June 9, 1997

Human ability to 'ape'

behavior gives cognitive boost

Monkey see, monkey do? According to research conducted at Emory and Yerkes Primate Center, human children are more likely than chimpanzees to "ape" or imitate adult behavior.

In studies involving various kinds of tool use, children are much better imitators than chimps, explained Michael Tomasello, professor of psychology at Emory and affiliate scientist at Yerkes. "Children copy the way that adults do it, but chimps mainly figure it out for themselves."

Tomasello's research focuses on how children and chimps communicate and learn from others. Some of his findings are reported in a soon-to-be-released book, Primate Cognition (Oxford University Press), which he co-wrote with graduate student Josep Call.

Tomasello conducted some experiments in which children and chimpanzees were given rake-like tools that could be used in two ways to rake in objects or food. Then both the children and chimps observed a human adult use the rake in both an efficient and inefficient way.

"The human children mostly copied the techniques of the demonstrator, even when those techniques were relatively inefficient," he said. "The chimpanzees, on the other hand, mostly ignored the demonstrator, devising their own individual strategies no matter what they observed."

The chimpanzee's approach is very intelligent and might be considered more creative, he said, "but it's not quite like taking advantage of other people's knowledge. And that's what children specialize in-taking advantage of skills and knowledge that other people have."

Some of Tomasello's other studies involved the acquisition of language and communication skills. Again, he found that when children use language, they are matching what adults do, whereas chimp gestures are individual inventions.

Working with children who were 18 to 24 months old and just starting to have language skills, he used made-up words to see how children learned the meaning of the words. He found that children identified the act or object the word was supposed to represent by reading an adult's body language and emotional expression.

"Learning words depends on being able to read the intentions or infer the goals of other people," he observed, "and this kind of intention reading-goal reading-is just what chimps don't do." A number of lines of evidence reveal that chimps don't imitate gestures, but learn them individually on their own, he said. "One chimp is not copying the other one, but rather each is learning its communicative gestures through a kind of dance. They learn to do 'x' when a partner does 'y' as a complementary response, not as an imitation."

In studying these two areas-communication and the social learning of tool use-the central point is the same, Tomasello observed. "Children are really good at soaking up or plugging into what the adults are doing, either with communication-things like words-or with tools, and the chimps are finding other ways to be skillful, but not by imitating what the adults are doing."

He noted that humans have invented many things, including language, computers and other tools. "I don't think it comes from each individual person being that much smarter than each individual chimp," he said. "It comes from the fact that humans are able to pool their cognitive resources."

Each individual human child learns from other individuals and from the artifacts those individuals leave behind, such as language and tools, he explained. "Sometimes we're looking for a small difference that made a big difference, he added. "This small difference is that humans can take advantage of what other people know much better than other species, and that's what gives them the extra cognitive boost."

-Linda Klein

Return to June 9, 1997 Contents Page