May 28, 2006
Dopamine Receptor Genetic Variant Influences Sexuality

Genetic variations in a dopamine receptor influence sexuality (same article here)

New evidence that individual differences in human sexual desire can be attributed to genetic variations has been revealed by a research group headed by a professor of psychology at the Hebrew University of Jerusalem. The findings are believed to have an impact on people’s understanding of their own sexuality as well as to how sexual disorders may come to be treated in the future.

An article on the topic appears currently in Molecular Psychiatry online. The study represents the combined efforts of researchers directed by Prof. Richard P. Ebstein, of Herzog Hospital and the head of the Scheinfeld Center for Human Genetics in the Social Sciences of the Psychology Department at the Hebrew University, and a research group headed by Prof. Robert H. Belmaker of the Psychiatry Division of Ben Gurion University of the Negev.

The article provides, for the first time, data that common variations in the sequence of DNA impact on sexual desire, arousal and function and lead to differences and diversity of the human sexual phenotype.

Did anyone previously not expect this to be the case? The press release gushes on about how this is a revolutionary discovery that will affect how we look at sexuality. Maybe that is true for some people who do not want to accept that genetic variations play a large role in determining our desires, dislikes, and behavioral tendencies and abilities. But I expect genetic roles in all sorts of aspects of cognitive function and in the peripheral nervous system. I just am eager and impatient to get to the details so we can work out the implications.

Self-reports on sexuality correlate with DRD4 dopamine receptor genetic variations.

In this latest study, the Israeli investigators examined the DNA of 148 healthy male and female Israeli university students and compared the results with questionnaires asking for the students’ self-descriptions of their sexual desire, arousal and sexual function. The results showed a correlation between variants in the D4 receptor gene – which is responsible for producing the dopamine receptor protein (DRD4) – and the students’ self-reports on sexuality.

Sounds like only 10% had moderate sexual desire and most were in the "depressant" category. I bet divorces are more likely between members of a couple who have radically different levels of sexual desire. Therefore genetic tests may eventually help to predict likelihood of marital success.

Interestingly, some forms of variants in this gene were shown to have a depressing effect on sexual desire, arousal and function, while other common variant had the opposite effect – an increase in the sexual desire score. The latter is believed to be a relatively new mutation, and it is estimated that it appears in Homo sapiens “only” 50,000 years ago at the time of humankind's great exodus from Africa. Approximately 30% of many populations carry the heightened arousal mutations, while around 60% carry the depressant mutation.

Did the migration from Africa take humans into areas where so much food was available that it was selectively advantageous to mate and reproduce more often?

Which are the populations that have a higher average level of sexual arousal? Does the level of sexual arousal correlate with other characteristics?

The discovery of a role for DRD4 in sexual arousal makes it a candidate target for drug development. Further research into the mechanism for how it causes this effect will likely lead to identification of other targets for sexual arousal drugs.

The investigators predict that as a result of their work, and other advances in neurosciences focusing on sexual behavior, a conceptual change will result, in which new therapeutic pathways will be developed for treatment of sexual dysfunctions based on a rational pharmacogenetic strategy. Additionally, the investigators note that many variations such as “low sexual desire” may be quite normal and not necessarily a product of dysfunction.

Viagra, Levitra, and Cialis are not enough. People want more ways to make themselves sex-crazed. Don't worry. The cheaper genetic sequencing gets the more genetic variations we'll discover that contribute to sexual arousal and the more targets for drug development that will be identified.

When it becomes possible to select the genetic variants offspring will get will more people select higher, lower, or medium sex drive genetic variations? I'm guessing women will want to give their daughters genetic variations that make multiple orgasms very easy. Will people want their kids to walk around constantly craving sexual experiences?

Share |      Randall Parker, 2006 May 28 04:00 PM  Brain Sexuality


Comments
Robert Schwartz said at May 28, 2006 7:46 PM:

I am guessing that you are not married.

Dave said at May 29, 2006 8:11 AM:

But sexuality is not just genetics. In prisons for example many otherwise 'straight' men become male on male rapists, and sometimes when people spend a very long time alone, like on an Island or a small ship they can have 'feelings' that they wouldn't usually have.

CASpears said at May 29, 2006 8:26 AM:

I think the point is that people are sexual by nature, and that varies according to genes, it is not trying to argue how people act out this sexuality, that is more complex. Some act it out by raping children, some act it out with homosexual sex, others by heterosexual sex, but the mechanism that controls all of this sex is genetically based...how it is expressed or why it is expressed in certain ways is still not yet known.

crush41 said at May 29, 2006 12:01 PM:

Anything on IQ and sexual impulse?

