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MAY 10,1998 11:59 EDT
Researchers Rethink Origin of Human Mind
By LAURAN NEERGAARD ATLANTA (AP) -- Bill Hopkins put 10 different species of monkeys and apes into an MRI scanner and came to a startling conclusion: Apes share a brain feature thought to make humans unique. Fellow scientist Frans de Waal sees the roots of cognition in a bonobo named Kakowet, who spotted zookeepers turning on water valves and realized they would flood a nearby moat where infant apes were playing. Kakowet warned the zookeeper and helped rescue the babies. The nation's largest primate research center is bringing together neuroscientists, geneticists and behavior experts to shed new light on human evolution: Using our closest living relatives -- the apes -- to explain how human cognition and behavior evolved. "By understanding chimps, maybe we'll understand ourselves a wee bit better," explained Tom Insel, chief of the Yerkes Regional Primate Center, which is setting up the Living Links project on human evolution. Scientists once largely excluded research on mental traits from the study of evolution, instead emphasizing fossils that showed how human anatomy had developed over millions of years. But now so-called evolutionary psychology is hot -- and if early work is any indication, human mental traits may not be so unique. Take Hopkins' finding that apes are left-brained like humans, or de Waal's experiments that suggest certain primates developed frameworks for morality. It's a controversial field, but one that should help generate new insights into "why the mind was organized the way it was," said Marc Hauser, who researches evolutionary neurobiology at Harvard University. "Animals enter the debate in a way that's very important. It's not just that they're cute and fun to watch on the evening news," but that they help define theories about the human mind, he said. "And that's critical." The idea behind Living Links is to use Yerkes' 200 chimpanzees and more than 2,500 other primates to help move these theories from speculation to science. One chief project will be identifying ape genes to match with the neurologic and behavior findings. Human DNA is 98.4 percent identical to the DNA of chimps and bonobos, a lesser-known chimp-like ape. "What is it in that other 1.6 percent that makes us different from them? That's the critical question," said de Waal, a renowned primatologist who will direct Living Links. Language is one critical difference. Humans are "left brained" -- the planum temporale that controls language is much larger on the left. (Laymen may know the term because the left brain also controls right-handedness.) Hopkins' brain scans found that orangutans, gorillas, chimps and bonobos all were left-brained, too. Monkeys, lower on the evolutionary scale, were not. "We were able to pinpoint in evolutionary time when this evolved," explained Hopkins. Of course, apes don't speak. So Hopkins' excited colleagues immediately began testing what the discovery means. They gave language-related tasks to chimps trained to communicate via computer, monitoring them with PET scans that light up the brain cells being used. They're now comparing results with human PET scans to see if the chimps used the same brain region as people doing the same task. In addition, bonobos gesture almost exclusively with their right hands -- harking back to that right-hand, left-brain connection in humans. "Maybe language came from gesticulation," de Waal suggested. De Waal's own research is more controversial: He sees roots of complex cognition and even morality in the behavior of both apes and monkeys. Remember Kakowet, who stopped zookeepers from accidentally drowning baby bonobos? The ability to look at the world through someone else's perspective -- in this case, to realize the babies would be in the path of rushing water and cannot swim -- is incredibly advanced thinking once thought unique to humans, he explained. And human morality arose from the simple need to get along in order to survive, theorizes de Waal. Already well-known for extensive research on how monkeys and apes reconcile after conflict, de Waal now is studying morality in their system of tit-for-tat sharing. De Waal puts two capuchins, the crewcut monkeys of organ grinder fame, into side-by-side cages. They can see a tasty cup of apples and carrots nearby. But only if the two monkeys cooperate, pulling together on a heavy pole, will one be able to reach the treats. Will he pass some through the bars to his helper, or get a reputation as greedy and be ostracized? "Cooperative hunting may be a secret to a lot of things humans do," de Waal says with a grin. "Corporate life is not so different, eh?" To find out more about bonobos, check out
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