I understand that there are nerve evendings in the anus and the prostate for men and the back of the vagina for women but my question is WHY are there pleasure sensors in this part of the body? I mean I understand why penile/vaginal sex feels good. Its to provide an incentive for us to engage in this energy expensive behavior in order to reproduce but what’s the evolutionary advantage for anal sex? Is this evidence that nature wanted to give gay men something to look forward to?
The fact that there are nerve endings there has nothing to do with anal sex, but with defecation. Defecation is usually pleasurable; we’re all familiar with the sense of relief after relieving ourselves.
Mark Twain is often credited with remarking something to the effect that, “Of all life’s pleasures, copulation is the most over-rated, and defecation the most under-rated.”
The fact that there are nerve endings there has nothing to do with anal sex, but with defecation. Defecation is usually pleasurable; we’re all familiar with the sense of relief after relieving ourselves.
Mark Twain is often credited with remarking something to the effect that, “Of all life’s pleasures, copulation is the most over-rated, and defecation the most under-rated.”
After thousands of hours of intensive research, I have come to three hypotheses:
People will often do what is uncomfortable to themselves to pleasure their partner. This can take many forms, anal sex wouldn’t even rank as top 100. Examples include indulging in foot/amputation/midget/etc fetishes, going to an opera, watching chick flicks/football games/jazz concerts, and so on.
Some people take great pleasure in anal sex, and this results in observer bias. A handful of pornstars, e.g. Annabel Chong, make a lot of anal sex videos…A Lot. If you watch enough of her videos, one might suspect that she enjoys anal sex so much that it can be generalized to the average population. Conversely though, if you follow her career, the amount of anal sex she had to endure inversely correlated to her age and popularity.
Everybody has a price. If you pay enough, anyone would be willing to do just about anything, again, anal sex being middling compared to selling your liver or kidneys, or letting somebody kill and cannibalize you.
Imho, anal sex is not meant to be pleasurable (or preferred vs penile-to-vaginal sex) for evolutionary reasons you stated, but it seems like there’s a lot of it going on for the reasons I mentioned.
Edit: Also note that the prevalence of anal sex among the homosexual community is largely exaggerated, the usual means of intercourse is mutual masturbation or oral sex, just like lesbians.
The nerve cells that sense touch (and the sphincter is full of them so that we know what’s happening down there and to know if something’s trying to crawl up it) are also the nerve cells that register pleasure when, in context, it is welcomed sensation, or, in the case of relieving ourselves, is a pleasure center feedback loop to get us to do our duty, so to speak.
Asking why the anal sphincter and the rectal muscles can be stimulated in a pleasant way is like asking why our fingers find pleasure running them through soft fur or why our back muscles find pleasure when massaged.
What confuses people is when they battle the evacuation process instead of letting it happen naturally and thus it is usually unpleasant for them. Or associating the anal sphincter with what comes out of it and the sphincter is a source of only disgust. Or if any anal pleasuring or penetration is attempted while not relaxed and it is painful in the same way if someone massaging our back puts a lot of pressure on a knotted muscle. Those people understandably would regard ‘anal’ as totally yucky and painful.
Pace Colibri, I’ve never associated that pleasant lightness of being after a bowel movement with the passage of feces through the anus–although I have [TMI] and can appreciate its use as such. It is helpful, I think, to bear in mind how such activity has been proposed by Freud the physical component of a primal psychological state. But not after every crap.
Some people who have not experienced the feeling of pleasure after a good, relaxed bowel movement will refuse to acknowledge or believe that this is possible.
Some, like you, question the need for the body to feel pleasure after a bowel movement.
The fact is that many people report this feeling and describe it in different ways.
Some describe the feeling as a
general “wellness”
“relief”
“satisfaction”
“lighter and cleaner feeling”.
Others go so far as describing the feeling as “elation” and better than sex!
This is due to the extensive sensory nerve supply in the anal region.
The process of eliminating wastes from the body is essential for it’s work and can deteriorate our health if ignored. Is it any wonder why nature designed it with “Reward” for us with a feeling of happiness after a good bowel movement?
In order to encourage us to eliminate regularly, our bodies appear to have evolved to experience this reward. Sexual intercourse is necessary for reproduction. Sex does not have to be pleasurable, but it is.
Evolution ensures that you carry out the essential bodily functions by rewarding you with a feel good factor. Deffecation is one of these functions.
In any case, why should you not feel happy knowing that you have just eliminated waste and toxic substances making yours a healthy body?
I don’t think anyone is questioning that one usually feels better after a good bowel movement. What I think is very questionable is the contention that the good feeling arises (primarily, if at all) from the sensation of feces moving through the anus. The relief and pleasure (such as it is) seems to me, and I think to most of us, to arise entirely or overwhelmingly from the fact that we no longer have that uncomfortable feeling of a full, stuffed colon.
Why are you assuming that there’s some “evolutionary advantage” involved? Evolution doesn’t work that way. There’s no “goal” to every little thing we experience.
I, too, question Colibri’s assertion (and that’s a rare and sometimes dangerous thing to do.) Defecation is as normal as breathing, and there’s nothing inherent in the act of exhaling, for example, that gives us pleasure, even if we’ve been holding our breath. If anything, it’s analogous to urinating, which, I believe, brings real pleasure, i.e. relief, when the displeasure of fullness grows, not in the “pleasure” of sending urine down the urethra.
Where on the body do we NOT feel any pleasure when touched? I think your eye is going to be the only universal, followed by anywhere someone is overly ticklish.
But we all receive pleasure from hugging. Virtually all of us enjoy having someone stroke our hair, face, arms, legs, back, etc. So, 99% of our bodies feel pleasure. That the anus is part of the 99% is really not a surprise, then. We don’t even need a defecation explanation. It would be worthy of an explanation if the anus didn’t feel any pleasure.
So, concluding that almost everything with nerve endings feels pleasure, the fact that the anus has a large number of nerve endings would lead us to conclude it will give us more pleasure than an area like our shoulders.
Of course, the anus/rectum is also right next to other sex organs. For men, the prostate gland is nearby. For women, parts of the clitoris extend into the body around the vagina so there’s some stimulation there.
But, overall… I think it speaks more of the human brain than anything else. Just about anything is pleasurable or sexy if we decide to make it that way.
Quoth John Lennon: “Sex is 99% imagination and 1% friction.” In other words, people get sexual gratification from it because in their minds, it’s sexual.
Biological equivalent of what engineers would call a “don’t care case”. That is, a lot of things in biology (just as in engineering) as a result of a design intended for other purposes, where that other purpose is not significantly thwarted by the unintended consequences. Of course, I use “design” and forms of “intention” a bit tongue-in-cheek when applied to evolutionary biology, as there is no designer or intention, but nonetheless, a “purpose” is achieved. Even when there is no teleology, it’s simpler to talk as if there were.
My wild guess, #1 applies more to women in this case, and #2 more to men due to prostate stimulation, but both still apply to both.