  • And studies have shown that our brains are still activated in specific ways when we do

  • things like play cooperative games, triggering our reward centers when we work together.

  • By contrast, studies of chimps have shown that they don’t help others, even when there

  • is no cost to doing so.

  • But even if all of these adaptations evolved out of a need to defend ourselves from predators,

  • they obviously didn’t work every time.

  • Researchers in Poland recently discovered the finger bones of a Neanderthal child who

  • lived just 115,000 years ago.

  • And those bones were covered with dozens of small, distinctive holes that could only have

  • come from passing through the digestive tract of a large bird.

  • So, as recently as the Late Pleistocene, our ancestors were still being preyed upon, or

  • maybe scavenged, by birds, just like the Taung Child was.

  • But being able to recognize the signs of predation in our past has marked a major shift in how

  • we think about ourselves -- one that allowed us to better understand the selective pressures

  • that helped make us who we are today.

  • Thanks as always, fam, and extra big thanks to our current Eontologists, Jake Hart, Jon

  • Ivy, John Davison Ng and everyone’s favorite hominin, STEVE!

  • Do you want to join them and have me maybe mispronounce your name and make fun of you?

  • Then go to patreon.com/eons and make your pledge!

  • Now, what do you want to learn about?

  • Leave the dude a comment, and don’t forget to go to youtube.com/eons and subscribe.

In 1924, a worker at a limestone quarry in the town of Taung, South Africa made an incredible

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当人类被捕食时(When Humans Were Prey)

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    joey joey 發佈於 2021 年 05 月 03 日
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