Third Gender - Biology

Biology

In animals that are gonochoristic, a number of individuals within a population will not differentiate sexually into bodies that are typically male or female; this is called intersexuality. The incidence varies from population to population, and also varies depending on how femaleness and maleness are understood. Biologist and gender theorist Anne Fausto-Sterling, in a 1993 article, argued that if people ought to be classified in sexes, at least five sexes, rather than two, would be needed.

Evolutionary biologist Joan Roughgarden argues that, in addition to male and female sexes (as defined by the production of small or large gametes), more than two genders exist in hundreds of animal species. Species with one female and two male genders include red deer who have two male morphs, one with antlers and one without, known as hummels or notts, as well as several species of fish such as plainfin midshipman fish and coho salmon. Species with one female and three male genders include bluegill sunfish, where four distinct size and color classes exhibit different social and reproductive behaviours, as well as the spotted European wrasse (Symphodus ocellatus), a cichlid (Oreochromis mossambicus) and a kind of tree lizard, Urosaurus ornatus. Species with two male and two female genders include the white-throated sparrow, in which male and female morphs are either white-striped or tan-striped. White-striped individuals are more aggressive and defend territory, while tan-striped individuals provide more parental care. Ninety percent of breeding pairs are between a tan striped and a white striped sparrow. Finally, the highest number of distinct male and female morphs or "genders" within a species is found in the side-blotched lizard, which has five altogether: orange-throated males, who are "ultra-dominant, high testosterone" controllers of multiple females; blue-throated males, who are less aggressive and guard only one female; yellow-throated males, who do not defend territories at all but cluster around the territories of orange males; orange-throated females, who lay many small eggs and are very territorial; and yellow-throated females, who lay fewer, larger eggs and are more tolerant of each other.