We're All Mammals part III

Mammals

Mammals (class Mammalia) are a clade of warm-blooded amniotes. Among the features that distinguish them from the other amniotes, the reptiles and the birds, are hair, three middle ear bones, mammary glands in females, and a neocortex (a region of the brain). The mammalian brain regulates body temperature and the circulatory system, including the four-chambered heart. The mammals include the largest animals on the planet, the rorqual whales, as well as the most intelligent such as elephants as well as some primates and cetaceans. The basic body type is a four-legged land-borne animal, but some mammals are adapted for life at sea, in the air, in the trees, or on two legs. The largest group of mammals, the placentals, have a placenta which feeds the offspring during pregnancy. Mammals range in size from the 30–40 millimeter (1- to 1.5-inch) bumblebee bat to the 33-meter (108-foot) blue whale.

The word "mammal" is modern, from the scientific name Mammalia coined by 
Carl Linnaeus in 1758, derived from the Latin mamma ("teat, pap"). All female mammals nurse their young with milk, which is secreted from special glands, the mammary glands. According to Mammal Species of the World, 5,702 species were known in 2005. These were grouped in 1,229 genera, 153 families and 29 orders. In 2008 the IUCN completed a five-year, 17,000-scientist Global Mammal Assessment for its IUCN Red List, which counted 5,488 accepted species at the end of that period. In some classifications, the mammals are divided into two subclasses (not counting fossils): the Prototheria (order of Monotremata) and the Theria, the latter composed of the infraclasses Metatheria and Eutheria. The marsupials comprise the crown group of the Metatheria and therefore include all living metatherians as well as many extinct ones; the placentals likewise constitute the crown group of the Eutheria.

Homosexual behavior in animals

Homosexual behavior in animals refers to the documented evidence of homosexual and bisexual behavior in various (non-human) species. Such behaviors include sex, courtship, affection, pair bonding, and parenting among same-sex animal pairings. 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 behaviour 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."

More at WikiPedia: http://en.wikipedia.org/wiki/Homosexual_behavior_in_animals

So, homosexuality is 100% all-natural!
But I've known THAT for years!