I would guess most parents would elect for their children to be less amorous, not more. Is a good orgasm part of what the all-American dad has in mind when he's planning on how he'll help his kids have the best life possible? Certainly I would be a lot more productive, wealthier, and have more free time to engage in constructive activities if not for the drive of a typical 22 yo. I'd probably be happier too. Or at least life wouldn't be as emotionally capricious.

Robert Silvetz said at May 29, 2006 12:41 PM:

-- Additionally, the investigators note that many variations such as “low sexual desire” may be quite normal and not necessarily a product of dysfunction. --

Uh ... in a word -- NO. I will take these researchers on any day of the week. I don't buy these researchers conclusions for a second.

These guys got to go read the literature on the relationship of testosterone to libido, in both sexes. Except at the margin, the male human has only one state -- on -- from puberty till death. Libido follows testosterone levels. In the hormonally potent female that hasn't been chemically castrated by the oral contraceptive pill, baseline testosterone is north of 350 pg/ml. In the castrated female its below 150 pg/ml and her libido is in the basement. Removal of OCP with restoration of normal SHBG levels results in testosterone north of 350 pg/ml and restoration of libido.

Hormonally normal females are cats in heat generally and off the deep end at ovulation. We are not talking 50% of women here, we are talking 95%+. Every woman who walked thru Endocrine at the university whose libido was in the toilet was on some drug/diet/OCP/tumor that tanked their free testosterone. Elimination of the offending variable restored libido, sometimes with a touch of androgen replacement for several cycles.

Men, generally potent from puberty to their late 30's, they are seeing more and more men, seemingly healthy, but with potency/libido in the toilet. Free-testorone levels seem low-normal to normal, but upon further examination, are turning out to be below their own individual baselines, cortisol sometimes thru the roof -- stress(?) related maybe too feminized a diet... who knows?

Men in their 40's, as they drive their estradiol up, drive up their SHBG and drive their free-testosterone below their potency needs. 0.5 mg Arimedix twice a week restores potency in this group. Bioidentical testo replacement for men in their 50's maintains libido easily.

I would love to take the researcher's data and stratify by free-testosterone levels. I bet the low-libido group would cluster with ultralow free-testo levels.

I would need to take a hard look at how they phrased the questions, what their assumption of normal sexual frequency is, whether the sample size was sufficient, what confounding issues they might have and what they think a good correlation is. I don't buy for a second that one lousy receptor mutation has this alleged effect unless it has an equally or stronger correlation with the free-testo levels sloshing around. Otherwise, it flies in the face of 15 years of very successful treatment of sexual dysfunction in women and men. And it flies in the face of keeping a species alive evolutionarily. Any species with our kind's long incubation and long functional adoloscence had better be frisky all the time to ensure a constant supply of useful humans.

CASpears said at May 29, 2006 12:42 PM:

Crush41: And if everyone was "a-sexual" like you describe, we would also have a worse population shortage than we already do. Nothing is wrong with the sexual impulses of a teenager or a 22 year old. It is best (biologically speaking) for women to have children in their 20's. The problem is that we have constructed a society in the last 500 years that defie s our very nature as human beings. We try everything we can do delay sexuality in "children" unnaturally because our society requires so much education that we fear sexuality will lead to children, the resulting family will hamper educational goals. We fight our nature an we wonder why we have so many social problems based around basic human impules.

Dave said at May 29, 2006 1:46 PM:

Robert, one difference in male hormones, and I am no expert in this, but is it not true that a tough life of phyical activity stimulates male hormones and that 60-70 years ago most men used to work in the fields, down mines or a poor factory enviroment, whereas now with most men do not have anything like as phyically demanding lifestyle.
Could that be one of the major reasons for the changes?

I didn't know the oral contraceptive pill had such an extreme effect as you say, its interesting, you are saying it is literally a mind altering drug making women less likely to want children. No wonder the birth-rate in the Western world is in such trouble, for example Scotlands population is declining by 10,000 every year.
Overtime, the women most likely to have families will be the ones most resistant to the affects of this drug?

-
CASpears,
The last issue of National Geographic listed the age limit on marriage around the world, it was interesting, the biggest group was 16, but the 2nd biggest was 'no age limit', here are a few examples: Brazil 12 (I don't think O'reilly would be impressed), South Africa 12, Mexico 14, Argentina and Venezuela a pregant girl of any age can get married to the father, In Nepal 7% of girls are married before they are **10**.
(if these figures are wrong sorry, I am just quoting them out of the mag)

CASpears said at May 29, 2006 4:07 PM:

Dave:

I am pretty sure your information is correct...but these countries also don't have population problems. I'm speaking more of Western countries or Westernized countries (such as in Japan, South Korea, Singapore, which also have demographic problems due to the same reasons as Europe and America). Typically in America, the only reason the population is growing is due to immigration and the fact these immigrants have more children than native born people (because they don't adopt an "American life style") and the poor, who do not seek greater education, so they start having children in high school or right after, which actually, biologically speaking was quite normal for humans everywhere (even in America until the 20th century).

