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 ...

All animals need sleep. When humans or animals don't get enough, it can lead to trouble paying attention, irritability, and other ill effects. And yet, researchers reporting in the journal Current ...

When it comes to animals romancing in the wild, things get weird—really weird. Some animals offer bizarre gifts, some put on daring dances, and others? Well, let’s just say things get really messy.

Last year, the New York Times (Mooallem, 03.29.10), published an article entitled "Can animals be gay?" which discussed biologists' recent and past discoveries of same-sex animal behavior, how ...