Clearly the reason that sex is so pleasurable is because that motivates us to have a lot of it. It is evolutionarily advantageous to desire the things that make us more fit. Sex feels good, we seek that feeling, we have a lot of sex, we reproduce more.
But that is not the only way to get motivated. It is also advantageous to derive pleasure directly from having children. We see children, we sense the joy we would derive from our own children and we are motivated to do what’s necessary to produce them, even if we had no particular desire for the intermediate act of sex.
And certainly both sources of motivation operate on us, but in different proportions. So it is interesting to ask what determines the optimal mix of these incentives. One alternative is to reward an intermediate act which has no direct effect on fitness but can, subject to idiosyncratic conditions together with randomness, produce a successful outcome which directly increases fitness. Sex is such an act. The other alternative is to confer rewards upon a successful outcome (or penalties for a failure.) That would mean programming us with a desire and love for children.
The tradeoff can be understood using standard intuitions from incentive theory. The rewards are designed to motivate us to take the right action at the right time. The drawback of rewarding only the final outcome is that it may be too noisy a signal of whether he acted. For example, not every encounter results in offspring. If so, then a more efficient use of rewards to motivate an act of sex is to make sex directly pleasurable. But the drawback of rewarding sex directly is that whether it is desirable to have sex right now depends on how likely it is to produce valuable offspring. If we are made to care only about the (value of) offspring we are more likely to make the right decision under the right circumstances.
Now these balance out differently for males than for females. Because when the female becomes pregnant and gives birth that is a very strong signal that she had sex at an opportune time but conveys noisier information about him.That is because, of course, this child could belong to any one of her (potentially numerous) mates. Instilling a love for children is therefore a relatively more effective incentive instrument for her than for him.
As for love of sex, note that the evolutionary value of offspring is different for males than for females because females have a significant opportunity cost given that they get pregnant with one mate at a time. This means that the circumstances are nearly always right for males to have sex, but much more rarely so for females. It is therefore efficient for males to derive greater pleasure from sex.
(It is a testament to my steadfastness as a theorist that I stand firmly by the logic of this argument despite the fact that, at least in my personal experience, females derive immense pleasure from sex.)
Drawing: Misread Trajectory from www.f1me.net
16 comments
Comments feed for this article
May 30, 2011 at 11:42 pm
John Hayes
More pleasure from sex…and less pleasure from kids?
May 30, 2011 at 11:46 pm
jeff
You are right that is the more relevant question. As it happens, in my personal sample, I have but only one data point to measure the second dimension. (Last I checked.) And she is my equal on both.
May 31, 2011 at 6:56 am
Joshua Gans
Umm, I’m sorry you were saying that what (?) happened when you saw cute children?
May 31, 2011 at 7:07 am
Jason Collins
There is a lot to be said for revealed preference:
Gender Differences in Receptivity to Sexual Offers by Clark and Hatfield (1989): According to cultural stereotypes, men are more eager for sex than are women; women are more likely to set limits on such activity. In this paper, we review the work of theorists who have argued in favor of this proposition and review the interview and correlational data which support this contention. Finally, we report two experimental tests of ihis hypothesis. In these experiments, conducted in 1978 and 1982, male and female confederates of average attractiveness approached potential partners with one of three requests: “Would you go out tonight?” “Will you come over to my apartment?” or “Would you go to bed with me?” The great majority of men were willing to have a sexual liaison with the women who approached them. Women were not. Not one woman agreed to a sexual liaison. Many possible reasons for this marked gender difference were discussed. These studies were run in 1978 and 1982. It has since become important to track how the threat of AIDS is affecting men and women’s willingness to date, come to an apartment, or to engage in casual sexual relations.
http://www.informaworld.com/smpp/content~db=all~content=a904726826
May 31, 2011 at 9:04 am
Koenfucius
I wonder whether, in addition to the opportunity cost, women might not also be influenced by a perceived optimum number of offspring. If they have attained that optimum, their desire to have more sex (which would lead to more children) would decline. Men might not be subject to such limitations.
December 2, 2012 at 12:31 am
Aida
Quite an interesting qusoiten. In my view is about putting myself in the position of my partner and asking myself how would I like if my partner would do that to me? Would I feel disrespected, put aside, angry, sad? Depending ofnthe type of relationship you have I have seen couple agreeing about when traveling alone having an affair with no repeats is tolerate. Others agree to have a third or another couple for sexual encounter together. My point is that there are many agreements for different couples and we need decide what we feel comfortable with if deciding to experiment with outer partners. I agree that if we have parnter on the side without agreements this extra partner may want to be number one and dislodge the current partner. That is looking for troubles.
May 31, 2011 at 10:50 am
Dennis
A consequence of this would be that species for which nature selects monogamy will enjoy sex less, since there is less noise for the male from female pregnancy.
May 31, 2011 at 8:05 pm
Chris
Would we not expect the party with the higher cost (opportunity or otherwise) to have to enjoy sex more in order to participate in it?
June 3, 2011 at 7:16 am
Trinity River
That sketch made me laugh so hard I almost spit out my coffee.
June 3, 2011 at 8:44 am
inkisntenough
admittedly, i skimmed through this one. there were too many big words and ideas. i like simplicity. but i must ask…are you proposing that the only reason to have sex is to reproduce? because i like to have sex because it feel good. especially when it’s with a toy and i have to do no work. it’s less fun when i have to do it with my boyfriend and have to work for it. who’s with me?
June 6, 2011 at 8:05 pm
JOSE
One important point missing here is that of monogamy. In line with Jeff arguments, recent anthropological findings suggest that the human being became monogamic about 50.000 years ago.
The reason why monogamy is a better evolutionary fit than polygamy is that with monogamy the kid has “a father” and, hence, her survival probabilities increased.
A deterioration in the survival probabilities of kids is needed for this change to occur. This will most likely be the consequences of a substitution from genes to culture, in the evolutionary equation…
December 14, 2012 at 9:21 am
ezra abrams
2,000 years ago, the greeks asked the hermaphrodite, the only person with knowledge of both man and woman, and it replied that the ratio was greatly in favor of the woman.
January 15, 2013 at 8:32 am
Jonathan Tweet
Men pursue sex more avidly, but women enjoy it more (when it’s right). Men evolved to be driven by a need for sex, but that’s different from actually enjoying it. A man’s physiology drives him to have sex, preferably with multiple partners. A woman’s physiology leads her to bond with the right guy when he comes along (or unfortunately, even the wrong guy).
September 3, 2013 at 11:18 am
John Mackowiak
I have 4 grown offspring and a wife of 38 years, all of which I love dearly. In my geezer years, I wonder if love is the most conspicuous economic irrationality.
April 29, 2017 at 2:50 pm
David Friedman
Casanova, arguably an expert on the subject, discusses the empirical evidence in his memoirs, with the opposite conclusion. He has observed the pains of childbirth, concludes that if he had to go through that he wouldn’t risk it by having sex, observes that women do, hence that they must enjoy sex more than he does.
October 15, 2017 at 12:49 am
Kokilaben Hospital India
We are urgently in need of kidney donors for the sum of $450,000,00,(29199375.00 Indian Rupee) Reply via Email only For more info Email: kokilabendhirubhaihospital@gmail.com