by D. F. Swaab
Nowadays, articles on the differences between male and female or heterosexual and homosexual brains barely cause a ripple (see for instance Swaab, D. F., Proc. Natl. Acad. Sci. USA 105 [2008]: 10273–74), and there’s a great interest in the topic in popular science publications.
CHECKING THE POPE’S SEX
At the stage when our bodies and brains differentiate along male or female lines, hybrid forms sometimes develop. This can have far-reaching consequences. A controversial example of hybrid sexuality dates back to the Middle Ages, when a woman allegedly became pope, subverting the strict male hierarchy of the Roman Catholic Church. Measures are said to have been taken to prevent such a “disaster” from occurring again.
The story of Pope Joan was chronicled by the Dominican monk Jean de Mailly around 1250, and a film was made of it in 1972. Was it a myth or a cover-up? No one knows for sure. The gist of the legend is as follows. Though born in the German town of Mainz in 833, Joan was of English extraction. Having traversed Europe dressed as a monk, she gained so much respect and authority for her great learning that she succeeded Leo IV as pope in 854, taking the name of Johannes Anglicus (John the Englishman) or John VIII. Three years later, however, she became pregnant, suddenly giving birth during the Easter procession, near the Basilica of San Clemente in Rome. This gave the game away, of course, and she was lynched on the spot. Her successor, Benedict III, is said to have eradicated all trace of her memory. There’s no record of Joan in the Vatican’s pontifical yearbook.
Although the Catholic Church systematically denies the story, there are indications that there may be some truth in it. In 1276, Pope John XX was said to have changed his name to John XXI in order to account for the female Pope John. What’s more, records indicate that the sculpted head of John VIII, “Femina de Anglica,” stood alongside the busts of all the other popes in the Cathedral of Siena. In 1600, however, her bust was removed by order of Pope Clement VIII.
And then there’s the chair with the hole, referred to in Italian as La Sedia Gestatoria—meaning “litter” or “sedan chair.” But why would a sedan chair have a hole in the seat? The story goes that, to prevent another female pope from being elected, candidates for the papacy were required to sit on the chair. The youngest cleric present had to stick his hand through the hole, feel the papal candidate’s genitals, and then call out loudly, “Testiculos habet et bene pendentes” (“He has testicles and they hang well”). The cardinals present would then respond, “Habe ova nostra Papa” (“Our father has balls”—as if they were any use to him). The need for such testing suggests that the story of Pope Joan may very well be true. Maria New, a New York pediatric endocrinologist, has put forward the theory that Pope Joan had a form of intersex called congenital adrenal hyperplasia, or CAH (see earlier in this chapter). But this diagnosis is pure speculation.
In her article (1993), New referred to a red marble chair that apparently stood in the Vatican Museum. When I met Dr. New in 2007 at a conference in Rome, however, I asked where exactly the chair was, because I’d been invited to the Vatican the following morning. She told me that she had never gotten to see it. The one depicted in her article had been an identical chair looted by Napoleon, now in the Louvre, to which she had only gained access after negotiating a great deal of red tape.
At the Vatican the next day, on a private tour organized by one of the pope’s doctors, a collaborator of mine immediately said to the head of security that I was especially interested in seeing the chair. No problem, our security man responded, though he immediately added that Maria New’s theory was nonsense. According to him, the chair was simply an ancient commode. At the time I wondered how he knew about her article. It was highly technical and published in an academic journal intended for specialists—not the kind of reading you associate with security guards.
He gave us a tour through the hushed corridors of the Vatican. We saw the room where the cardinals elect the pope, the “crying room” to which newly appointed popes are ushered to shed a few tears, the containers of white and black smoke, the chamber with the famous balcony where the pope appears (and from which Pope John Paul II called out in something faintly resembling Dutch, “Thanks for the flowers!”), the terrible murals everywhere, and the Swiss guards flanking each important doorway. We were shown the papal gardens, the secret escape route to the stronghold, and so on. Our guide even got out all the pope’s gorgeously embroidered mantles for special occasions so that we could admire and feel them. One was pink. “Is that for Saturday evenings?” I asked the cleric, who was lovingly displaying each garment. “No,” he answered seriously, “that’s for prison visits.” The pope’s miters were unpacked for us, along with a crucifix that he takes with him on his travels—there was no end to it all.
It was all most impressive and yet not quite what we’d come for, and I reminded our guide of the chair. Yes, yes, it was a bit farther on, he said soothingly. When we had emerged from the silence of the private rooms, had passed the Sistine Chapel with its hordes of tourists, and had gone once again through a series of doors opened and locked behind us by Swiss guards, I mentioned the chair once more.
“Oh, what a pity,” said the head of security. “We passed it about fifteen minutes ago. I’m so sorry, I completely forgot about it.”
“No problem,” I said airily, “we can just go back.”
