Evaluation Summary:
This article is of potential interest to researchers working on primate social behaviour, as it presents a novel mechanism for how an association with non-relatives can be favoured under kin selection. In a wild mandrill population, mothers are observed to preferentially lead offspring to associate with paternal half-sibs, a potential mechanism for encouraging nepotistic interactions between their offspring and other members of their group. The authors' explanation for their results was considered to be only partially supported by the data and a more measured and nuanced presentation would be appropriate.
(This preprint has been reviewed by eLife. We include the public reviews from the reviewers here; the authors also receive private feedback with suggested changes to the manuscript. Reviewer #3 agreed to share their name with the authors.)