From the New York Times bestselling author of Upheaval, a fun and wide-ranging exploration of why human sexuality is so different from other animals’, and how it made us who we areTo us humans, the sex lives of animals seem weird. But it’s our own sex lives that are truly bizarre. We are the only social species to insist on carrying out sex privately. Stranger yet, we have sex at any time, even during periods of infertility, such as pregnancy or post-menopause. A human female doesn’t know her precise time of fertility and certainly doesn’t advertise it to human males by the striking color changes, smells, and sounds used by other female mammals.