May 09, 2006
Lesbian Brains Respond Differently To Pheromones

Using positron emission tomography (PET) and Magnetic Resonance Imaging (MRI) Swedish researchers have found that the brains of homosexual women responded to pheromones in ways more like heterosexual men than like heterosexual women.

Lesbian and heterosexual women respond differently to specific human odours, a brain-scanning study has found. The homosexual women showed similar brain activity to heterosexual men when they inhaled certain chemicals, which may be pheromones, the researchers say.

"But our study can't answer questions of cause and effect," cautions lead researcher Ivanka Savic at the Karolinska Institute in Stockholm, Sweden. "We can't say whether the differences are because of pre-existing differences in their brains, or if past sexual experiences have conditioned their brains to respond differently."

Anyone surprised?

They used two candidate human pheromones labelled "AND" and "EST" and found that lesbian brains responded more like heterosexual male brains.

Lesbian and heterosexual women showed different patterns of brain activity while sniffing AND and EST, the study shows.

While smelling AND and EST, the brain activity pattern for lesbian women was closer to that of heterosexual men than heterosexual women, Savic and colleagues note.

Previously homosexual men and heterosexual women were found to have even greater similarity in their brain patterns when exposed to these compounds.

Lesbians didn't react in their anterior hypothalamus while heterosexual women did.

The results showed that while a part of the brain called the anterior hypothalamus -- which is linked to sexual behavior, among other things -- tended to light up in the straight women, the lesbians showed no reaction.

On the other hand, lesbians tended to react to male as well as female hormones in the part of the brain that handles routine odors.

We have preferences and desires that come up from deep in our subconsciouses which we have little control over. We have some control over how we react to the desires. But little control over the nature of the actual desires.

Share |      Randall Parker, 2006 May 09 10:48 PM  Brain Sexuality

Doug said at May 10, 2006 12:01 PM:

I wonder what effects are being produced by the chemical soup of supposed pheromones in fragrances. As I understand it, colognes include chemicals produced by women to which men respond favorably, and perfumes include chemicals produced by men to which women respond favorably. (The idea, after all, probably isn't so much to make the wearer of the fragrance attractive as to make the fragrance attractive to the wearer.) If men really are running around wearing chemicals produced by women, and women are running around wearing chemicals produced by men, I wonder about the effects on attraction. For that matter, our daily ritual (at least in America) of washing off whatever might naturally give us an odor must wash off a lot of pheromones, as well (by hypothesis that there are significant human pheromones in the first place). I wonder how much attraction is confounded by that practice?

It seems contraception, abortion, and the features of feminine psychology (such as anxiety) and feminist education (such as careerism) that prompt the use of contraception and abortion are the main reasons for low fertility rates in wealthy countries. However, it's at least plausible there are effects produced by the sorts of pheromonal androgyny about which I've speculated.

wcw said at May 10, 2006 6:36 PM:

Alternately, humans could be wired for low fertility when wealthy and comfortable.

Call me crazy, but I can see the evolutionary pressures for it.

jos bleau said at May 11, 2006 7:54 AM:

Or maybe this isn't science at all?

Two groups of twelve women each is simply too small to be statisitcally signifigant. Pet scans are technicolor Rorshack tests - highly ambigous and with reltively low agreement between different interperters of the same results, compared to other tyrpes of scans. The scientists doing the interpreting of the scans knew which subjects were which. And the scientitst had a financial interest in the outcome of the research.

This is everything that is wrong with research today - a waste of time and money that could not have prodcued useful results.

Randall, if your blog is to retain its value you need to be calling this stuff for what it is - useless.

I'm disapointed in you.

Jake said at May 11, 2006 10:51 AM:

This study confirms what I knew all alone. Most men are lesbians.

Randall Parker said at May 11, 2006 5:41 PM:

Jos Bleau,

If you want to get all high and mighty at least be rigorous about it. If the scientists do stand to make money off their pheromone candidates I do not see how the different response by lesbians would increase or decrease the economic value of their chemicals. Lesbians are, after all, a small fraction of the total female population.

As for PET scans validity: Depends on how they processed the data. Did they do automated scoring of levels of activity in brain regions using image processing algorithms? Or did they eyeball and make their own scores? Also, how different were the levels? If the differences were small and they eyeballed the scans then their own judgements could affect the results. But if the differences were large and/or they scored using software then their own judgements might not have entered into it.

Jos Bleau said at May 12, 2006 8:59 AM:

"If the scientists do stand to make money off their pheromone candidates" I don't know if they do, and you don't either, as you admit, but if you think that would be the only way to profit from this then your imagination is lacking.

