"The Rise and Fall of Sexual Promiscuity"

Interesting article from Forbes:

The study highlights several current theories of pair-bonding: instead of fighting, male hominids began to devote effort to caring for offspring, protecting their mate, or provisioning food for sex. But Gavrilets builds mathematical models to show how each of these hypotheticals leads to a “sub-optimal” outcome—how “investing more in offspring means that there is more paternity for other males to steal.” Run the model, and instead of choosing cooperation, the males will choose to fight. It’s not the outcome any one male desires, but the free-rider problem effectively “traps” the whole group in a benighted state.

Gavrilets proposes a modification to existing theory. What if we assume that males began to provide for one—and only one—female, and females, likewise, began to depend on a sole mate for food and help with childcare? First, not all men are created equal; there are few Ryan Goslings and many Kevin Redmons. The weaker among us quickly learned the futility of direct competition, and turned to “alternative reproductive strategies” to spread our genes. (I may not be a dreamboat, baby, but I’ll bring you coffee in bed.) Second, females make choices. Whereas previous models ascribe females a passive role, Gavrilets asserts that “because they receive direct benefits from provisioning males, females should be choosy, and they may become, to some extent, faithful” to their providers.

Promiscuity is a funny thing in nature. Despite what your mother and youth pastor spent so many years telling you, sleeping around has real (genetic) benefits. Polyandry—in which females take more than one mate—allows for better gene diversity, boots the likelihood of fertilization, decreases infanticide, and means more male providers. Gavrilets acknowledges that in switching from promiscuity to monogamy, females actually risked lower fertility. The tradeoff was security.

When he runs the model again, with these two assumptions in place, the outcome is different: instead of a spiral into violent competition, male provisioning and female faithfulness “co-evolve in a self-reinforcing manner.” Males escape the “social dilemma” and pair-bonding replaces promiscuity.

The issue is: If promiscuity among females were to increase, would it eventually cause an increase in "violent competition" among men? Anecdotal evidence would suggest it does (e.g., bar fights over women).