BIRDS DO IT, dolphins do it—even fruit flies do it. It’s the phenomenon of same-sex partnering, and a new review of existing research finds that it occurs nearly universally throughout the natural world. But that doesn’t mean that all same-sex behaviors are the same—or serve the same purpose. Male fruit flies that court other males, for example, do so because they lack a gene that allows them to tell the difference between sexes, says study author Nathan Bailey of the University of California–Riverside. Female Laysan albatrosses, in contrast, partner to raise young when males are scarce. The lesson, says Bailey, is that “same-sex sexual behavior can be found in a wide variety of species in nature, but to really advance the topic scientifically and for the popular press, it is important to think about the evolutionary origins of the behavior and how they vary across species.” —Hannah Schardt