Why do males of so many species--such as the black-winged damselfly--have such complicated penises, complete with bristles and nobbles and spikes? Because the penis is not just for sperm delivery: it can also have other purposes, like persuading a promiscuous female to dump the sperm of her previous lover. And why do males fight all the time? Why do females of some species cannibalise their mates? Worse, what if you're ugly? What if you're poor? What if you're a wimp? What if you're a poor ugly wimp? All is not necessarily lost. Find out why...

This episode features interviews with penis specialist Alan Dixson of San Diego Zoo, cannibalism specialist Maydianne Andrade of the University of Toronto, and lizard king Barry Sinervo of UC Santa Cruz.

It includes the songs Pocket Rocket, about the evolution of penis shape, and the sexual cannibalism song (Hungry for Love).