Male care in primates: does it ever reflect paternity?

Female mammals have internal fertilization, long gestation, and lactation. These basic facts of reproductive biology have important social consequences. Internal fertilization (accompanied by sperm competition) forces males either to face considerable uncertainty about paternity or to invest heavily in mate guarding. Long gestation increases the benefits of mate desertion for males. And because only females lactate, males have relatively less to contribute to rearing the young. Hence, it is not surprising that male mammals rarely assist their mates in caring for their young: Direct infant care by males occurs in fewer than 5 percent of all mammalian species. 1,2 In fact, many mammalian mothers attack males, even possible father of their offspring. 3