"As for PET scans validity" - well, with such a tiny sample size, and the results being interperted by scientists who knew which test subjects were which, then the validity is so small as to be none. Even if PET scans produced a very high degree of simularity of analysis between interpreters, which they most assuredly don't.

Randall, this is a fight I want to loose - because I want you to be right about the meta-question, namely that this is research of sufficient quality to merit our attention.

But so much of what passes for journalism, in sceince and elsewhere, is simply no-value added re-writes of press releases. It's not enough to put together quotes from several differnt stories on the same subject - we need you to value-add, not just aggregate uncritically.

That's not really helping us or you.

Randall Parker said at May 12, 2006 4:27 PM:

Jos, you stated confidently,

And the scientitst had a financial interest in the outcome of the research.

Then you contradicted yourself:

If the scientists do stand to make money off their pheromone candidates" I don't know if they do, and you don't either, as you admit,

Small sample sizes: Science is expensive. Lots of work gets done with smaller sample sizes due to costs. Brain scans aren't cheap. I don't come across many brain scan experiments involving hundreds of people. I think A) the results are interesting and B) not terribly surprising. Of course people with different sexual orientations have different things going on in their brains.

This experiment does not exist in surprising isolation. There's other work out there showing biological differences between people with different sexual orientations. The researchers and writers on the general area (and I've corresponded with one such researcher and one writer who has reviewed the research for a book) have used all sorts of tools such as sensors on genitals to gauge sexual arousal and measures of pupil dilation among other measures.

Females are different than males in a very important respect. Males get their orientation from their arousal patterns. So-called bi-sexual men are all either homosexual (in most cases) or heterosexual when by arousal patterns measured by genital sensors of reactions to pictures. Females are more complicated. Their sexual arousal is not toward a particular sex so much and their general orientation toward one sex or another is not driven by their arousal patterns. Rather, they end up having sexual relations with the sex that they are attracted toward in other ways. By this measure homosexual women are different than heterosexual men even though they both are attracted to females.

Jos Bleau said at May 13, 2006 10:35 AM:

Ah, since scientific validity is expensive we should be prepared to do without it, if the results are interesting and tell what we already think we know.

Are you talking about science - or fairey tales?

Bob Badour said at May 13, 2006 11:11 AM:


Do you know what the confidence levels were for the study? If not, the best you can claim is we do not know how valid the study is. If the study results were surprising or seemed to contradict other findings, one would naturally want extensive follow-up studies to verify the result.

If the study results are not surprising and seem totally consistent with other findings, then the results are mildly interesting and require no heroic efforts. That's the way science works.

Similarly, one will spend more verifying the non-euclidean nature of our universe than one will spend verifying the increased range of long-range artillery using angles closer to 90 degrees than 45 degrees. (Long-range artillery sends projectiles on elliptic paths with little friction in the upper atmosphere rather than on parabolic paths through dense air.)

Randall Parker said at May 14, 2006 7:39 AM:


It is very routine to do cheaper smaller scale studies, see an interesting phenomenon, and then either gradually scale up to bigger studies of the same type or look for other ways to confirm the finding. Why spend the big bucks up front before finding something interesting? The small bucks studies provide results to justify the big bucks studies.

Such a study as this does not absolutely prove anything. But the bulk of very interesting studies that get reported do not, by themselves, prove anything. In this case I fully expected to see differences in heterosexual and homosexual brains from brain scans due to other reports I've read about sexual differences and discussions I've had in a private forum with sexual difference researchers. This is another piece of evidence that brains of males and females and heterosexuals and homosexuals operate differently. I've got other reports on this theme in my Brain Sexuality category archive.

Avril said at January 22, 2007 12:03 AM:

So now i've read this...and wonder...So there's this girl who's a lesbian...and so with help of her pheromones she is supposed to attract girls; but she only keeps attracting guys. my question is, is she really lesbian?? or what's going on there..??

Joshua Soapes said at May 26, 2008 2:14 AM:

Everyone knows what time it is when they walk into a room and some try to confuse themselves and get all worked up(chimpanzee style), instead of realizing the experience and possibilites that are in the room(human style). The time changes from room to room and changes occur from room to room and mixing is the best and will make that person more able to accept what it is they are here for. Psychological meandering and defiance is a complex way of dealing with it and it is a cloak and when cloaks persist long enough change is happening. Avril, Jos, Doug, WCW, I have this feeling that some know what I am talking about and some don't if you know than we are 100% correct. Metaphors with words ommitted is a good way we all know what we are talking about while those who are opposed deep down can move along and save there critisism it is the only way to make alliances. And agreement about what is written back in forth is known without any bias.

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