We Are Our Brains

by D. F. Swaab

  Although it’s frequently assumed that development after birth also importantly affects our sexual orientation, there’s no proof of this whatsoever. Children brought up by lesbians aren’t more likely to be homosexual. Nor is there any evidence at all for the misconception that homosexuality is a “lifestyle choice.”

  The above-mentioned factors alter the development of the child’s brain, particularly the hypothalamus, which is important for sexual orientation. In 1990 Michel Hofman and I found the first brain difference in relation to sexual orientation: The brain’s biological clock turned out to be twice as large in homosexual men as in heterosexual men. At the time we were actually looking for something else. I’d previously discovered that Alzheimer’s damages the biological clock, which explains why people suffering from this disorder wander around at night and doze during the day (see chapter 18). I did some more studies to see if the same applied to other forms of dementia. In the case of AIDS dementia I found that the biological clock was twice as large as normal. Follow-up studies showed that this wasn’t caused by AIDS; it was related to homosexuality. In 1991, Simon LeVay reported a second difference in hypothalamic structure between homosexual and heterosexual men, and in 1992 Allen and Gorski found that the structure on top of the hypothalamus that connects the brain’s left and right temporal lobes is larger in homosexual men.

  Scans have also revealed functional differences in the hypothalamus with regard to sexual orientation. A study by Ivanka Savic of the Stockholm Brain Institute involved pheromones, the scented sex hormones that are given off in sweat and urine. Pheromones influence sexual behavior unconsciously. A male pheromone stimulates activity in the hypothalamus of heterosexual women and homosexual men but doesn’t provoke a response in heterosexual men. It seems that male scents don’t turn them on. Lesbian women were found to react differently to pheromones than heterosexual women. Savic also showed that heterosexual women and homosexual men had more extensive functional connections between the amygdala and other brain areas than heterosexual men and homosexual women, proving that brain circuits function differently according to sexual orientation. Functional scanning also showed changes of activity in other brain areas. In the case of heterosexual men and homosexual women, the thalamus and prefrontal cortex responded more strongly to a photograph of a female face, while in the case of homosexual men and heterosexual women these structures responded more strongly to a male face. In other words, sexual orientation is determined by many structural and functional differences in the brain, all of which develop in the womb during the second half of pregnancy. They aren’t caused by the behavior of dominant mothers, who are the traditional scapegoats in this context. Just for the record, I made a habit over the years of asking the medical students I taught (250 at a time) which of them did not have a dominant mother. No one ever raised their hand.

  HOMOSEXUALITY: NO CHOICE

  Xq28—Thanks for the genes, mom!

  T-shirt referring to research done by Dean Hamer showing that a gene for homosexuality might reside in the q28 marker on the X chromosome

  Homosexuality is God’s way of insuring that the truly gifted aren’t burdened with children.

  Sam Austin, composer and lyricist

  Toward the end of George W. Bush’s presidency, an “ex-gay movement” that regarded homosexuality as a curable disease gained momentum. Hundreds of clinics and therapists jumped on the bandwagon, and it was claimed (but not proven) that 30 percent of those who went into therapy were cured. At such clinics, you received two weeks of “treatment” for $2,500 or six weeks of treatment for $6,000. The therapists were often homosexual themselves but claimed to have been turned into family men after therapy. A countermovement with the slogan “It’s OK to be gay” claimed that the therapies involved conditioning based on stigma and shame as well as discrimination against homosexuals. In 2009 an annihilating report by the American Psychological Association (APA) confirmed that the treatments were causing a rash of suicides among patients. The report concluded that therapy to change homosexuals into heterosexuals didn’t work and that the association’s 150,000 members should stop offering it to their clients. The report stated that the best such therapy could do was to teach people to ignore their feelings and to suppress homosexual inclinations. It went on to confirm that the therapy could cause depression and even lead to suicide.

