The importance of males to the survival of infants is argued to be a major force in the evolution of male-female association in primates (van Schaik, 1996; Palombit et al., 1997; Sterck et al., 1997; Palombit, 1999). Across taxa, however, the extent and nature of males“ interactions with immatures, especially infants, vary enormously, from intense, directed caregiving in some NewWorld monkeys like marmoset, tamarins, and titis (Wright, 1984; Goldizen, 1987), to mere tolerance with occasional affiliation as in many Old World monkeys (Whitten, 1987; Maestripieri, 1998). Differences across and within species have been linked to various functions of males interactions with infants: while in some cases they represent investment by males in related infants, usually offspring (e.g. Busse and Hamilton, 1981; Anderson, 1992), in others, males appear to be using infants as social tools, either in their competitive interactions with other males (Paul et al., 1996), or as means to gain mating access to infants-mothers (Smuts, 1985; Ferrari, 1992; van Schaik & Paul, 1996). To add to the complexity, several functions might apply in the same species. In baboons, for example, all three have been invoked to explain male-infant interactions (Packer, 1980; Smuts & Gubernick, 1992).
In considering the function of male-immature relationships researchers have examined the benefits that immmature animals gain from their associations with males. It has been argued that, for most polygynous primates, the primary contribution that males make to their offspring's fitness is protection from predators and/or infanticide by unrelated adult males (Dunbar, 1984; van Schaik, 1996; Palombit, 1999; van Schaik & Janson, 2000).