Alas, this was impossible, “for security reasons,” the security officer said, as he told us exactly which country had donated each of the many trees and shrubs in the Vatican garden. A complex network of cables hung over our heads, and large antennas betrayed an advanced communications system. The way back to the Middle Ages had been cut off. So that ended my chance to establish the truth of the chair and Pope Joan, but the matter continued to preoccupy me. If the chair didn’t exist, why didn’t the security officer just say so? Why did he keep stringing us along? Was the chair still being used, or might Pope Benedict XVI have been toying with the idea of reinstating this old custom?
4
Puberty, Love, and Sexual Behavior
THE ADOLESCENT BRAIN
Puberty starts with a kiss.
Dungan et al., 2006
In puberty, the pituitary gland starts to produce sex hormones. These affect the adolescent brain, causing marked and often incredibly annoying behavioral changes. The evolutionary advantage of puberty is clear: Youngsters are being prepared for reproduction. And their annoying behavior, leading to frequent clashes with their families, makes it less likely that reproduction will take place in their own surroundings, thus reducing the risk of inherited defects. The craving for new experiences, the readiness to take great risks, and the impulsive behavior are all part of preparations to leave the nest. Because their prefrontal cortex hasn’t yet matured, adolescents can think only in the short term and are unable to take in the negative consequences of risky choices. As a result, they are also more likely to try addictive substances that can permanently damage the developing brain.
A great many chemical changes are needed to initiate puberty. Its onset is triggered by the gene KISS1, which produces the protein kisspeptins in the hypothalamus. The gene is so central to this process that it has been said that “puberty starts with a kiss.” The gene was discovered by American researchers in Hershey, Pennsylvania, and named after the most famous local product, the Hershey Chocolate Kiss. People with a mutation in the KISS1 system never enter puberty.
However, puberty is dependent on other systems, too. For instance, women must have sufficient fat reserves to be able to nourish a fetus at times of scarcity. Before puberty, the brain registers whether there’s sufficient fatty tissue by monitoring the amount of leptin, a hormone that’s produced by fat cells. If the fat reserves are insufficient—because of an eating disorder, for instance, or intense athletic training—leptin levels decline and puberty is delayed, sometimes for good. Similarly, mutations in the leptin gene can impede puberty and also cause extreme obesity. In such cases, the brain registers the absence of
leptin—and therefore of fat. The brain then blocks the onset of puberty because pregnancy would be too risky while also sending out a signal to eat copiously to make up fat reserves—unaware that it’s merely leptin, not fat, that’s lacking.
Melatonin, a hormone produced by the pineal gland, is one of the substances that prevent the onset of puberty in children. Melatonin’s inhibiting effect has been known since 1898, when Otto Heubner described a boy of four and a half who had already entered puberty. He turned out to have a brain tumor that had destroyed his pineal gland, which resulted in a lack of melatonin, in turn spurring the onset of puberty. A Dutch girl who started puberty at the age of three and a half was more fortunate. She didn’t have a brain tumor and was given inhibitory hormones up to the age of twelve. Then she entered puberty again and is now flourishing at secondary school. Conversely, some people’s melatonin level is too high and has to be normalized before puberty can start.
Puberty can also be disrupted by a condition known as Kallmann syndrome. Normally, the brain cells that stimulate the sex hormones develop at the place where a fetus’s nose develops. The cells then migrate along the olfactory nerve to the hypothalamus. This process is disrupted in patients with Kallmann syndrome, so that not only do they not enter puberty, they also lack a sense of smell.
So we should stop dismissing the embryonic and adolescent brains as organs in which not much is going on yet. On the contrary, they are both undergoing the most complex and delicate modifications.
ADOLESCENT BEHAVIOR
Young people today love luxury, they have bad manners, contempt for authority and disrespect for older people. They’re too lazy to train; they’d rather sit and chat.… They no longer rise when elders enter the room, they contradict their parents, can’t hold their tongues in company, gobble their food, and tyrannize their teachers.
Socrates
According to adolescents, it’s not their immature brains that are the problem, it’s their parents. In fact, they are more or less the same thing: A youngster’s parents function as his or her temporary prefrontal cortex (PFC, fig. 15). While the adolescent PFC is still immature, parents have to be responsible for a child’s planning, organization, moral framework, and limits. These functions are gradually taken over by the slowly maturing PFC. The problem is that today’s youngsters have discovered that their parents aren’t in a position to enforce their role as human PFC substitutes.
The PFC plays a central role in regulating other brain areas and is responsible, among other things, for the control of our impulses, complex actions, planning, and organization. It doesn’t fully mature until a person is in his or her twenties. According to the neuropsychologist Jelle Jolles, this explains why a recent restructuring of the Dutch secondary school system that focused on independent study is flawed. When your PFC hasn’t matured, you’re not very good at organizing your work and making independent choices. Functional scans also show clear differences between the brains of adolescents and those of adults. Adults distribute assignments across different brain areas. Adolescent PFCs can sometimes function at an adult level but need to work much harder to do so, as they fail to outsource tasks to other brain areas. As a result, a teenager’s PFC reaches the ceiling of its capacity earlier, and distractions can undermine the performance of assigned tasks.
