In the primate world, generally speaking, females will invest more time in the care of their offspring than males do (Sefcek, 1999).         However, in some primate species, like Titi monkeys (Callicebus) and Barbary macaques (Macaca); males will invest as much time and often times will invest more time in the care of offspring than females do. The motivation for male-infant interaction between these two species differs dramatically. Three hypotheses have been proposed to explain this behavior in these males; Hypothesis #1: Paternal Investment Hypothesis, Hypothesis #2: Mating Effort Hypothesis, and Hypothesis #3: Agonistic Buffering Hypothesis (Paul, 1996). Paternal Investment by male Titi monkeys can be explained the paternal investment hypothesis, whereas male parental investment by Barbary macaques is explained by the agonistic buffering hypothesis. Neither Titi males nor Barbary males invest time in their offspring under the mating effort hypothesis. Titi males invest time in their offspring to ensure that their monogamous female partner can recuperate after giving birth more quickly, thus making her more receptive and in turn shortening her interbirth interval (Whitten, 1982). In sharp contrast to Titi males, Barbary males will invest time in any offspring, which therefore allows the lower ranking male care-givers opportunities to build and strengthen their social alliances with the higher ranking males of the troop (Paul, 1996). This behavior is therefore political in it's nature and offers a form of protection for the male care-givers that invest time in the troop's offspring.