Sexuality and gender are often at the forefront of cultural and political debate today. In his new book, The Sexual Evolution: How 500 Million Years of Sex, Gender, and Mating Shape Modern ...

In the animal kingdom, penises can be spiked, split, corkscrewed—even detachable. They're one of the most diverse structures in biology. The human penis is so uniform, it's an anatomical outlier.

Michelle Spear does not work for, consult, own shares in or receive funding from any company or organization that would benefit from this article, and has disclosed no relevant affiliations beyond ...