Why marry a guy who gets down?

Reading (Diamond, 1992) p. 128 about the evolutionary biology rational for aging in humans and wondered about depression in men. Jared describes "optimization" as the explanation for why an obviously good trait, like longevity, wouldn't get as pronounced as physically possible. The answer is that whole organisms live or die, not just single traits, and the entire organism is a cooperating whole of multiple strategies each with cost-benefit aspects. Why, then, would depression exist at all? I believe dysfunctions like depression are runaway versions of functional features of an organism's makeup. Depression mitigates ego. It might, therefore, make a beta male more attractive to an alpha female by dampening his will to dominate her, making it possible for them to be cooperating mates instead of knocking the female out of the breeding game due to her unusually potent resentment of being dominated. A woman who fought back with enough determination to kill or cripple either herself or the offending male, or who was sufficiently repelled by the dominating behavior of males to run away and live in isolation from them, would eliminate herself from the gene pool. But a strong, male-resistant woman succeptible to a romantic approach by a less macho man would make a resourceful mother, especially with the support of an emotionally dependent mate. Evolutionary biology authors often talk about the role of year-round sex in keeping fathers at home to help raise their own children. Depressive tendancies might just as convincingly create an emotional dependence of the moody male on the more resilient female with a strong sense of family, assisting to keep him around. The benefits for her, and their offspring, would naturally depend on the extremity of the respective traits in play. But optimization for the organism may well have included a checkmark on the plus side for mild depression in the male, working in partnership with an emotionally robust female, especially since getting the blues does not preclude other desirable traits such as intelligence.

References

Diamond, J. (1992). The Third Chimpanzee. (1st ed.) New York: HarperCollins.