  All the research indicates that our sexual orientation is programmed in the brain before birth, determining it for the rest of our lives (see earlier in this chapter). Many structural and functional differences have now been found between the brains of homosexual and heterosexual men that must occur early on in development and can no longer be changed by the post-birth environment. Even an upbringing in a British boarding school apparently doesn’t make you more likely to be homosexual in adulthood. Initially I thought that “curing” homosexuals was a typical aberration of the Christian community in America, but I was amazed to find that it goes on in the Netherlands too. The Pentecostal Church holds meetings whose prayers can allegedly “cure” you simultaneously of homosexuality and HIV infections, after which you’re married off to a woman from the Pentecostal community. It’s not just misleading but also potentially life-threatening to make seropositive individuals think that they’ve been cured in this way and no longer need to take any medication.

  The outmoded notion that we’re free to choose our sexual orientation and that homosexuality is therefore a wrong choice is still causing a lot of misery. The stories I heard when I gave a lecture to ContrariO, a Christian gay association, showed that homosexuals brought up in the Dutch Reformed Church tradition can still struggle terribly with their sexual orientation. Indeed, until recently, homosexuality was still regarded as a disease by the medical community. Only in 1992 was it removed from the ICD-10 (International Classification of Diseases). Before that time, doctors had striven to “cure” men of their homosexuality.

  The idea that our social environment shapes our sexual orientation has led to mass persecution. The Nazi notion, as expressed by Hitler himself, that homosexuality was as infectious as the plague led to the unimaginable in Germany: first voluntary castrations, then compulsory castrations, and finally the systematic murder of homosexuals in concentration camps.

  An important argument against the idea that homosexuality is a “lifestyle choice” or caused by environmental factors is the demonstrable impossibility of ridding people of their homosexuality. Every conceivable thing that could be devised has been tried: hormone treatments, castration, and treatments that influence libido rather than sexual orientation. Electroshock therapies have been tried, as well as epileptic insults. Prison sentences have proved equally ineffectual, as seen in the sad case of Oscar Wilde. Testicular transplants have been carried out, leading to a “success story” in which a homosexual man pinched the nurse’s bottom after the operation. Psychoanalysis has also been tried, of course, as well as giving homosexuals apomorphine, a drug that induces nausea, in combination with homoerotic images, as a form of aversion therapy. The story goes that this didn’t diminish the men’s erotic desires; its only effect was to make them start vomiting as soon as the therapist entered the room. Brain operations have also been performed on homosexual prisoners with a view to reducing their sentences if the treatment proved effective. Naturally, the men all said that it was effective.

  Since none of these approaches has led to a well-documented change of sexual orientation, there can be little doubt that by adulthood our sexual orientation has been determined and can no longer be influenced. If churches were finally to accept this fact, the lives of many of their young members and clergy would be a great deal happier.

  HOMOSEXUALITY IN THE ANIMAL KINGDOM

  Homosexual behavior has now been observed in around 1,500 animal species, from insects to mammals. The male penguin couple Roy and Silo in New York’s Central Park Zoo are a famous example. They copulated, built a nest together, took care of an egg that a kindly keeper gave them (hatching it ou
t after thirty-four days), and together looked after the baby. If a female rat develops alongside a male rat in the womb, thus being exposed to more testosterone during early development, it will mount other female rats. Two percent of oystercatchers, a monogamous bird species, form a trio of two females and a male, after which all three guard the same nest. A trio of this kind produces more offspring than a conventional pair, because they are better able to look after and protect the nest.

