Cultures in chimpanzees

As an increasing number of field studies of chimpanzees (Pan troglodytes) h ave achieved long-term status across Africa, differences in the behavioural repertoires described have become apparent that suggest there is significa nt cultural variation(1-7). Here we present a systematic synthesis of this information from the seven most long-term studies, which together have accu mulated 151 years of chimpanzee observation. This comprehensive analysis re veals patterns of variation that are far more extensive than have previousl y been documented for any animal species except humans(8-11). We find that 39 different behaviour patterns, including tool usage, grooming and courtsh ip behaviours, are customary or habitual in some communities but are absent in others where ecological explanations have been discounted. Among mammal ian and avian species, cultural variation has previously been identified on ly for single behaviour patterns, such as the local dialects of song-birds( 12,13). The extensive, multiple variations now documented for chimpanzees a re thus without parallel. Moreover, the combined repertoire of these behavi our patterns in each chimpanzee community is itself highly distinctive, a p henomenon characteristic of human cultures(14) but previously unrecognised in non-human species.