for something desirable. In olive baboons, Papio anubis, it has been found that individuals perform altruistic behaviors as a form of trade in which a behavior is provided in exchange for benefits, such as reduced aggression. The grooming was evenly balanced across multiple bouts rather than single bouts, suggesting that females are not constrained to complete exchanges with single transactions and use social grooming to solidify long-term relationships with those in their social group. In addition, white-handed gibbon (Hylobates lar) males were more attentive to social grooming during estrus of the females in their group. Though the behavior of social grooming itself was not beneficial to the one providing the service, the opportunity to mate and subsequent fertilization increases the reproductive fitness of those participating in the behavior. This study was also successful in finding that social grooming performance cycled with that of the females ovarian cycle. Ontogeny of social grooming General learning and reciprocation of allogrooming In most cases, allogrooming is an action that is learned from an individual's mother. Infants are groomed by their mothers and mimic these actions on each other and the mother as juveniles. This action is reciprocated on other group members (non-mother or of a different rank) more often once the individual is a fully developed adult and can follow normal grooming patterns. Sex based differences in learning Male and female members of a species may differ in learning how, when and whom to groom. In stump-tailed macaques, infant females mimic their mothers' actions by grooming their mothers more often than their males counterparts do and by grooming the same group members that their mothers groom. This mimicry is suggested to indicate identification-based observational learning in infant stump-tailed macaques, and the daughters' penchants for maternal mimicry and kin-biased grooming versus the sons' penchants for rank-biased grooming falls in line with their social roles in groups, where adult males require alliances in order to gain and maintain rank. Tool usage In nearly all instances of social grooming, individuals use their own body parts, such as hands, teeth or tongue, to groom a group member or infant. It is very rare to observe instances of tool usage in social grooming in non-human animals; however, a few such instances have been observed in primates. In a 1981 observational study of Japanese macaques at Bucknell University, a mother macaque was seen to choose a stone after observing several