  Behavioral scientists have also shown that homosexual behavior in animals is often used to make peace with enemies or obtain the help of others against possible attackers. Primatologist Frans de Waal has found bonobos to be completely bisexual, a perfect 3 in the Kinsey scale. Where possible, bonobos solve problems in the group by sexual means, through both heterosexual and homosexual behavior. De Waal has found that same-sex practices are displayed by other primates, too, like macaque monkeys, in addition to bull elephants (who mount each other), giraffes (“necking”), swans (greeting ceremonies), and whales (mutual caressing). He classifies such behavior as examples of bisexuality rather than homosexuality, since it only manifests itself in certain periods. However, a preference for same-sex copulation has been reported in a bird in the swamps of New Zealand, a female antelope in Uganda, and cows. Lesbian seagulls have been found in Southern California, jointly incubating a double clutch of eggs. These female gulls copulated with each other as a pair. However, this proved to be not spontaneous behavior but a byproduct of environmental pollution with DDT, leading to sterility among male seagulls and an excess of females, who formed lesbian couples (see also endocrine disruptors, chapter 2). A few male seagulls must of course have escaped the DDT and had the time of their lives inseminating all of the females at least once, but apparently the ladies had no further need of them. In an albatross colony on a Hawaiian island with an excessive number of females, the females would pair up annually to preen each other, join in ritual mating dances, and guard each other. Together they would hatch out a single egg each year, taking turns to sit on the nest. No male came near them after insemination.

  According to Frans de Waal, exclusive focus on members of the same sex, as shown among humans, is rare if not absent in the animal kingdom. I don’t agree with him. In Montana, Anne Perkins discovered that 10 percent of the rams intended for breeding weren’t mounting ewes. They were referred to as “lazy.” But out in the meadow they were anything but lazy, as they enthusiastically mounted other males. Some rams even took turns mounting each other. Perkins discovered chemical differences in the hypothalami of these rams that indicated altered interaction between hormones and brain cells. Structural differences were also found in the hypothalami of these homosexual rams just like the ones that we and other researchers described in the case of humans. Of course homosexuality is a natural variation.

  TRANSSEXUALITY

  Re: new phalloplasty technique proposal; seeking surgeon. P.S. I am interested in a neophallus uncircumcised in appearance. So I am looking overseas, since a natural uncircumcised penis is more common in Europe than in the U.S.

  From a letter to the author from an American female-to-male transsexual

  Transsexuals feel that they have been born into a body of the wrong gender and are desperate for a sex change or gender reassignment. This is a gradual process that starts with an individual adopting the social role of the opposite sex and taking hormones, then undergoing a series of extensive operations—which only 0.4 percent later regret. The first person in the Netherlands to respond to the plight of transsexuals was Otto de Vaal, an endocrinologist and pharmacologist who taught at the University of Amsterdam. He treated them for free starting in 1965, feeling that his university pay was sufficient. The gender team of the VU University Medical Center in Amsterdam (VUmc) subsequently took on a pioneering role, headed first by Louis Gooren and now by Peggy Cohen-Kettenis. That’s remarkable in itself because the Vrije Universiteit was established as a Calvinist university, and the Bible does say: “A woman shall not wear man’s clothing, nor shall a man put on a woman’s clothing; for whoever does these things is an abomination to the Lord your God” (Deuteronomy 22:5–6).

  Since 1975, 3,500 people have undergone gender reassignment at the VUmc. The first time I learned about transsexuality was as a medical student in the 1960s. Coen van Emde Boas, a professor of sexology, entered the lecture room of the obstetrics and gynecology department with a bearded man. It wasn’t exactly the place you would expect a man to be demonstrating anything. But he turned out to be a genetic woman, a female-to-male transsexual. This made a deep impression on me, and set me thinking about the possible underlying mechanism.

  Male-to-female transsexuality (MtF) occurs in 1 in 10,000 individuals, and female-to-male transsexuality (FtM) in 1 in 30,000. Gender problems tend to become apparent from an early age. Mothers typically relate how their little boys dressed up in their frocks and shoes, were only interested in girls’ toys, and mainly played with girls. But not all children with gender problems want to change sex later. If necessary, puberty can be delayed with the help of hormones to gain extra time in which to decide whether or not to undergo treatment.

