Chimps may put their own spin on culture.

Chimpanzees don't read or watch television, have no interest in sending their kids to school, and show no inclination for religious worship. Still, a range of evidence suggests that these group-living primates devise their own cultural traditions, according to a new synthesis of field and laboratory studies.

The analysis, published in the December Current Anthropology, clashes with the traditional view that attributes culture--a tricky concept to define and study--to humans alone. A minority of investigators has long promoted the idea that chimps and other nonhuman primates, and even whales (SN: 11/28/98, p. 342), invent useful new behaviors and pass them on to kin and fellow group members, a sign of basic cultural capacities.

"A comparison of chimpanzee and human cultures shows many deep similarities, suggesting that they share evolutionary roots," contend Christophe Boesch and Michael Tomasello, both anthropologists at the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany.

Unlike chimps, however, people pass on knowledge by talking to one another and often assume that others' behaviors are motivated by intentions. These social skills allow humans to modify cultural innovations more quickly and in more varied ways than chimps do, as well as to spread advances over large areas, Boesch and Tomasello hold.

The two researchers note that up to now they have been "somewhat at odds" over the question of chimp culture. Boesch had asserted that chimp populations pass along cultural traditions of tool use and communication signals; Tomasello had countered that individual chimps living together may independently invent the same useful behavior, such as using a rock to crack nuts.

Current evidence on the daily practices of wild chimps contains many gaps, but it allows for a tentative consensus, the researchers say. They reviewed extensive published material on tool use and other behaviors among African chimp populations in four wildlife areas: Bossou, Gombe, Mahale, and Tai.

Boesch and Tomasello assume that culture involves a set of social learning mechanisms that are used to transmit knowledge to particular individuals. Both chimps and humans exhibit socially learned patterns of activities that last from one generation to the next, they say.

Social influences promote population-specific styles of the same chimp behaviors, the scientists argue. For instance, Tai chimps eat ants by holding a stick with one hand and dipping it among soldier ants guarding their nest entrance. As ants climb the stick, the apes withdraw the tool; with a hand twist, they sweep off insects with their lips.

Gombe chimps also use one hand to place a stick among the same species of soldier ants. But after withdrawing an ant-laden probe, they sweep it through the closed fingers of the free hand and then shove the mass of insects into their mouths. Combined with the use of a longer stick, this procedure more efficiently gathers ants than the one observed at Tai, Boesch and Tomasello say.

"Ant dipping" and other cultural acts arise through emulation, in which an individual observes a behavior and learns how to use it to achieve specific goals, they assert. It's less clear whether chimps ever understand the intended results of another's behavior.

Boesch also reports examples of teaching among Tai chimps. Some mothers leave nuts and stone "hammers" in position near anvils for their infants to use. One mother demonstrated a slowed-down version of nut cracking for her child, and another mother modified her son's positioning of a nut for cracking.

The debate continues. Psychologist Bennett G. Galef Jr. of McMaster University in Hamilton, Ontario, remains unconvinced that chimps teach or accumulate cultural knowledge. But anthropologist William C. McGrew of Miami University in Oxford, Ohio, says that field studies beyond those in the new report demonstrate cultural capacities of not only chimps but macaque monkeys, too.