Men and women are so different because their brains are different. This is the common myth. In fact, there are almost no differences. Scientists come across only one thing over and over again.
Women are interested in people, and men are interested in things. Women seek empathy, men prefer systematization. Of course, because the brains of men and women are completely different. Women's brains are better supplied with blood. But men are heavier. Women have more gray matter, men have more white. Supposed differences like these are abundant on the internet, but scientifically questionable. Because it is not at all clear what effect these differences have on functionality.
The myth that the male brain looks and functions completely differently than the female brain is firmly entrenched. That said, the differences are usually very minor, the researchers say. And it is unclear if these minimal differences are in any way related to behavior or specific abilities. Differences are found only in one area of the brain; here the difference is really not just great. Scientists are also sure that it is she who is actually reflected in the behavior of women and men.
The part of the brain in question is only a few millimeters long. It is located deep in the brain, in an evolutionarily very old region, the diencephalon. Its functions are for the most part so basic, so instinctive, that it is hardly more complex in humans than in other mammals. And there is the so-called Nucleus präopticus medialis: a small nucleus of nerve cells, that is, a group of nerve cells that together perform certain tasks.
Differences are laid in the womb
This area of the brain belongs to the human sex center. In male mammals, it is the nodal point that is responsible for the "typically male" behavior: dominance, aggressiveness and sex drive. Women, on the other hand, do not have a single center of control. Their dominance, aggressiveness and libido are separated and controlled by different nerve centers in the diencephalon.
Since this special function in men is performed by the Nucleus präopticus medialis, its size is more than twice the size of a woman's. Therefore, the large cell nucleus is the only part of the brain from which researchers can confidently determine whether the brain belongs to a man or a woman.
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And already at a fairly early stage. By the beginning of the third month of pregnancy, the fetus develops its germ cells: the ovaries in girls and the testes in boys. The Y chromosome of a male embryo communicates through neurotransmitters to the mother's brain that she needs testosterone to develop into a boy, and builds a receptor binding site for the hormone stimulus. In addition, in the amygdala of the cerebellum, which processes emotional impressions and where, as a result, sexual and aggressive behavior arises.
“Today hardly anyone else doubts that this prenatal difference between men and women has a definite effect on behavior,” says Gerhard Roth, who is a neuroscience and behavioral psychologist at the University of Bremen.
There is a lot of scientific evidence
There is evidence that the Nucleus präopticus medialis is indeed responsible for "typically male" behavior. For example, scientists transplanted male relatives of Nucleus präopticus medialis into female rats. After that, the rat began to climb onto other females. She also became more aggressive than before and took part in battles for territory.
Among people, there are also indications of how significant the nerve nucleus is for the behavior of the sexes. When men or women feel sexually attracted to people of the same sex. Even at the stage of fetal formation, homosexual men have significantly less Nucleus präopticus medialis than their heterosexual sex mates.
The opposite is true for lesbian women. They have a larger nerve nucleus than heterosexual women. In certain cases, this can lead to the fact that the genetic sex no longer matches the hormonal one. Then they talk about intersexuality.
Scientists suggest that in this case, there was a violation of communication between the embryo and the mother's hormonal system. This manifests itself in a more or less pronounced form for more than 5% of pregnancies.
The stress hormone cortisol also plays a role
Brain researcher Roth concludes from previous research that hormonal relationships are primarily responsible for differences in behavior between the sexes. This is confirmed by the results of behavioral research. For example, it is known that women react to stress more strongly than men, and are usually more fearful and anxious than men.
Stress is closely related to the hormone cortisol: high cortisol levels increase fear of pain and danger. Women in the brain do not have a special nucleus of neuroticism in the brain. But there is a hormonal cycle that could easily explain why women are more nervous than men.
This is because testosterone suppresses the stress hormone cortisol. Since women, on average, have less testosterone circulating in their brains, their stress hormone can work unhindered. In men, at times saturated with testosterone, the effect of cortisol decreases.
Since these hormonal differences are established before birth, they are likely to influence how behavior develops. For example, brain researcher Roth suggests that boys develop better spatial intelligence over the course of their lives because they are hormonally tuned in to explore and discover. They climb, build and try new things.
Only the mean values differ significantly
Girls are more cautious because of their higher cortisol levels. They often choose to stay with people they know. And so they learn to communicate with others early. So, on average, one can explain the best verbal abilities without claiming a particularly good language center of the female brain.
If that were the case, Roth explains, we could see distinct differences in the area of the cerebral cortex. In the part of the brain where all the zones that turn us into intelligent beings are located, where language, logical thinking and complex feelings arise.
Certain hormonal prerequisites can contribute to the fact that women prefer to work with people, and men - with things. But the qualities that children develop during their life depend more on upbringing. And this does not contradict the fact that Emma will become an excellent engineer, and Lucas - a favorite teacher at school.
Finally, when discussing gender differences, we are always talking about averages only. A person's testosterone levels can vary significantly. So little Emma can happily run and climb or knock over her judo partner. Lucas might be better off playing board games with his neighbor's boy better than playing a ball in the garden.
Mareike König
