Homosexual behavior in animalsとは 意味・読み方・使い方

Homosexual behavior in animals refers to the documented evidence of homosexual and bisexual behavior in animals. This article covers non-human species, for homosexuality in humans, see Homosexuality. Such behaviors include sex, courtship, affection, pair bonding, and parenting among same sex animals. A 1999 review by researcher Bruce Bagemihl shows that homosexual behavior has been observed in close to 1,500 species, ranging from primates to gut worms, and is well documented for 500 of them. Animal sexual behavior takes many different forms, even within the same species. The motivations for and implications of these behaviors have yet to be fully understood, since most species have yet to be fully studied. According to Bagemihl, "the animal kingdom [does] it with much greater sexual diversity — including homosexual, bisexual and nonreproductive sex — than the scientific community and society at large have previously been willing to accept." Current research indicates that various forms of same-sex sexual behavior are found throughout the animal kingdom. A new review made in 2009 of existing research showed that same-sex behavior is a nearly universal phenomenon in the animal kingdom, common across species. Homosexual behavior is best known from social species. According to geneticist Simon Levay in 1996, "Although homosexual behavior is very common in the animal world, it seems to be very uncommon that individual animals have a long-lasting predisposition to engage in such behavior to the exclusion of heterosexual activities. Thus, a homosexual orientation, if one can speak of such thing in animals, seems to be a rarity. One species in which exclusive homosexual orientation occurs, however, is that of domesticated sheep (Ovis aries). "About 10% of rams (males) refuse to mate with ewes (females) but do readily mate with other rams."