The Chemistry Between Us: Love, Sex, and the Science of Attraction

by Larry Young

Evolutionary theorists have long questioned why we have longer penises than our primate cousins. One theory has it that men use them for a kind of Anthony Weiner–esque “look-at-me!” display—sort of like a lion’s mane: a symbol to other males that we are he-men to be reckoned with. Our ancestors with longer ones chased rival males away from females. Another theory suggests that longer penises evolved in men because our sperm compete with that of other males, who may mate with the same female just after us, inside the vaginal canal. The closer to the cervix we can make a deposit, the bigger head start we can give our swimmers in the great race to the egg. A third idea suggests that women are choosy. Unlike most female primates, women can orgasm more than once. When they figure out that the male penis is a handy device for inducing said orgasms, they select men who are generously equipped.