Let’s begin not with dreams but by going to the zoo. Penguins are monogamous. Females lay a large egg and then return to the sea to feed. The male incubates the egg for many weeks. When he is nearly dead from hunger and cold, the egg hatches and his mate returns. She regurgitates food to feed the fledgling while he goes to sea to feed. Many bird species are monogamous because the two sexes can share in bringing up the next generation.

Sixty years ago, one of the most consequential events of the past century occurred: the first sale of a drug called Enovid. At the time, it was illegal to use any form of contraception in Massachusetts, where Enovid was developed. But soon everyone just called Enovid the Pill.