Paternal kin discrimination in wild baboons

Mammals commonly avoid mating with maternal kin, probably as a result of se lection for inbreeding avoidance. Mating with paternal kin should be select ed against for the same reason. However; identifying paternal kin may be mo re difficult than identifying maternal kin in species where the mother mate s with more than one male. Selection should nonetheless favour a mechanism of paternal kin recognition that allows the same level of discrimination am ong paternal as among maternal kin, but the hypothesis that paternal kin av oid each other as mates is largely untested in large mammals such as primat es. Here I report that among wild baboons, Papio cynocephalus, paternal sib lings exhibited lower levels of affiliative and sexual behaviour during sex ual consortships than non-kin, although paternal siblings were not signific antly less likely to consort than non-kin. I also examined age proximity as a possible social cue of paternal relatedness, because age cohorts are lik ely to be paternal sibships. Pairs born within two years of each other were less likely to engage in sexual consortships than pairs born at greater in tervals, and were less affiliative and sexual when they did consort. Age pr oximity may thus be an important social cue for paternal relatedness, and p henotype matching based on shared paternal traits may play a role as well.