LISLE, ILLINOIS--Like an oblivious dad behind the wheel, male chimps don't pay as much attention to landmarks as females do. But they can do just as well if penalized for getting things wrong, according to research presented here last week at an international ape research meeting.
Chimpanzees, our closest living relatives, can grasp the meaning of certain abstract symbols, such as numbers and the gestures of sign language, but researchers were not sure if they could create a mental map of a room or their favorite spot in the woods--a task human children can't do until they're 3 years old. To find out, psychologists Valerie Kuhlmeier and Sarah Boysen of Ohio State University in Columbus hid a juice bottle in an outdoor enclosure behind or underneath a tire, a children's sandbox, a teeter-totter, or a plastic barrel. Then, they showed chimps a scale model of the enclosure, complete with miniature hiding places, hid a miniature juice bottle in the corresponding place, and let the chimps loose in the room to find, and savor, the juice.
Once in the enclosure, the three female chimps made a beeline for the hidden treat an average of five times out of eight; the four males, however, searched the hiding places one by one. The males did better than chance when the researchers changed the rules, permitting the animals to drink the juice only if they found it on the first try. The experiments suggest that both sexes can create a mental map, but male chimps don't bother to refer to it unless it matters to them, says Kuhlmeier.
Biological anthropologist Barbara King of the College of William and Mary in Williamsburg, Virginia, says the experiment may reveal a female knack for noticing and remembering details in their surroundings. That may enable them to better care for their infants, she says, adding that the study "gives us a window into understanding what females do differently and better."
But biological anthropologist Richard Wrangham of Harvard University says the results, although "fascinating," don't necessarily tell us much about the difference between males' and females' mental maps. The males may be more confident than the females that they'll eventually get the food they want and less motivated to rush out and grab it, he says.