At a research site in Fongoli, Senegal, a female chimpanzee breaks off a branch, chews the end to make it sharp, then uses this rudimentary spear to skewer a tasty bushbaby hiding inside a hollow tree. The footage represents an astonishing breakthrough for primate researchers: It's the first time anyone has documented a chimpanzee wielding a carefully prepared, preplanned weapon.
But it's only the latest in a slew of extraordinary new findings about ape behavior. The more researchers learn about the great apes—chimpanzees, bonobos, gorillas, and orangutans—the more evidence they find of creative intelligence. What, then, is the essential difference between us and them? "Ape Genius," a NOVA-National Geographic special, explores that provocative question and examines research that is illuminating the ape mind.
The spear-wielding chimps were documented by anthropologist Jill Pruetz of Iowa State University, who also observed the Fongoli colony doing something else never documented before: holding a pool party. Chimps were long thought to be afraid of water, but as charming poolside footage reveals, these hairy bathers swing from the trees and take the plunge in high spirits.
In addition to Pruetz, "Ape Genius" features contributions by other noted researchers, including Brian Hare of Duke University, Andrew Whiten of the University of St. Andrews, Tetsuro Matsuzawa of Kyoto University, Rebecca Saxe of the Massachusetts Institute of Technology, and Josep Call and Michael Tomasello of the Max Planck Institute for Evolutionary Anthropology.
Bit by bit, these investigators are converging on an explanation for why the non-human great apes never made the breakthrough into an accelerating human-style culture that builds on the achievements of previous generations. After all, apes are stronger and more agile than we are. They have also shown previously unsuspected talents for reasoning, creative problem solving, and other intelligent traits. Some have even demonstrated rudimentary language abilities. And their emotional lives seem on a par with ours, as is evident in moving footage of a mother chimp dealing with the sickness and death of her child.
But something has held them back. What?
"Ape Genius" takes viewers to the African savannah and research labs in Texas, Germany, and Japan to explore a number of fascinating new experiments that shed light on just what apes are thinking.
Through careful design, such tests spotlight different features of the ape mind, and striking variation between one species and another. For example, bonobos appear far more cooperative than chimps and will work together on a simple task that yields a box of food to split. Chimps are more selfish under such circumstances, but they appear to have a code of conduct and will seek revenge when they have been wronged intentionally.
One of the program's most startling experiments suggests that chimps can easily outsmart young children. In this test, toddlers follow a series of steps shown to them by an adult teacher to obtain a piece of candy. Some of the steps are clearly unnecessary and nonsensical, but the toddlers mindlessly follow every stage of the instructions. In contrast, chimps cut out the unnecessary steps and get the candy quickly. Yet the chimps' greater cunning can't disguise an important implication of the experiment: We humans have a built-in expectation that others are trying to teach us—an expectation that may have played a vital role in the unique growth of human intelligence.
Something as simple as a common gesture—pointing—marks another key difference between apes and humans. Apes don't seem to relate to the act of communication involved when a researcher points at an object. They can't understand it as a request to attend to the same object, and therefore they miss out on a crucial link in the learning process.
Ultimately, such gaps between humans and apes—the little differences that make the big difference—may explain why we study them and not the other way around.
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