Men have nipples, mammary glands and the hormones required, but the ability for male lactation rarely turns on. Here’s why ...

When closely related species mate, their offspring sometimes survive but cannot reproduce. This pattern often affects males ...

Birds do it, and bees do it. Indeed, researchers estimate that over 99.9% of eukaryotes reproduce sexually. What, then, are the true costs and benefits of sex? Yet again, this simple example ...

Most people know only two things about the appendix: You don’t need it – and if it bursts, you need surgery fast. That basic ...