Phylogenetic analyses of behavior support existence of culture among wild chimpanzees

Abstract

Culture has long been considered to be not only unique to humans, but also responsible for making us qualitatively different from all other forms of life. In recent years, however, researchers studying chimpanzees (Pan troglodytes) have challenged this idea. Natural populations of chimpanzees have been found to vary greatly in their behavior. Because many of these interpopulation differences cannot be readily explained by ecological factors, it has been argued that they result from social learning and, therefore, can be regarded as cultural variations. Recent studies showing social transmission in captive chimpanzee populations suggest that this hypothesis is plausible. However, the culture hypothesis has been questioned on the grounds that the behavioral variation may be explained at a proximate level by genetic differences between subspecies. Here we use cladistic analyses of the major cross-site behavioral data set to test the hypothesis that the behavioral differences among the best-documented chimpanzee populations are genetically determined. If behavioral diversity is primarily the product of genetic differences between subspecies, then population data should show less phylogenetic structure when data from a single subspecies (P. t. schweinfurthii) are compared with data from two subspecies (P. t. verus and P. t. schweinfurthii) analyzed together. Our findings are inconsistent with the hypothesis that the observed behavioral patterns of wild chimpanzee populations can be explained primarily by genetic differences between subspecies. Instead, our results support the suggestion that the behavioral patterns are the product of social learning and, therefore, can be considered cultural.social learning ͉ cultural transmission ͉ Pan troglodytes ͉ cladistics

Genetic and ‘cultural’ similarity in wild chimpanzees

“…codes were treated as missing values in our quantitative analyses. Our numerical coding system differs from that used in the study of Lycett et al [42,43], in that these authors did not distinguish between behavioural variants that were absent and those that were absent owing to an ecological reason.…”

Cultural Evolution: A Review of Theory, Findings and Controversies

“…Many species also exhibit cultural traditions, defined as group differences generated by social learning (Lycett et al 2007;Whiten et al 1999). Only humans, however, appear to possess cumulative cultural evolution, defined as the accumulation of beneficial modifications over successive generations (Dean et al 2014).…”

The effect of innovation and sex-specific migration on neutral cultural differentiation

“…The authors argued that these patterns could not be explained by differences in ecology, and hence concluded that at least some of these traits are likely to be culturally inherited. Considerable controversy has surrounded the problem of cultural transmission in chimpanzees, as some have argued that observed patterns could also be consistent with a genetic basis for behaviours (Laland & Janik 2006), while additional evidence has been presented based on cladistic analysis suggesting the behaviours are more likely to be culturally inherited (Lycett et al 2007(Lycett et al , 2010. As other research on chimpanzees has failed to find significant differences between patterns of variation among groups for genetic loci versus behavioural traits (Langergraber et al 2011), the extent to which these behaviours are culturally inherited remains unclear.…”