The regulation of day-night rhythms is also influenced by sex hormones. That might explain why it’s so hard to get adolescents out of bed in the morning and into it at night. Should we force them to get up early or adapt school hours to their biological clocks?
A lot of drinking goes on in puberty: At the age of fifteen, 52 percent of boys and 46 percent of girls in the Netherlands drink at least five units of alcohol an evening on the weekend, and children of that age regularly end up in a coma in intensive care. The practice of “pre-gaming” before going to parties is now quite common. Alcohol abuse makes the brain shrink, causing permanent damage. In Europe, around fifty-five thousand youngsters die annually of alcohol poisoning or in traffic accidents in which alcohol was involved.
The sudden surge of sex hormones during puberty causes not only sexual awakening but also typical male aggression and risk-seeking behavior. That explains why the incidence of unrestrained, antisocial, aggressive, and delinquent behavior increases during puberty. A survey in the Netherlands showed that one in three children between the ages of ten and seventeen commits a crime, ranging from theft and breaking and entering to vandalism and crimes of violence. After the age of seventeen, young people commit fewer crimes. It seems logical to assume that this curve reflects the gradual development of the PFC, which inhibits impulsiveness and promotes moral behavior. Parents can take comfort in the thought that puberty is a finite process. Teachers, on the other hand, must sometimes despair. As fast as they mold adolescents and launch them into society, a fresh crop of impulsive youngsters enters the school gates. For teachers the process is never over.
THE BRAIN IN LOVE
LOVE, n. A temporary insanity curable by marriage.
Ambrose Bierce (1842–c. 1914)
A great many brain processes are involved in various stages of our love lives, including falling in love, sexual arousal, attachment leading to long-term partner bonding, and maternal and paternal behavior (see chapter 1). Although it wasn’t Mother Nature’s “intention,” we see on a daily basis that these stages can perfectly well exist independently of one another, and I will therefore look at them separately.
FIGURE 15. The prefrontal cortex (PFC) as seen from the side (external view at top, cross section at bottom).
No one who can still remember the suddenness and intensity of falling passionately in love will classify partner choice as a free choice or even a well-considered decision. Love at first sight just happens—it is pure biology—along with all the euphoria and severe physical reactions that ensue, like a beating heart; perspiration and insomnia; emotional dependency; strongly focused attention; an obsessive, possessive, and protective attitude toward the partner; and a feeling of heightened energy. Plato (427–347 B.C.) was equally convinced of the autonomy of this process. He regarded the sexual impulse as a fourth species of soul, located below the navel, describing it as “rebellious and masterful, like an animal disobedient to reason.”
For people all over the world, falling in love tends to be the basis for pair forming. You might think that where something as important as choosing someone to start a family with is concerned, our cerebral cortex would select the right person on a fully conscious basis. But no, during severe infatuation, when all of our attention and energy is focused on that one other person, it’s the areas down at the base of the brain, in structures that steer unconscious processes, that call the shots.
Brain scans of people who had just fallen deeply in love and who were shown a photograph of their significant other showed activity exclusively in brain structures below the cerebral cortex. Their reward circuitry was particularly active. This part of the brain focuses on obtaining a reward (in this case, for finding a partner) in the form of a pleasurable sensation, which is transmitted by the chemical messenger dopamine (fig. 16). The reward system isn’t involved just in matters of the heart but in everything that we find pleasant. It’s also associated with addiction, which explains why people experience severe withdrawal symptoms when a love affair ends. Scans show this system to be primarily activated on the right side of the brain, in proportion to the attractiveness of the face in the photo and the intensity of the romantic passion.
People who are in love also have raised levels of the stress hormone cortisol. Being in love is a stressful situation, and the body responds by producing more of this hormone. The level of testosterone (also produced by the activated adrenal gland) increases in women who are in love, while in men, cortisol reduces the testicular production of testosterone.
It’s only when love has persisted for a certain length of time that the prefrontal cortex, the front part of the brain involved in planning, deliberation, and assessm
ent, becomes involved. If stable pair formation ensues, the activity in the stress axis dies down and testosterone levels return to normal. The processing of sensory information in the cerebral cortex has of course played a role during that exciting period—we have, after all, seen, smelt, and touched the person we love. But this isn’t the same thing as making a conscious choice for that particular person. Whether they are “Mr. (or Ms.) Right” is determined by our ancient reward circuitry, which thus links reproduction to the “right” partner—or at least the right partner in that moment. Only when the most intense period of infatuation has passed does the cerebral cortex take over. So if your son or daughter suddenly falls for the wrong person, it’s no good reproaching them that they should have used their brains. They did, in fact, do so, but those parts of the cerebral cortex (such as the PFC) that could have come to a different decision after a balanced, conscious judgment unfortunately only kick in when it’s too late.
FIGURE 16. The dopaminergic reward system, originating in the cell bodies in the ventral tegmental area (1), whose fibers extend into regions including the ventral striatum (ventral pallidum/nucleus accumbens [2]), the caudate nucleus (3), and the prefrontal cortex (4).