Born that gay
Do recent neurological studies prove once and for all
that homosexuality is biological?
A study several years ago explored this subject.
See what you think after reading this latest scientific study about why we
are gay.
As the accuracy and resolution of brain imaging improve, we can expect
virtually all behavior to be shown to be associated with demonstrable brain
changes. It shouldn't come as a surprise that imaging studies of sexual
orientation are increasingly revealing anatomic and functional differences
between "straight" and "gay" brains. But demonstrating such changes doesn't
answer the age-old question of how much our sexual preferences are innate and
how much they are fueled by environmental exposure, cultural norms and conscious
personal choices.
One way to distinguish the effects of nature from nurture
would be to look at brain regions believed by neuro-anatomists to be fully
formed at birth and impervious to subsequent environmental effects, both
physical and psychological. Focusing on such brain regions, a research team at
the Karolinska Institute in Stockholm, Sweden, headed by neuroscientist Ivanka
Savic, obtained MRIs for 90 adult volunteers -- 25 straight men, 25 straight
women, 20 gay men and 20 lesbians. Using the latest quantitative techniques for
assessing cerebral symmetry and functional connections between various areas of
brain, Savic was able to demonstrate highly statistically significant
differences between straight and gay brains. Gay and lesbian brains more closely
resembled the brains of straight volunteers of the opposite sex than the brains
of heterosexual members of the same sex.
In their study, reported in the June 16, 2008, issue of the
Proceedings of the National Academy of Sciences, Savic said, "This is the most
robust measure so far of cerebral differences between homosexual and
heterosexual subjects." Although Savic admits that her study cannot distinguish
between genetic or prenatal intrauterine environmental changes, such as relative
differences in sex hormone levels, her studies do suggest that our sexual
preferences are, at least in large part, determined by the time of birth.
Not long after reading the study, the author got a call from
neurologist
Jerome Goldstein, M.D., 67, once a fellow resident in the UCSF
neurology training program. This fall, Goldstein, an internationally respected
headache researcher and sometimes controversial gay activist, is giving a series
of lectures on the innate biology of gayness. He was phoning to ask if I had
seen the study and if I might write about the latest scientific evidence
supporting the biology of gayness. I decided to interview him instead. Goldstein
is compact, rapid-talking and constantly on the verge of impatience. Yet during
our conversations he was subdued, confessional in tone, with frequent pauses to
gather his thoughts; the seriousness of his concerns was palpable.
Jerry,
you've been an outspoken gay activist for 40-plus years. Why the sudden interest
in the biology of sexual orientation?
I was aware that I was attracted to men by age 8, even though I did not
have any gay sexual experiences until I was 19. Meanwhile, despite having no sex
or even a clear understanding of what homosexuality meant, virtually everyone
that I encountered, including my dear parents, made a point of telling me that
homosexuality was dirty, sinful and a phase that would pass.
Beginning my
sophomore year in college, and before my first gay experience, I began the
endless rounds of psychiatrists and counselors. I even tried to modify my
behavior to make it acceptable. Sadly, even though I now know better, and am
fully aware of the overwhelming evidence as to the underlying neurobiologic
predisposition to gayness, I have never been able to entirely shake this feeling
of guilt and wrongdoing. Future generations should be spared. Right now, I'm
interested in seeing that good science prevails over outdated, misguided
psychology and false-headed thinking that homosexuality is a conscious choice.
Do you think people accept that homosexuality arises out of
biological predispositions?
Only on the surface. Down deep, there's a lingering suspicion that,
even if the cause is biological, there is something intrinsically wrong with
being gay. It has been 35 years since homosexuality was removed from a
psychiatric diagnostic category and we [still] don't see the changes in the way
people think. Sadly, even our major neurological societies haven't taken a
serious look at the biology of sexual orientation. For example, when was the
last time that you saw the American Academy of Neurology even address the
subject? And the general public? Just listen to right-wing talk show hosts
offering to pray for my sins. Or look at the damage caused by the religious
right and its "conversion therapy," which attempts to alter an inborn
characteristic of human behavior. I don't want pity and sympathy, I want
scientific understanding based on logic and reason.
