The laughter depends on the underlying assumption that while apes may look like humans, akin even to the most powerful leader in the world, there still must be a quantum leap from them to us. But the laughter grows thinner by the year as one by one the supposed bellwether differences between apes and humans, like toolmaking, fall away. Chimpanzees use leaves as seats, as it turns out; they fashion a kind of footwear to protect themselves from thorns; they ''fish'' for termites with twigs and reeds they strip and cut for the occasion.
But surely culture itself remains impregnable, a fortress where the superiority of human beings, steeped in teaching, learning, language, art and cuisine, still resides. Let Bonzo try to get a table at Elaine's.
Now along comes one of the world's most distinguished primatologists, intent on breaching this last bastion of anthropocentrism. A professor of primate behavior at Emory University and the director of the Living Links Center, de Waal draws on more than 30 years of his own research among captive monkeys, bonobos and other chimpanzees, as well as on studies of wild primates by colleagues around the world, to poke ''a maximum number of holes in the nature/culture divide.''
Culture -- behavior learned from others -- was long vaunted as inimitably human. But de Waal points out how tired this presumption is. Monkeys teach their siblings how to wash sweet potatoes in the ocean; chimpanzee mothers show their young how to use stones to crack nuts; apes learn to medicate themselves with herbs. In 1999, an international survey of wild chimpanzees published in Nature described 39 distinct behavior patterns. In other words, separate communities of chimpanzees, even in the same environment, develop different social customs.
''The question whether animals have culture is a bit like whether chickens can fly,'' de Waal writes. ''Compared