Why do young men act so aggressively

The man's brain

The image of the strong sex

There is no arguing about the physiological differences: On average, men are not only ten centimeters taller and correspondingly heavier than women, they also have more developed muscles, are more capable of top athletic performance - and they have a larger brain.

It becomes more difficult when asked whether this male brain functions differently than the female one. On average, men should have a better spatial imagination (and therefore be able to park better) and be the more talented mathematicians.

On the other hand, they are also considered more aggressive and competitive and - what women have always known: men always think only about sex, tend to be infidelity and consider true feelings to be weakness, according to the stereotype.

Such clichés persist. Even if this does not apply to all men, it can be said that men are different from women in many ways. But what's behind that?

It's all a matter of genes, it is often said as an explanation, and the Stone Age model is gratefully used. The man, the hunter. He kills the prey, sometimes at the risk of his life, and provides the family with meat. He has been prepared for this task since time immemorial and throws himself into danger and into hostile life.

The woman, on the other hand, looks after the offspring, does light, filigree work with the other women and, if necessary, goes out of the cave to pick berries. After all, this role model seems to be so stable that it has lasted over the generations over the millennia.

A look at the classic 1950s family may confirm that. However, this classic role model has changed tremendously in our society.

So the question remains whether it is really the "selfish genes" that program men for maximum reproductive success, as some evolutionary biologists believe. Or isn't it the environment and culture that shape people - and thus men - and make them what they are in the end?

This "nature-versus-nurture-debate" was conducted with devotion in the 20th century. But whatever influence the biological and sociological conditions exert, today's man is in a difficult position.

Because the image of what and how a "real man" should be is no longer so clearly defined in society. He has to go on a search and find his roles anew.

It's not a question of genes

The fronts in this debate, in which some blame genetic predispositions and others the environment for human differences, have at least been softened by today's knowledge. A 2020 study by U.S. researchers suggests the answer lies between the two fronts. The scientists examined the brain scans of almost 1,000 men and women and found that some regions of the brain are quite different.

In women, the researchers discovered more gray matter in the prefrontal cortex in the forehead area, in the overlying orbitofrontal cortex and in parts of the parietal and temporal brain. These regions are responsible for controlling tasks and impulses and for dealing with conflicts. Men, on the other hand, have more volume in the posterior and lateral areas of the cortex, which are responsible for recognizing and processing objects and faces.

The researchers concluded that it is not just environmental conditions that can lead to the gender-specific differences. They are at least in part innate. Many other studies have approached the question of whether there is a difference between the sexes, above all the decoding of the human genome.

In the course of this, it has been shown that nothing has changed in the human genome for at least 100,000 years. So our Stone Age ancestors had the same genetic makeup as we have today. That means: Even then, they had the same potential as the basis for the development of a brain. But what has changed then?

The basic knowledge comes from modern brain research: the brain always develops in the way that it is used and how it is needed. How much has changed in today's living conditions compared to those of our Stone Age ancestors is easy to see.

The high-tech digital age, in which humans fly, drive cars and surf the Internet, is leaving its mark - also in our brains. But why do men then think, feel and act so differently from women? How big is the influence of genes when it comes to the difference between the sexes?

After all, men go into life with a different genetic makeup. Instead of a second X chromosome, they have a Y chromosome. "There is no gene that is responsible for the fact that men look very different and often think, feel and act very differently from women," says Gerald Hüther, brain researcher and professor emeritus for neurobiologist at the University of Göttingen.

In short: on this Y chromosome there is not a single building instruction for how a male brain is to be structured. But not only the brain structures and the networking of nerve cells, but our body characteristics are determined by genes that are on the 45 chromosomes that both sexes have.

Nevertheless, this small Y chromosome has the main driving force behind the different development of the two sexes: It is responsible for the typical male testosterone production. This hormone is the small difference with the big impact.

Testosterone is not only responsible for the development of primary and secondary sexual characteristics. It also ensures that the other body characteristics such as muscle mass, stature and skeletal structure acquire "masculine features". Even the way in which the neural network of the male brain interconnects is influenced by testosterone.

The hormone makes the man

Brain researcher Gerald Hüther is certain that men would develop differently even if they had exactly the same environment. You cannot escape the influence of testosterone, which affects the male fetus from around the tenth week in the womb.

It is thanks to this prenatal influence of the male sex hormone that boys are born with a slightly differently organized and structured brain than girls.

Hüther compares the brain to an orchestra. As far as the line-up is concerned, the same instruments are used for men and women. The hormonal equipment, however, means that men have more timpani and trumpets in the first row, while women tend to use instruments that carry harmony in these seats.

That also means: boys make a different kind of music right from the start. Correspondingly, with their different orchestral structure, they can do some things better and some less well than girls.

Our brain is designed the way it is used

Brain research has shown that our brain is a lifelong construction site. It always reacts to signals from within - our hormones belong to them - and from outside.

The brain networks, thinks and works the way it is used. "It's like building a house," explains Gerald Hüther: Boys and girls have, so to speak, a differently structured foundation, even though the same materials were used. There are different requirements for the further expansion and extension of the house. Accordingly, the building will continue to be different and the house will have a different shape.

To stay in this picture, the hormones are a potential that influences brain development, i.e. the foundation. The environment into which we are born corresponds to a potential that influences further expansion. However, this potential environment is so rich that it is impossible to use all of it.

So we have to choose something from it; of course we choose what is important to us and what seems important to us. This different, hormonal "foundation" becomes noticeable very early on. Even as babies, boys are enthusiastic about other things - and are usually more outward-looking than girls.

What exactly is going on up there in the brain? "When you do, think or perceive things that are important for your own life, deeper emotional centers in the brain are aroused," says brain researcher Gerald Hüther. This strengthens and consolidates the activated neural connections and synaptic connections.

For example, those who like to swing a tennis racket, love to interact with animals, are enthusiastic about an instrument or enjoy foreign languages, will usually do so more often. The brain adapts to this "repeated use" by creating and expanding the appropriate new interconnections.

If the nerve tracts that are activated in the brain are initially quite tender, they become stronger and stronger with increasing use, similar to a muscle, and develop into roads that are more and more easily activated and "drivable". "The brain changes and then you have a different brain than before," summarizes Hüther.

But that also means that it is not the environment that is responsible for ensuring that a brain develops this way and not differently, but one's own enthusiasm. This enthusiasm is the mainspring according to which criteria every person chooses the aspects of his environment at any time and in any place. The result is a neural road map that differs not only in general from person to person, but also in particular between men and women.