Could you
give me a brief rundown of what you think is the most compelling evidence
supporting the biology of gayness?
Keep in mind that sexual orientation is exceedingly complex and not
reducible to a single gene or hormonal aberration, or explained by demonstrable
anatomic brain differences. But by examining multiple lines of evidence, you can
begin to connect the dots as to how biology influences sexual preferences. With
these caveats in mind, let's look at the history leading up to the present
functional imaging studies.
In 1991, Simon LeVay, formerly a professor of neuroscience at Harvard
and the Salk Biological Institute, claimed to have discovered specific anatomic
differences between gay and straight brains, primarily in a region of the
hypothalamus believed to have a major influence on sexual behavior. By the way,
this region's fetal development is greatly influenced by the levels of
intrauterine testosterone, a major reason why intrauterine shifts of sex hormone
levels are thought by some researchers to contribute to sexual preference.
But LeVay's work was considered controversial, nonreproducible, and
part of a gay political agenda. The real take-away was the promise that
neuroscience might one day offer better insights into the origins of
homosexuality.
At the same time, there were a variety of quasi-scientific studies
claiming to uncover markers for "gay tendencies." One suggested that you could
tell whether or not you're gay by whether your hair whorl -- that patch of hair
on the crown of your head -- curled clockwise or counterclockwise. Another
suggested that you could tell by the relative symmetry of your second and fourth
digits. Those studies weren't exactly good science and certainly didn't make the
biology of sexual orientation an attractive area for basic research funding.
Early genetic studies also ran into major criticisms. In the early
'90s, Dean Hamer of the National Cancer Institute raised the possibility of "a
gay gene." His studies met the same criticisms asserting that that single genes
don't cause complex behavior. On a
YouTube
video, Hamer denies the idea of a single gene for gayness.
But what has emerged from the genetic approach is incontrovertible
evidence that sexual preference runs in families. Several independent
large-scale studies show that a man with a gay identical twin brother will have
between a 33 and 52 percent chance of being gay -- a rate far higher than is
seen in the general population. But even here, one could argue that half to
two-thirds of genetically similar twins will not have the same sexual
orientation. Naysayers have used this fact as evidence that, even in the face of
similar genetics, each of us retains the ability to consciously choose and
control our sexual preferences.
Of course, this is a ridiculous argument. Genes can be variably
expressed, depending upon environmental factors. And no one is saying that genes
are the sole cause of sexual behavior; nongenetic factors are likely to also
play a major role. It's entirely conceivable that identical twins with a similar
genetic predisposition for homosexuality but exposed to different intrauterine
testosterone levels will end up with different sexual orientations.
Let's talk about your take on the new brain-imaging
studies.
Begin with Dr. Savic's work on pheromones. It's fairly common knowledge
that, throughout the animal kingdom, sniffing chemicals secreted by other
members of the same species -- pheromones -- can invoke innate behaviors such as
a flight response in aphids, aggression in bees, trail marking in ants. We
forgive our pet cat for marking our favorite couch as "her territory." All of
these are basic survival techniques with clear evolutionary benefits. Ditto for
chemicals involved in "being in heat."
What's fascinating about Savic and her colleagues' study was their
ability to test the role of pheromones in identifying human sexual orientation.
Functional imaging studies or PET scans of heterosexual controls were
compared with a group of gay and lesbian volunteers. All subjects were asked to
sniff gender-specific sex-hormone-like compounds: AND for the androgen-like
pheromones secreted by males and EST for the estrogen-like pheromones secreted
by females.
To enhance normal reproduction, you'd expect that males would be
attracted to EST and females to AND. But Savic found that these self-declared
gays and lesbians process these pheromones differently than their heterosexual
counterparts.
When exposed to the male pheromone AND, homosexual men tended to respond
similarly to heterosexual women, both in brain location and degree of
activation. On the other hand, gay women responded to EST similarly to straight
men.
In short, it looks as though straight men and gay women processed similarly
while the converse is true for straight women and gay men.
But her pheromone study still doesn't answer the nature-nurture
question. These PET scan differences could reflect the consequences of a
behavior rather than necessarily being indicative of the cause of the
behavior.
