Exchange of Grooming for Allomothering in Female Patas Monkeys

The question is asked whether grooming is exchanged for allomothering in patas monkeys (Erythrocebus patas). Six adult females in one group were observed during the non-birth season (no infants) and the birth season when three females had given birth to an infant. During the non-birth season the exchange of grooming and soliciting for it indicated reciprocity between non-kin. During the birth season, however, non-mothers groomed mothers much more than vice versa, and soliciting was shown more by mothers. This is in accord with the hypothesis that grooming is offered in order to be permitted to allomother. In addition, allomothering was often preceded and followed by grooming. Investment and reciprocity by unaffiliated (rarely grooming) non-kin females tended to occur most promptly. This is in accord with the hypothesis that fairness of reciprocity can be easier assessed if reciprocal acts occur immediately. Effects were less in affiliated non-kin pairs (frequently grooming), and least between kin.