No, Dr. Bill Cosby (of Cliff Huxtable fame), I'm not trying to plagiarize the title of your book. Rather, I'm talking about an article published online today in PNAS by Charpentier and colleagues about paternal care in yellow baboons (Papio cynocephalus). I'm no expert on primate behavior (even though when I GSIed Primate Social Behavior last semester I read a billion student papers, many of which were about various forms of baboondom), so I won't get too in depth here. The interesting finding of the authors' study was that paternal investment in this species (or subspecies of P. hamadryas, if you lump like me) can have a "non-trivial" (to quote a famous primatologist) effect on offspring's reproductive success. Paternal presence in the offsprings' social group tends to cause offspring to mature faster, though only if the father was of high rank for male offspring. Faster maturation means one can begin his/her reproductive career earlier, potentially increasing reproductive success.
Paternal care is, arguably, a normal thing in modern human life, so it might be surprising to some that the behavior is relatively rare in the mammal world. But in many mammal, viz. primate societies, there are lots of reasons why it may make more sense for males not to invest in parenting. For starters, males have countless sperm, which are produced throughout their mature lifetime, whereas females are born with a set amount of eggs: gametically, males are millionaires, but females more penurious. On top of that, females bear the burden of pregnancy and nursing, which are very resource-draining. So females have more to lose from negligent parenting than males. Furthermore, in many primate societies, especially polygamous ones, it can be near-impossible for males to be certain of their paternity--why care for an infant that might belong to someone else? Plus, time spent taking care of one potential offspring is time that could be possibly better spent trying to sire a new one. Thus, in the primate world, paternal care is a fairly rare behavior, though the authors note that when there is paternal care, the species tend to be 'monogamous.'
Yellow baboons are not monogamous, and they live societies with many mature males and females. But these baboons are fairly adept at knowing which offspring are theirs, and males often behave in ways beneficial to their offspring, through protection from both agonistic interactions and infanticidal males, and by helping forage. The authors show that such paternal behavior helps offspring reach sexual maturity earlier (hybird females also tend to mature faster, possibly a heterotic phenotype...?)
In some episode of The Simpsons whose details I forget, Lisa Simpson berates her father, calling him, "Baboon, baboon, baboon!" But perhaps this such a slur was not so slanderous. Perhaps his involvement in parenting (or his coresidency in the polygynandrous town of Springfield) will in some way bolster her reproductive success (though not in earlier maturity). Indeed, it would be interesting to determine exactly what role parental care played in human origins. Lovejoy posited that it was the watershed event that led to the emergence of hominins--something about females dropping so many babies ("Hey, wha' happen?!"). . . . While the Charpentier et al. study suggests that the behavior could well have been a good paternal reproductive strategy, I don't know that the idea is easily testable.
Charpentier MJE, van Horn RC, Altmann J, Alberts SC. 2008. Paternal effects on offspring fitness in a multimale primate society. Proc Nat Acad Sci 105: 1988-1992.
Lovejoy CO. 1981. The origin of man. Science 211: 341-350.