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'Medical News Today
Main Category: Biology/Biochemistry News
Article Date: 20 Feb 2006 - 0:00am (UK)
Humans Evolved To Be Peaceful, Cooperative And Social
Animals, Not Predators
by Neil Schoenherr
Washington University in St. Louis
You wouldn't know it by current world events, but humans
actually evolved to be peaceful, cooperative and social animals,
not the predators modern mythology would have us believe,
says an anthropologist at Washington University in St. Louis.
Robert W. Sussman, Ph.D., professor anthropology in Arts
& Sciences, spoke at a press briefing, "Early Humans on the
Menu," during the American Association for the Advancement
of the Science's Annual Meeting at 2 p.m. on Feb. 18.
Also scheduled to speak at the briefing were Karen Strier,
University of Wisconsin; Agustin Fuentes, University of Notre
Dame; Douglas Fry, Abo Akademi University in Helsinki and
University of Arizona; and James Rilling, Emory University.
In his latest book, "Man the Hunted: Primates, Predators and
Human Evolution," Sussman goes against the prevailing view
and argues that primates, including early humans, evolved not
as hunters but as prey of many predators, including wild dogs
and cats, hyenas, eagles and crocodiles.
Despite popular theories posed in research papers and popular
literature, early man was not an aggressive killer, Sussman
argues. He poses a new theory, based on the fossil record and
living primate species, that primates have been prey for millions
of years, a fact that greatly influenced the evolution of early man.
"Our intelligence, cooperation and many other features we have
as modern humans developed from our attempts to out-smart
the predator," says Sussman.
Since the 1924 discovery of the first early humans,
australopithicenes, which lived from seven million years ago to
two million years ago, many scientists theorized that those early
human ancestors were hunters and possessed a killer instinct.
The idea of "Man the Hunter" is the generally accepted paradigm
of human evolution, says Sussman, "It developed from a basic
Judeo-Christian ideology of man being inherently evil, aggressive
and a natural killer. In fact, when you really examine the fossil
and living non-human primate evidence, that is just not the case."
Sussman's research is based on studying the fossil evidence
dating back nearly seven million years. "Most theories on Man
the Hunter fail to incorporate this key fossil evidence," Sussman
says. "We wanted evidence, not just theory.
We thoroughly examined literature available on the skulls,
bones, footprints and on environmental evidence, both of our
hominid ancestors and the predators that coexisted with them."
Since the process of human evolution is so long and varied,
Sussman and his co-author, Donna L. Hart, decided to focus
their research on one specific species, Australopithecus
afarensis, which lived between five million and two and a half
million years ago and is one of the better known early human
species. Most paleontologists agree that Australopithecus
afarensis is the common link between fossils that came before
and those that came after. It shares dental, cranial and skeletal
traits with both. It's also a very well-represented species in the
fossil record.
"Australopithecus afarensis was probably quite strong, like a
small ape," Sussman says. Adults ranged from around 3 to 5
feet and they weighed 60-100 pounds. They were basically
smallish bipedal primates. Their teeth were relatively small, very
much like modern humans, and they were fruit and nut eaters.
But what Sussman and Hart discovered is that Australopithecus
afarensis was not dentally pre-adapted to eat meat.
"It didn't have the sharp shearing blades necessary to retain and
cut such foods," Sussman says. "These early humans simply
couldn't eat meat. If they couldn't eat meat, why would they hunt?"
It was not possible for early humans to consume a large amount
of meat until fire was controlled and cooking was possible.
Sussman points out that the first tools didn't appear until two
million years ago. And there wasn't good evidence of fire until
after 800,000 years ago. "In fact, some archaeologists and
paleontologists don't think we had a modern, systematic method
of hunting until as recently as 60,000 years ago," he says.
"Furthermore, Australopithecus afarensis was an edge species,"
adds Sussman. They could live in the trees and on the ground
and could take advantage of both. "Primates that are edge
species, even today, are basically prey species, not predators,"
Sussman argues.
The predators living at the same time as Australopithecus
afarensis were huge and there were 10 times as many as today.
There were hyenas as big as bears, as well as saber-toothed cats
and many other mega-sized carnivores, reptiles and raptors.
Australopithecus afarensis didn't have tools, didn't have big teeth
and was three feet tall. He was using his brain, his agility and his
social skills to get away from these predators. "He wasn't hunting
them," says Sussman. "He was avoiding them at all costs."
Approximately 6 percent to 10 percent of early humans were
preyed upon according to evidence that includes teeth marks
on bones, talon marks on skulls and holes in a fossil cranium
into which sabertooth cat fangs fit, says Sussman. The predation
rate on savannah antelope and certain ground-living monkeys
today is around 6 percent to 10 percent as well.
Sussman and Hart provide evidence that many of our modern
human traits, including those of cooperation and socialization,
developed as a result of being a prey species and the early
human's ability to out-smart the predators. These traits did not
result from trying to hunt for prey or kill our competitors, says
Sussman.
"One of the main defenses against predators by animals without
physical defenses is living in groups," says Sussman. "In fact,
all diurnal primates (those active during the day) live in
permanent social groups. Most ecologists agree that predation
pressure is one of the major adaptive reasons for this group-living.
In this way there are more eyes and ears to locate the predators
and more individuals to mob them if attacked or to confuse them
by scattering. There are a number of reasons that living in groups
is beneficial for animals that otherwise would be very prone to
being preyed upon."
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