Chimpanzees may not have literature and ballet, but some researchers suspect that our close primate kin do have cultural traditions for behaviors such as tool use and grooming. Now a study provides the strongest evidence yet that chimps can learn traditions of tool use by observation. The authors say their work also reveals another trait previously seen only in humans: a tendency to conform to community standards.
Primatologists have catalogued dozens of behavioral differences among wild chimp populations. Chimps in one forest may use a certain technique to catch ants with a stick, for example, while a population in another forest uses another technique (Science, 25 June 1999, p. 2070). But critics have argued that to qualify as cultural traditions, such habits must be learned from fellow chimps--and that's been difficult to demonstrate in the wild, says Andrew Whiten at the University of St. Andrews in Fife, U.K.
Whiten and colleagues turned instead to two groups of captive chimps at Yerkes National Primate Research Center in Atlanta, Georgia. They selected a high-ranking female from each of two groups of 16 Yerkes chimps and gave them private lessons on using a stick to obtain food from a specially designed dispenser. One female learned a 'poke' technique, the other learned a 'lift' technique. Back in their respective groups, each female's peers took notice of how she worked the dispenser, and the vast majority adopted her technique, the team reports online 21 August in Nature. Even when some of the chimps independently discovered a better method, they tended to stick with what the rest of the group was doing. This suggests they were eager to conform, says Whiten.
Some chimp culture skeptics have been convinced, saying the study provides strong evidence that chimps have traditions they learn by observation. "I've been looking for this for 10 years," says Bennett Galef an animal behaviorist at McMaster University in Hamilton, Canada. Galef and others are less compelled by the claims regarding the chimps' conformist tendencies, however. Carel van Schaik, a biological anthropologist at the University of Zürich in Switzerland points out that chimps observe their group's favored technique more frequently, so their behavior could reflect what they've seen rather than a tendency to conform.