"It was once thought that women have orgasms so the muscle contractions could shepherd sperm toward the cervix, what Barash calls, alarmingly, “the uterine suck-up theory.” But this has been more or less proven false.
Shlain believes orgasm is a reward to women, a little something to entice them to have sex rather than focus on the prospect of death in childbirth. “Once she knows death is associated with sex, she needs to have an impetus to keep having her do it,” he says." -
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It's interesting, men have an obvious ... payload. The process feels great. Women, many complain they don't even know what an orgasm feels like. Some argue that a female orgasm doesn't feel at all like what a man feels, though such a thing would be almost impossible to prove, it'd have to be based on description more than anything. The idea that sexual intercourse feels good for no other reason than to perpetuate its commission is not new. And of course if sex didn't feel good, would we still do it? Would we intellectually reason that by not doing it, regardless of how it felt, we'd die out as a species? I think the answer lies in understanding how the body works.
We must also understand that sex for pleasure vs sex for procreation though not the same thing, is not necessarily two sides to a coin. It's natural for people to practice having sex so that the chances of successful procreation may be increased. True, virgin couples are reported to get pregnant first time out. But normally, males and females during puberty experiment with sexual acts in an attempt to understand their bodies, to practice for the eventual mating, and to experience this new, joyous feeling. It's not far fetched to then further correlate the importance of procreation and the family unit to love, then to love making. From there, one can easily see that love making between two same-sex partners becomes a sole expression, rather than practice for procreation.
It's all still natural. Two gay men or women having sex to express love, to bond, and to establish their pathways of intimacy may do so because they too wish to formulate a strong unit. Procreation and genes are all about perpetuation. Being high order intelligence-based lifeforms, it should not be a stretch to imagine how in some people, passing on a gene legacy may be less important than passing on a familial legacy (adoption, etc.)
In other words, we should not look at homosexuality as threatening our species (which would be the only reason to consider it against natural order). An interesting but highly difficult thing to prove: perhaps homosexuality is natural in more than just endorsing the same expression of bonding that all humans hetero and homo express alike... perhaps it's to keep population growth in check! Perhaps... I mean some species of frogs change gender to increase procreation if the population is threatened. Is it not possible that the biological groundwork for the opposite could exist?
My wife, a lesbian, once said: "IF God didn't want chicks to have sex, he wouldn't have made it so HOT."
The biological explanation of sexual intercourse is one thing. The biological explanation of arousal is something else. Reacting to arousal, is a choice. And so long as it is not detrimental to the parties involved, should be considered natural by default, regardless of the gender of the participants.