Is a person's gender determined by the brain?

Is a person's gender determined by the brain?
Is a person's gender determined by the brain?

Scientists answer this question in the affirmative. They see differences both in brain size and in our behavior. A psychology professor at the Karolinska Institute in Stockholm believes there are very few behavioral domains where there are no such differences. So do innate differences play a role?

What does science say about the potential differences between women and men?

“In fact, I would say that there are very few behavioral areas where there are no such differences. Even if these differences are often very small,”says Agneta Herlitz, professor of psychology at the Department of Clinical Neurology at the Karolinska Institute in Stockholm.

But if the differences are small, this does not mean that they do not matter.

“It can be small differences in basic functions that affect our behavior and therefore can be of great importance in our daily life. Differences can be seen in terms of aggression, memory, sexual behavior, personality, perception, motivation, self-esteem and so on."

There are differences at the group level, that is, the average man differs from the average woman. But the differences within both groups are almost always much greater than the differences between the groups themselves as a whole. Men, on average, have better spatial thinking than women, that is, they can better imagine how three-dimensional objects look, and what they will turn out to be if you turn them in different directions - this ability can be used when, for example, you assemble a nightstand from IKEA. But the level of this ability can differ much more between the two women than between women and men on average. In addition, many women have better spatial thinking than many men. That is, one cannot draw conclusions about how well a person assembles furniture, starting only from his floor.

Nevertheless, studying the differences between the sexes is still important, says Agneta Herlitz.

“Most people have some ideas about this - we are convinced of this and that. But it is not good to hold on to prejudices and ideas about something without having a clue of what is really true. In many cases, it is quite realistic to find out how things are in reality. That is why we are studying this issue,”she says.

Behavioral differences have been studied in many countries around the world.

“The same models were found everywhere. The magnitude - that is, the degree - of differences may differ from country to country, but their nature is almost always similar. Most often, we see these differences throughout the life of people, and not only in certain age groups, otherwise it could be associated rather with our way of life."

Studying the brain for sex differences can be important for medical reasons. Women are more likely to suffer from Alzheimer's disease and depression, while men are more likely to be diagnosed with autism spectrum disorders, schizophrenia and dyslexia. If we better understand how our brains work, we can find more effective treatments.

One of the biggest differences between male and female brains has to do with size.

“There is a huge difference. We have never found such behavioral differences,”says Agneta Herlitz.

The difference persists, but becomes less significant when it is taken into account that men are, on average, taller and heavier than women.

One of the largest studies on the differences between the brains of men and women was published in 2018 in the Cerebral Cortex. It used data from the British Biobank, including analyzes of volunteers 40 and older. The team compared MRI images of the brains of 2,750 women and 2,466 men between the ages of 44 and 77. As in past studies, scientists have found that men's brains are, on average, larger in volume and area, while the cerebral cortex - its topmost layer - is, on average, thicker in women.

“Actually, there is nothing new in this. But the good thing about this study is that a lot of people took part in it, and their brains were studied in very different ways,”says Agneta Herlitz.

In almost all the indicators that scientists studied, the spread was greater in men than in women. This means that between men with the largest and smallest brains, the difference was greater than among similar women. One possible explanation is that the two x chromosomes in women offer some kind of protection against mutations. If something is wrong with one, the other takes over her responsibilities.

Some of the differences between internal parts of the brain, such as the hippocampus, disappeared when scientists took into account that men have more total brain volume.

“The hippocampus is involved in memory-related processes. If they don't see the difference between men and women, it means that women have a relatively large part of the brain in the hippocampus,”says Agneta Herlitz.

Agneta Herlitz is studying the so-called verbal episodic memory, which, on average, is better in women than in men.

“It's about how well you remember what happened yesterday, how easy it is to learn and remember what you already learned,” she says.

All of this is of great importance in our daily life.

"We remember who we met, what we did, who said what at the meeting, we keep different things in our mind."

Several years ago, Agneta Herlitz and her colleague Sergei Degtyar published a study in Intelligence in which they compared 168,000 16-year-old Swedes' grades in Swedish, English, mathematics and technical sciences with what they ended up in at the age of 32 years. Higher marks in English and Swedish were more often among girls, and in other subjects - among boys. Most of them chose further education according to their academic talents. But women who had good grades in math and technical subjects were still not inclined to choose the appropriate professions and education in the same way as men with the same academic talents.

Gender-specific differences in talent and school achievement can only partly explain gender distribution in college and professional life, the study says.

“We can say that we are missing out on some women who could work in technical industries,” says Agneta Herlitz.

So do innate differences play a role?

“It goes without saying that the differences can depend on both biology and the environment. But the difference is not the problem. The problem is how we assess the differences. Why are masculine qualities ranked higher when measured by salary and influence?

Also, we must not exaggerate the real differences. Equality is the freedom for everyone to do what you want and choose what you want, without being gender-based or suffering from the feeling that you have been forced to prefer something worse than what you can get."

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