You’ve just got a case of SINBAD: Single Income, No Babe, Absolutely Desperate. - Olivia Judson

If a proclivity for promiscuity is genetic, then yes, promiscuous behavior will become more common if loose females tend to have more children than their monogamous peers. That’s how natural selection works.

Evolution does not obey human notions of morality, nor is human morality a reflection of some natural law. The deadly sins would be different if they mirrored evolutionary no-no’s. Lust, for one, would be deemed a virtue; chastity would be deplored.

The battle of the sexes is no myth. Success at sexual reproduction is at the heart of the evolutionary process. But greater success for her often means less success for him. The upshot? An eternal war—and an astounding diversity of strategies.