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Vanity, thy name is pukestain
By Carol Snow
There's nothing like a (fleetingly) sick kid to highlight the humiliating flexibility of your maternal code
(03/09/98)

Time for 1 Thing
By the Salon staff
A guide to fast-forwarding to the most sensuous moments on film
(03/06/98)

Confessions of a video-renting junkie
By Kate Moses
Before she had kids, she could handle two or three movies a night. Now just one leaves her with bleary eyes and a pounding head in the morning
(03/06/98)

The price of eggs in America
By Cynthia Joyce
Which comes first, the donor or the egg?
(03/05/98)

Second Thoughts
By Sallie Tisdale
High school doesn't need to be fixed; it needs to be reinvented
(03/04/98)

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Why it's time
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BY ROS DAVIDSON | One of the questions that has dominated the nature vs. nurture debate is that of sexual orientation -- are there physiological differences that determine who is gay and who is lesbian? Though researchers have detected differences in the brains of gay and heterosexual men, evidence of biological variations in women had never been reported until last week, when researchers at the University of Texas released their findings that the auditory systems -- specifically the inner ears -- of lesbians seem to operate more like those of men than those of heterosexual females. The findings were the result of a study in which microphones were placed in the external ear canal of 240 people who had previously been questioned in detail about their sexuality.

Salon talked with the head of the study, Dr. Dennis McFadden, a professor of experimental psychology at the University of Texas-Austin, about the implications of his findings.

So you've found the first strong evidence of a physical difference between straight and lesbian women?

To my knowledge, it is the first physiological concomitant to homosexuality in females. There are a few claims, as you may know, of differences in males in various brain sites. But this is, as far as I know, the first time for females.

What exactly did you find?

A normal inner ear, a cochlea, actually makes sounds -- as well as receives and processes sounds -- and these are known as "otoacoustic" emissions. The particular kind of otoacoustic emission we were studying is very much like an echo. You put in a very brief sound, a click, like the snap of a light switch, and there will be an echo given off by a normal-hearing ear. They are very idiosyncratic. The strengths or magnitude of the sounds differ from one individual's ear to another's, although they're quite constant within the individual's ear. Females tend to have much stronger otoacoustic echoes or emissions than males.

Why are females' echoes stronger?

Females tend to have much better hearing sensitivity than males. Their inner ears also tend to make stronger sounds, although the sounds have no real purpose in themselves.

I was interested in the origins of this. Something we did years back was to measure the otoacoustic emissions in opposite-sex twins. And what we found was that those females had otoacoustic emissions that were like those of males, not other females. Since we knew from other research that otoacoustic emissions are reasonably stable through life -- infants and children have them in the same pattern and manner that adults do -- the implication was that those females with male twins had in fact been born with weaker cochlear amplifiers, that is, with weaker click-evoked emissions. So that leads you to try and imagine what kinds of mechanisms might have been operating prenatally to produce this effect. What we came up with was the suggestion that those females who had male twins were exposed to higher levels of androgens than females ordinarily get in the womb. And where those androgens came from was from their male twins.

But female co-twins are not more likely to be lesbian, I assume. So what does this say?

Right. There's not a greater incidence of homosexuality among females with male twins. But it still led us to wonder if there might be a difference between homosexuals and heterosexuals. So we did this experiment, and in fact we did find that the strengths of these echoes were smaller in homosexual women than in heterosexual women -- that is, the magnitude of their echoes was between that of heterosexual females and heterosexual males.

So why aren't more female twins lesbian?

Well, we aren't sure why. But if the suggestion that we're offering is correct -- that there's been some prenatal "masculinization" in the womb to account for both the changes in the auditory system and later on in some brain centers in homosexual and bisexual women -- it suggests that the opposite-sex female twins are not getting quite as strong a dose of the androgens, and whatever brain centers are responsible for sexual preference are not being affected by them.

There's any number of possible reasons why the latter might occur. It may be a matter of timing -- that the high dose of androgen comes along in homosexual and bisexual women at the right time to masculinize the brain centers for sexual preference, but is off some for female twins, so their auditory systems get masculinized but not the other brain centers. There's also the question of androgen sensitivity -- that receptor sites can be hypersensitive in some situations. So it may not be that homosexual and bisexual women are exposed to more androgen, but that they're more sensitive to it and are absorbing more of it.

How dramatic was the difference between the echoes in homosexual women and those in heterosexual women?

It's a big difference -- a monstrous difference. The difference between heterosexual males and females is five or six decibels, while homosexual and bisexual females are halfway in between -- that is, about three decibels weaker than heterosexual females. Remember though, we are talking about group differences, how each group differs on average. It's a continuum. You can't predict the sexual preference of an individual with any accuracy from knowing the size of the echo response. In the same way, while men tend to be taller than women, you can't predict whether an individual is a man or woman from that person's height.

N E X T+P A G E: Why are lesbians born?