Nevertheless, the study of homosexual activity in diverse species may elucidate the evolutionary origins of such behavior. Researchers are now revealing, for example, that animals may engage in same-sex couplings to diffuse social tensions, to better protect their young or to maintain fecundity when opposite-sex partners are unavailable—or simply because it is fun. These observations suggest to some that bisexuality is a natural state among animals, perhaps Homo sapiens included, despite the sexual-orientation boundaries most people take for granted. “[In humans] the categories of gay and straight are socially constructed,” Anderson says.