Chimpanzees have real cultures

Social behavioral differences indicate cultural learning

How often chimpanzees groom each other's fur is also a question of their culture. © Clara Dubois
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Because of typical human: even chimpanzees can develop social cultures. This is confirmed by observations of wild animals in a protected area in Zambia. They show that there are distinctive differences in social behavior between separated chimpanzee groups - differences that must be learned culturally. Because the genes or the environment can be excluded as an explanation for the behavioral differences, as the researchers report.

For a long time, culture in the sense of a trained social behavior was regarded as the domain of man. But scientists now suspect that other creatures can develop real cultures. Evidence of this they want to have found, among other things in our closest relatives, the chimpanzees. According to this, the great apes are capable of cultural activities - and sometimes even have behaviors reminiscent of religiously motivated human rituals.

Influence of genes and environment

But what is really true about these observations? As reported by Sarah DeTroy of the University of Leipzig and her colleagues, researchers in most cases compare groups of wild chimpanzees that live in different environments and have large genetic differences. Therefore, it can not be ruled out that supposedly culturally induced behavioral differences between groups actually go back to the genes or the environment.

In order to rule out the influence of such factors, the scientist and her team have now observed four chimpanzee groups in the Chimfunshi sanctuary in Zambia. The apes living there not only share the same habitat, there are no systematic genetic differences between them. "These conditions offer us a unique opportunity to study cultural differences in chimpanzees, " says DeTroy.

Sometimes more, sometimes less sociable

During the three-year study period, the researchers documented various aspects of the social behavior of the animals - how many individuals come together to form small groups within the large group, how close are the individual individuals on average and how often do they care for each other? It became apparent that there were indeed significant differences between the four separated groups in relation to these issues. display

The biggest difference was the size of the so-called subgroups - the number of individuals living closely together in everyday life. Thus, two of the groups formed significantly larger subgroups than the other two. "The most sociable groups were also social in the other aspects, " says senior author Daniel Haun. "The chimpanzees in these groups were on average average closer to each other and operated much more mutual grooming."

Learned socially

The deciding factor was that all these observed differences were stable over time and thus seemed to be characteristic for the respective chimpanzee group. This suggests, according to the scientists, that they could actually be the result of cultural learning.

"Although we did not directly study the origins of these differences in the study, we know that chimpanzees can learn from each other socially, and that primates can adapt their social behavior to their context. The individuals in each group may have observed patterns of interaction with other chimpanzees and learned them socially, "says Haun.

In the future, he and his colleagues want to investigate more closely the transmission of cultural "trends" among the chimpanzees: for example, how do differences in general sociability influence other behaviors, such as cooperation? (Proceedings of the National Academy of Sciences, 2018; doi: 10.1073 / pnas.1722614115)

(University of Leipzig, 21.11.2018 - DAL)