Robert Silvetz said at May 29, 2006 7:56 PM:

Dave,

No question about it. 3 generations back physical activity was greater with all the benefits, some of which were probably higher baseline testosterone levels.

And yes, the pill whacks emotions -- some girls go pyscho on you -- but for the most part OCP's tend to flatten everything, obliterating the extremes of emotion and thrill. The typical comment you get from the 30% that are symptomatic enough to complain to you, is "... things feel so dull, hum-drum." A lack of zest. Between docs, we tend to believe that it is somewhere on the order of 50% of all women that get hammered this way (sorry for the pun). What is aggravating is that this has been known since the 1990's and was almost certainly suspected as far back as 1975.

It could all have been solved with bioidentical testosterone laced OCP's with a little baseline, driving up to a fake ovulatory peak at 14 days, and dropping back down. But between FDA, the breast cancer scare (real and imagined), and admitting that OCP -- the feminist savior of divorcement of sexual pleasure from reproduction -- squashed sexual libido flat as a pancake for at least 1 in 3 women... no no no ... we can't have that!

The simple truth is no woman should be on OCP's without having pre-OCP baselines of free-testosterone and post-OCP monitoring. If their free-testosterone levels get too whacked, off the OCP they should come.

g510 said at May 30, 2006 2:10 AM:

Re. CASpears, "....a worse population shortage than we already do."

Population SHORTAGE...? Global climate change, peak oil, 1/5 of humans don't have clean drinking water, and you're telling us there's a shortage...? Six and a half billion heading toward nine, when we can't even feed all the humans presently alive, and you're telling us there's a shortage...?

I say, with good science to back me up, that the sustainable population of humans on Earth, at European standards of living, is about 2 billion.

What do you say? What's the number? How many humans can we sustain right now, today, with today's technology and political arrangements, and without counting on miracles? Let's hear it, what's the number?

Or are you actually saying there's a shortage of some particular racial or ethnic group? And if so, which one?

If you decline to respond, I'll interpret that as conceding the point.

---

Arthur Clarke: Any technology that is sufficiently advanced, is indistinguishable from magic.

My corollary: Any desire for sufficiently advanced technology, is indistinguishable from the desire for magic.

Randall Parker said at May 30, 2006 5:42 AM:

g510,

If someone does not respond you don't even know whether they read your comments. But if you want to interpret that as meaning that people have bowed down to your superior reasoning then feel free to delude yourself.

As for people shortages: There's an obvious shortage of smart people. They are having fewer kids than dumber people.

CASpears said at May 30, 2006 6:48 AM:

g510:

I was speaking in indvidual (mostly developed countries) not world wide. If you are looking at the issue globally I would say there is no population shortage, but due to political/cultural barriers there is not really free flow of labor possible that will allow for a more efficient allocation of human capital on a global level. The EU still can't do this within the European Union, even with open borders (due to cultural barriers)...

Dave said at May 30, 2006 9:50 AM:

Yes CASpears I know those countries don't have population problems, that was the point I was making, we in the West have the lack of children and dramatically aging populations because of the way we infantilize young adults. Those countries don't and they don't have a lack of children. Its a difficult issue cause I think some of those age limits on marrage are far too low. A girl of 10 cannot deside who she wants to spend the rest of her life with.

g510, yes there is a population shortage, for example Scotland has a population declining by 10,000 every year, this is partly because their over educated young people move to England to get better paid jobs but also because their birth-rates are rock bottom. This is going to cause Scotland massive problems in the not too distant future as they have a rapidly aging population and a generous welfare state to support.

Talking about global population disguises the issue because many third world countries don't have birth controls at all and their population growth runs out of control until they get a famine and then loads of them die..

Anyway, I am sure the world can sustain a lot more than 2 billion people, the arguement that their could only be 2 billion people if everyone was living like Americans is just anti-American leftist nonsense.
Take for example Zimbabwe, it used to be the bread basket of Africa but now millions of them are starving, and the same could happen in South Africa as they attempt to redistribute land. Zimbabweans used to have good lives, but now look at them.

