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charon [soylentnews.org] writes:

Researchers from the CNRS have discovered that mandrills use their sense of smell to avoid contamination [www2.cnrs.fr] by intestinal protozoans through contact with infected members of their group. Their work, published in Science Advances on 7 April 2017, shows that parasites shape the social behavior of these primates, leading them to develop a strategy of parasite avoidance through smell.

The Mandrillus Project was launched in 2012, in southern Gabon, to study the ecology of the world's sole population of wild mandrills habituated to human presence. Frequent grooming among these mandrills is undoubtedly a means of eliminating ectoparasites¹, but it also plays a major role in social cohesion—helping to soothe tensions after conflict, for example.

Mustering data from five years of field observation, the researchers demonstrated that mandrills harboring parasitic protozoans in their digestive tracts were less frequently groomed by their conspecifics than were healthy mandrills. Groomers especially avoided the perianal zone, which poses a high risk of contagion.

To pursue their investigations, the scientists conducted an experiment using antiparasitics. They captured infected mandrills, administered the antiparasitic drug, and returned the treated mandrills to their group. Now free of parasites, these primates once again enjoyed frequent grooming.

¹ An ectoparasite is an external parasite—that is, one that lives on the surface of a living being.

Original Submission