Résumé
Social animals are particularly exposed to infectious diseases.
Pathogen-driven selection pressure has thus favoured the evolution of
behavioural adaptations to decrease transmission risk, such as “social
distancing”. Yet, such strategy might deprive individuals from valuable
social interactions, generating a cost-benefit trade-off between pathogen
avoidance and social opportunities. Recent studies revealed that hosts
differ in the expression of these behavioural defences but the
determinants driving such inter-individual variation remain poorly
understood. Using 5 years of detailed behavioural and parasite data
obtained on a large natural population of non-human primates, we show
that, during grooming interactions, some female mandrills (Mandrillus
sphinx) consistently avoid their conspecifics’ peri-anal region, where
oro-faecally transmitted gastro-intestinal parasites accumulate, while
others do not. This hygienic trait is further highly repeatable across the
years and hygienic females are less parasitized on average than
non-hygienic females. While age, dominance rank and sociality level do not
influence hygienic tendencies, close maternal kin exhibit similar levels
of hygiene suggesting social inheritance from mothers to daughters. Our
study thus emphasizes that social inheritance of hygienic tendencies may
structure behavioural resistance to pathogens in host populations, with
unforeseen consequences on the dynamics of infectious diseases.