Bruce Bagemihl writes that the presence of same-sex sexual behavior was not officially observed on a large scale until the s due to possible observer bias caused by social attitudes towards LGBT people, which made homosexuality in animals a taboo subject. Oxford University Press. Olympic marmot left and Hoary marmot right. The origin of that beautiful neck has also been attributed to sexual selection. Retrieved 16 June For these mammals, there is documented evidence of homosexual behavior of one or more of the following kinds: Jonathanthe world's oldest tortoise an Aldabra giant tortoisehad been mating with another tortoise named Frederica since
As with so many areas of science, there has been a historical skew toward understanding male behavior.
NCSilverBear Positively uplifting. Hochuli; 22 March "Traumatic insemination in the plant bug genus Coridromius Signoret Heteroptera: When taken from their mate and placed in a cage with the hen, the two would commence to fight, ferociously as if to the death, drawing blood, feathers flying. Researchers found that disabling the fucose mutarotase FucM gene in laboratory mice — which influences the levels of estrogen to which the brain is exposed — caused the female mice to behave as if they were male as they grew up.
American Journal of Primatology.