The motivations for and implications of these behaviors have yet to be fully understood, since most species have yet to be fully studied.
In most instances, it is presumed that the homosexual behavior is but part of the animal's overall sexual behavioral repertoire, making the animal "bisexual" rather than "homosexual" as the terms are commonly understood in humans, A majority of the research available concerning homosexual behavior in animals lacks specification between animals that exclusively exhibit same-sex tendencies and those that participate in heterosexual and homosexual mating activities interchangeably.
This lack of distinction has led to differing opinions and conflicting interpretations of collected data amongst scientists and researchers.
While studies have demonstrated homosexual behavior in a number of species, Petter Bøckman, the scientific advisor of the exhibition Against Nature?
in 2007, speculated that the true extent of the phenomenon may be much larger than was then recognized: No species has been found in which homosexual behaviour has not been shown to exist, with the exception of species that never have sex at all, such as sea urchins and aphis.
Moreover, a part of the animal kingdom is hermaphroditic, truly bisexual. Some researchers believe this behavior to have its origin in male social organization and social dominance, similar to the dominance traits shown in prison sexuality.
Others, particularly Bagemihl, Joan Roughgarden, Thierry Lodé and Paul Vasey suggest the social function of sex (both homosexual and heterosexual) is not necessarily connected to dominance, but serves to strengthen alliances and social ties within a flock.Research indicates that various forms of this are found in every major geographic region and every major animal group.According to Bruce 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".For instance, homosexuality in animals was cited by the American Psychiatric Association and other groups in their amici curiae brief to the United States Supreme Court in Lawrence v.Texas, which ultimately struck down the sodomy laws of 14 states.We identified a cell group within the medial preoptic area/anterior hypothalamus of age-matched adult sheep that was significantly larger in adult rams than in ewes...