The more accurate statement would be, the world can only sustain 2 billion people (or less) if it was run by a bunch of leftist communist idiots.

-

Robert Silvetz, I am a little shocked by the implications of what you are saying, I had not heard much of it before is that my ignorance or would you say its not widely known, or is what you say debatable?

Can I ask you something else, in Britain the leftists have gone fanatical with contraception (and abortion), ie giving it to 12-13 year olds behind parents backs. A few years ago I remember someone saying these drugs had been designed and tested for adults only and I think there was some debate about whether children should be allowed to have them, is that right? I can't quite remember the exact story. If these drugs have the extreme effect you say on adults wouldn't it be particularly dangerous for teenagers who are still growing? If you articially messed with hormone levels of someone as they were growing could it not affect hormone regulation for the rest of their life?

Robert Silvetz said at May 30, 2006 12:52 PM:

Hi Dave,

What I say is always debatable -- unfortunately in this matter my certainty of being right is 100%, both because of experience and available literature. The data is there for anyone to go look for it. FuturePundit picked up on a recent article: OCP article Hardly surprising this one came from my Alma Mater.

Amusingly the blog entry mentions a 45-year gap in picking up on the side effect. The general public might be 45 years out of the loop. I was taught this side-effect as an aside in med school in 1988. The big pharma's certainly knew. Otherwise they wouldn't have done the various quiet trials with testosterone that never got published. (They worked by the way. They deliberately squashed this because of the negative publicity of admitting that for 20+ years they killed sex for millions of women. Imagine the class action lawsuit...)

Progesterone in some of the recent pill incarnations of the 90's do a little better, but I think they save libido by driving other emotions to the margin.

And, btw, one real easy way to diagnose if a spouse or girlfriend are OCP libido affected. They go sex-kitten on you in either week 3 or week 4 of the pill for about 5 days, and then revert to nothing.

I am personally furious about what we are doing to women at menarche Dave. No 12-13 year old should be on the pill. Women should have normal menstruation until physiologic puberty is ended, say around 18. We have zero concept of the long term impact of hyperestogenizing developing women. Breast cancer alone should strike fear into the hearts of everyone doing it.

Even beyond the physiologic is the psychologic. Women (and men) have to interact during puberty to get the damn sex cues right. (Take a nerd at 25, big brain -- bigger asset than a big penis -- and because he never learned the sex cues, no sex life. Take same nerd and reeducate by total immersion and watch him fly...) Hyperestrogenize a woman and she loses the ability to pick up on sex cues properly. Hyperestrogenize women before they even learn the cues... are we destroying their future ability to make good mate choices? They already are pretty bad (given a 50% divorce rate). (Oh and I don't blame men for the divorce rate. Females are the choice side of our species. With choice comes responsibility.)

Patrick said at May 31, 2006 2:07 AM:

Robert,

What does Take same nerd and reeducate by total immersion" mean in practical terms? Immersion in what? Where? Do you mean surround him with women?

(I speak as a nerd who certainly doesn't have skills with women.)

Furthermore, does your hormonal research mean that those spam ads for drugs to drive women sex-mad actually work?

Back to the actual article, I would choose my children (future children) to have strong sexuallity, that doesn't kick in until about 21 years old. That seems to me to what most parents would want.

Robert Silvetz said at May 31, 2006 12:14 PM:

Hi Patrick,

Yes. I mean throw him to the social wolves. Again, again and again. Typically, he will crash-n-burn time and again. Each time you smooth the feathers, do a quick postmortem and with the help of good friends, you keep throwing him back into the fray -parties, clubs, yoga, dance, hottubs, art classes, museums. And guess what? In about 6 months, 300 approaches, and 30 odd dates, the nerd gets it (it's really a right-brain thing! stop thinking and just do do do! until the sex cues of the conversation run smoothly.)

I'm not a dating coach and wouldn't be able to describe the 9 phases of seduction if my life depended on it. But it works. We all come complete with the right machinery (thank you evolution!). I'm grateful to the friends that propped me up back in the day until women concerns faded thru success. On occasion, I still drag a younger acquaintance into fray, they crash, and crash, and crash, you dust them off and throw them in again, and then the magic happens and off they go. I suppose the anology with learning to swim is warranted. You have to get in the water and start thrashing. Eventually you are swimming!

Oh... if a drug drives testosterone up, sexuality follows, upto a point. Too much and negative feedback on the endocrine axis drives things to zero.

Patrick said at June 1, 2006 1:44 AM:

So basically, if you are not a natural womanizer it will take months of training with a dedicated (and presumably skilled) coach to solve the problem?

I'm glad I went for internet dating.

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