  All the data indicates that gender problems arise in the womb. Tiny variations in genes associated with the effect of hormones on brain development have been found to increase the likelihood of transsexuality. It can also be increased by abnormal fetal hormone levels or by medication taken during pregnancy that inhibits the breakdown of sex hormones. The differentiation of our sex organs takes place in the first months of pregnancy, while the sexual differentiation of the brain occurs in the second half of pregnancy. Since these two processes take place at different times, the theory is that in the case of transsexuality, they have been influenced independently of one another. If this is the case, one would expect to find female structures in the brains of MtF transsexuals and vice versa in the case of FtM transsexuals. In 1995 we indeed found, in postmortem studies of donor brains, a small structure in which the usual sex difference was reversed. We published our findings in Nature. The brain structure in question is the bed nucleus of the stria terminalis (BST), an area that’s involved in many aspects of sexual behavior (figs. 10 and 11). The central part of this nucleus, the BSTc, is twice as large in men as in women and contains twice as many neurons. We found MtF transsexuals to have a “female” BSTc. The only FtM transsexual we could study—the material in question being yet rarer than the brains of MtF transsexuals—indeed proved to have a “male” BSTc. We were able to rule out the reversal of the sex difference in transsexuals being caused by altered hormone levels in adulthood, so the reversal must have happened at the developmental stage.

  If you publish something truly interesting, the nicest thing you’ll probably hear your colleagues say is, “It’ll need to be confirmed by an independent research group.” And that can take a while, because it took me twenty years to collect the brain material for my study. So I was delighted when in 2008 the group headed by Ivanka Savic in Stockholm published a study involving functional brain scans of living MtF transsexuals. They had not yet been operated on, nor given hormones. As a stimulus they were given male and female pheromones, scents that aren’t consciously perceived. In control groups, these were shown to produce different patterns of stimulation in the hypothalamus and other brain areas in men and women. The stimulation pattern for MtF transsexuals fell between that of men and women.

  In 2007 V. S. Ramachandran published an interesting hypothesis and provisional research findings on transsexuality. He believes that the neural body map of MtF transsexuals lacks a penis, while that of FtM transsexuals lacks breasts, due to these not being programmed into the map during development. As a result, they don’t recognize these organs as their own and want to get rid of them. So everything indicates that the early development of sexual differentiation in the brains of transsexuals is atypical and that they aren’t, in fact, simply psychotic, as a Dutch psychiatrist was impertinent enough to claim recently. At the same time it is o
f course essential, before initiating treatment, to make sure that the desire to change sex isn’t part of a psychosis, as it can be an occasional symptom of schizophrenia, bipolar depressions, and serious personality disorders.

  FIGURE 10. Located at the tip of the lateral ventricle (1) is the bed nucleus of the stria terminalis (BST), a region of the brain important for sexual behavior.

  FIGURE 11. The central part of the bed nucleus of the stria terminalis (BSTc) (see fig. 10 for location) is twice as big in men (A, C) and contains twice as many neurons as in women (B). In male-to-female transsexuals we found a female BSTc (D). The only female-to-male transsexual we could study (these brains being rarer than those of MtF transsexuals) indeed proved to have a male BSTc. This reversal of the sex difference in transsexuals corresponds with their gender identity (the feeling of being a man or woman) rather than with their chromosomal sex, or the sex on their birth certificate. LV = lateral ventricle, BSTm = medial section of the BST. J-N Zhou et al., Nature 378 (1995): 68–70.

  PEDOPHILIA

  “May I humbly crave Your Excellency’s permission to be castrated?”

  The shocking scale of child abuse within the Catholic Church has come to light in recent years. The first cases emerged in the United States, then in Ireland, where, within the bishopric of Dublin alone, hundreds of children were abused between 1976 and 2004. Cases in Germany were subsequently exposed, after which hundreds of victims came forward in the Netherlands. These revelations show that, as a result of the taboo surrounding pedophilia, we have no idea how frequently such abuse actually occurs—not just in the church but in general.