Monkeys give in to peer pressure.
A nine-year study conducted on Vervet monkeys has revealed that social traditions are transferred through different communities of animals.
Boffins from the University of Lausanne in Switzerland and Paul Sabatier University in France say that male monkeys who join more sociable communities must adapt quickly to match the social styles of the group.
Almost 250 Vervet monkeys in South Africa were studied and the experts found that those from the Ankhase (AK) community were more likely to return the favour if they were groomed by other monkeys.
The study's lead author Elena Kerjean said: "We found that individuals in one group - AK - display significantly more affiliative behaviours than in the two other groups, and this difference was stable over nine years of study."