In 1838 Charles Darwin jotted in a notebook, "He who understands baboon would do more towards metaphysics than Locke." Fifteen years ago, following the extraordinary success of their How Monkeys See the World, Dorothy Cheney and Robert Seyfarth set out to take up Darwin's challenge. Baboon Metaphysics is their fascinating response.

Cheney and Seyfarth set up camp in Botswana's Okavango Delta, where they could intimately observe baboons and their social world. Baboons are a perfect model for such a study because they live in groups of up to 150, including a handful of males and eight or nine matrilineal families of females. Such numbers force baboons to form a complicated mix of short-term bonds for mating and longer-term friendships based on careful calculations of status and individual need. The result is enough interpersonal drama to rival Jane Austen, as the baboons make and break alliances and try to anticipate the actions of their friends and rivals, all while avoiding frequent attacks by predators.

But Baboon Metaphysics is concerned with much more than just baboons' social organization-Cheney and Seyfarth aim to fully comprehend the intelligence that underlies it. How do baboons actually conceive of the world and their place in it? Using innovative field experiments, the authors test whether baboons understand kinship relations, how they make use of vocal communication, and how they manage the stress and dangers of life in the wild. They learn that for baboons, just as for humans, family and friends hold the key to mitigating the ill effects of grief, stress, and anxiety.

Written with a scientist's precision and a nature-lover's eye, Baboon Metaphysics gives us an unprecedented and compelling glimpse into the mind of another species.

This reviewer had to be restrained from stopping people in the street to urge them to read it: they would learn something of the way science is done, something about how monkeys see their world, and something about themselves, the mental models they inhabit. - Roger Lewin, Washington Post Book World "A fascinating intellectual odyssey and a superb summary of where science stands." - Geoffrey Cowley, Newsweek"

Dorothy L. Cheney is professor of biology and Robert M. Seyfarth is professor of psychology at the University of Pennsylvania. They are the authors of How Monkeys See the World, also published by the University of Chicago Press.