(Deutsches Primatenzentrum (DPZ)/German Primate Center) Humans and monkeys are social beings and benefit from a community. But the closeness to conspecifics is an opportunity for parasites to infect new hosts. Clémence Poirotte from the German Primate Center investigated how mandrills recognize conspecifics infected with intestinal parasites. The monkeys are able to smell an infected group member and groom them less than healthy individuals. This component of the 'behavioral immune system' plays a crucial role in the co-evolution of host and parasite.