You'll find much of the relevant evolutionary biology and game theory described in two intriguing recent books, Matt Ridley's The Red Queen and Robert Wright's The Moral Animal. Reproduction costs them little, and Darwinian selection favors fecundity. To be sure, males pursue most avidly those females whose appearance telegraphs fertility. But if nothing else mattered, males would proposition every plausible reproductive vessel in sight. More than a few males on the Potomac behave accordingly.
Females compete equally intensely for males, but emphasize quality over quantity.
They have to, because they invest more in each child, and cannot produce as many successful males. So females vie for the mate most likely to father and help raise premium offspring. One good predictor is the father's own record of success. In species that live communally, the female is thus programmed to prefer the high-status male. Like a pre-approved credit card, he is already certified to be healthy, wealthy and wise.