ARE differences in chimp behaviour down to culture or genetics? Some groups of chimps use twigs to fish for termites, others don’t. Some groups communicate by knuckle-knocking, others by slapping. While the accepted wisdom is that these are purely cultural differences, now it seems that genes may be involved too.

A team of primatologists headed by Kevin Langergraber of the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany, pulled together behavioural data on nine wild chimpanzee groups, and analysed DNA samples from 246 individual apes. Groups that were more genetically different turned out to have significantly more differences in their behaviours (Proceedings of the Royal Society B, DOI: 10.1098/rspb.2010.1112).

While there is no suggestion that behaviour is determined directly by genes – there is no gene for termite fishing – genetics might change behaviour indirectly, by influencing manual dexterity or some aspects of intelligence, for example. “We can’t rule out the genetic explanation,” says Langergraber.

“Genetic influences on chimp behaviour have always been a serious possibility that researchers maybe overlooked,” says Frans de Waal of Emory University in Atlanta, Georgia.


Fish culture

That’s not to deny the existence of animal culture, says de Waal. Evidence for cultural behaviour is overwhelming, even in supposedly primitive creatures such as fish. “Some people who don’t like the idea will pick this up,” he says, “but I don’t think they have a leg to stand on.”

In fact Langergraber’s work shows that while genetics may be involved in behaviour, it can’t be the dominant factor, according to Andrew Whiten of the University of St Andrews, UK. “If you look at the data, genetics explains a quarter of the variation at most.”

To firmly establish a genetic component, researchers need more detailed data. Ideally, they would be able to watch genetically diverse individuals exposed to similar behaviours, to see who picks up which behaviours.

That could be difficult in chimpanzees, whose groups are often separated by impassable features like mountain ranges, so they don’t meet and are equally distinct genetically and culturally, says Carel van Schaik of the University of Zurich, Switzerland. He thinks it might be easier in orang-utans, which have a more fine-grained distribution.

Or experiments may be the answer, according to Corsin Müller of the University of Vienna, Austria, who showed that mongooses have cultural traditions. When he introduced them to a new food item, he found that different groups developed their own methods of opening it.

When first posted, this article incorrectly gave Corsin Müller’s institution as the University of Zurich.