Chimpanzee-Baboon Differences

When wild chimpanzees want a protein snack, they may choose to go after termites. The apes’ method of termite-hunting is cultural—that is, dependent on ape-to-ape learning in the specific population in which they live. Chimpanzees in Gombe, Tanzania, for instance, “fish” for termites by making a wand tool and then sticking it down into the termite mound. Chimpanzees in the Nouabalé-Ndoki National Park in the Republic of Congo, by contrast, first push a puncturing tool with their feet into the mound and only then use finer manual skills to probe with tools into the termite chambers.

Baboons supplement their diet with termites, too. Watching them leap into the air when the termites fly out of the mound shows they’re enthusiastic termite consumers. But the baboons don’t use tools to hunt these insects. In fact, they’re stuck waiting around for the termites’ seasonal flights from the mound, and then catch the insects by hand. In other words, the monkeys’ diet is constrained by the termites’ reproductive biology, and the chimpanzees play an active role, aided by technology, in tapping into a nutritious food source on their own schedule.

This chimpanzee-baboon difference illustrates what some primatologists call the “cognitive watershed”: the idea that, as a pattern, our closest living relatives, the great apes (chimpanzees, bonobos, gorillas, and orangutans), are more highly skilled at problem solving and complex thinking than are the monkeys (baboons, macaques, howler monkeys, squirrel monkeys, and their relatives).

The cognitive watershed idea is best considered a hypothesis rather than a robust conclusion. After all, monkeys, like baboons—and vervets and macaques—show keen intelligence in their own ways. When vervet monkey A aggresses against vervet monkey B, B will be highly likely to carry out what’s called “kin-based redirected aggression.” That is, B may soon go after A’s relative and punish the relative for A’s transgression. That shows abstract thinking about monkey relatedness.

But the great apes seem to go even further than this. They show evidence of an elaborated theory of mind—an ability to take into account that their social partners may have access to different stores of knowledge than they themselves do. Ape tool behavior once again provides a good example. In Cote d’Ivoire, a mother chimpanzee is likely to facilitate her youngster’s learning of nut-cracking in a number of ways directly related to what that youngster does or doesn’t already know about bringing together nuts, hammers, and anvils. The mother adjusts her behavior to the visible skill level of the child, implicitly recognizing that she herself knows more than the youngster and that the youngster’s abilities shift over time.

Capuchin monkeys of South America push against the cognitive watershed idea quite directly because they forage aided by tools in complex ways that are quite unusual for monkeys. Of course, caution is required on the part of scientists who compare the cognition of two groups of nonhuman primates like this—especially because we humans may tend to rate apparently humanlike thinking as the most complicated of all.

Still, the cognitive watershed is a useful perspective because it helps primatologists think up experiments and predictions to test, and helps us organize how we approach potentially key distinctions within the primate order.

Barbara King is a professor of anthropology at The College of William & Mary and the author of Being With Animals and the Friday Animal Blog.

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