But that's what makes her study so important, and allows her to
draw the most important conclusion -- that sexual orientation is determined
prior to exposure to life's environmental influences. Savic has assured me that
these findings aren't "learned" but rather reflect either genetic or
intrauterine developmental differences. And, unlike some of the early
researchers, Savic can't be accused of having a gay political agenda or bias.
Her field was originally epilepsy research. She inadvertently stumbled onto the
pheromone sex differences while studying how smells might trigger temporal lobe
epilepsy.
You've seen the studies. How impressive are the differences?
There are obvious-to-the-naked-eye differences in cerebral symmetry and
in the functional connections in various portions of the limbic system,
including the differing degrees of connectivity between amygdala and other brain
regions critical for emotional responsiveness. It's as though you can actually
see the brain changes that most gays have always suspected; and, believe me,
it's a great relief to realize that these findings are clearly present at birth
and aren't anyone's "fault." They simply are [present] in the same way that one
has blue eyes or red hair.
No more and no less.
In thinking about sexual orientation as a choice, isn't
there also the problem of how unconscious biological traits affect conscious
decisions?
Of course. In a way, choosing a sex partner is like choosing what you
eat; it might feel like a choice, but biology plays a major, though unconscious,
role.
I presume that you are alluding to the recent studies of
the genetics of taste?
Yes. Take our ability to taste bitterness. A single gene, isolated in
2003, determines whether or not foods such as Brussels sprouts are experienced
as bitter. Remember how our parents insisted that we could learn to like
Brussels sprouts; if we didn't, we were accused of being finicky eaters, or
worse. Now, we would be sent for genetic testing.
Are you equating homosexuality with a taste for Brussels
sprouts?
Very interesting and funny. But sex is much more complex and
emotionally charged as a point of discussion than taste. But yes, in a larger
sense, genetics helps determine the shape of desire.
Are
you suggesting that outside influences -- parental, peer group and general
cultural -- aren't important in determining our sexual preferences?
Not entirely. I'm saying that these influences are far less potent than
the biological. Certainly there are a variety of strictly
environmental circumstances, such as long-term prison incarceration, that might
trigger homosexual behavior. But then you run into the reverse argument. Given
that lots of men are confined to prison, only some end up with homosexual
behavior. Perhaps these circumstances still reflect a combination of biology and
environment. Right now, all bets are off.
There is the additional problem that you discussed at length in your
recent book,
"On Being
Certain," namely, how conscious decisions can be affected by unconscious
biological mechanisms. The same biology that affects our sexual desires may also
affect how we consciously think about these desires.
In
a separate study (PDF), Savic has shown that differential
responses to pheromones even affect how we determine the relative masculinity or
femininity of facial images. Savic presented male volunteers with a series of
facial images and asked them to rate the faces on a scale of masculine to
feminine. When inhaling a masculine pheromone, the volunteers perceived the
faces to be more masculine than when they were exposed to estrogen-like
pheromones.
What's so intriguing about this study is that it shows how simple
chemicals can actually affect our visual perception of gender. It's not a great
leap of imagination to see how these same chemicals might influence whether an
adolescent male chooses to read a muscle magazine or Playboy.
Do you think these studies can help counter fundamentalist
arguments that homosexuality is evil?
Accepting sexual preference as an innate characteristic is an essential
first step. But this sidesteps the more deep-seated gut sense that homosexuality
isn't natural and goes against the laws of nature. This argument can be
partially defused by recognizing how ubiquitous homosexual behavior is in the
animal kingdom -- starting with the lowliest fruit fly. I'm sure you're aware
that there is a single gene, which, in the fruit fly, can turn on and off
homosexual behavior.
But in the end, I suspect that real acceptance will only come about
when we have a much more comprehensive view of how the mind works, including how
we make conscious choices versus how much of our apparent willfulness arises out
of involuntary biological mechanisms.
Let's all pay homage to the fruit fly by grabbing your snuggle buddy and
giving him "Mega Hairy Muscle hugs". And forget the mind games, after all, we
are what we are.
So remember to eat your brussel sprouts. And throw in some spinach for good
measure.
Your musclebear Popeye may be closer than you think. WOOF
Hey Woody,
