Monkeys constantly observe and evaluate their social environment. It stands to reason that the social and mental abilities required to do so were favored by evolution. After all, these abilities should influence how an animal interacts with its conspecifics and, as a result, what social position it can attain within the group's hierarchy. Researchers from the DPZ and the University of Göttingen have now investigated whether this widely held assumption is correct by studying 46 wild male Assamese macaques in Thailand. The paper is published in the journal Current Biology.