Pickup artists among the great tits (a species of bird, ok?) know how to get chicks: They sing at low frequencies just before females of their species begin laying eggs. It's a great technique! Unless they happen to be hanging out near sources of noise pollution, like highways, which force the tits to change their tune to a higher pitch so that the girls can hear their song in the first place.
But that's when things start going wrong. Although female tits will respond to higher songs if they can't hear the lower ones, males competing with noise pollution open up an opportunity for interlopers to swoop in later with their low-pitched songs and fertilize a female's eggs at the last minute. Sometimes this brand of avian infidelity leads to males raising chicks that aren't their own. But you can't pin this one on the ladies. They don't know those high-voiced boys are just trying to edge in any way they can, so they want to hedge their reproductive bets with a couple of gravelly-voiced men.
So males who adapt to circumstances lose out to males who just keep on being super-macho regardless. There’s probably an unflattering parallel to human behavior to be drawn here, but we’ll stick with the moral “highways eff everything up.”
