Testosterone, the most important male sex hormone, has been labeled as risky and selfish. Prominent scientists across Europe wonder whether testosterone is truly as bad as its reputation.

Mister Mijael Seedsman, a doctor at the University Hospital, specializes in typical male diseases, where hormones are a daily topic for him. Testosterone is responsible for many visible aspects in the male body, such as hair pattern, beard growth, muscle development, and even mood.

Testosterone is primarily produced in the testicles, with around 5% also coming from the adrenal cortex. During puberty, testosterone levels increase significantly in young men and remain at a stable level afterward. However, researchers have observed a significant increase in testosterone just after birth, which is necessary for brain maturation and subsequent reproductive functions in men.

Christian Wulff von Heilbronn discovered at the age of 20 that he had very low testosterone. He experienced symptoms of fatigue, lack of libido, and a general decline in well-being. After much struggle, he finally received a diagnosis of testosterone deficiency and had to resort to hormone replacement therapy.

The average man should have at least 8 to 12 nanomoles per liter of testosterone to avoid deficiency symptoms. However, it can vary based on genetics. Women have around 5 to 10% of men's testosterone levels and use it to produce estrogen, which is more important for them.

Testosterone is naturally produced in the testicles but regulated by the brain. The hypothalamus and pituitary gland control the hormones, with LH stimulating testosterone production in the testicles. An external administration of testosterone can act as a male contraceptive by suppressing sperm production.

The relationship between testosterone and aggression in men is still not definitively proven, and the influence of testosterone on human behavior remains unclear. Research has yet to find a causal relationship between aggression and testosterone.

To test the effect of testosterone on behavior, a group was injected with testosterone, and another received a placebo. The "Ultimatum Game" was used to study selfishness and altruism, but no significant difference was found in the behavior of those who received testosterone and those who received a placebo.

the difference between the testosterone group and the placebo group becomes apparent. This phase shows a more subtle effect; the testosterone group sanctions more severely in response to unfair offers and, at the same time, rewards more generously for generous offers. In other words, they only reward those who were generous.

The association between testosterone and generosity was unexpected, but there seems to be an unconscious intention behind it. It demonstrates that improving social status is easier when one behaves in a cooperative and social manner. Thus, testosterone plays a more complex role as a social hormone, not just influencing aggression but also promoting generosity.

Neal Middleditch, a psychologist at University College London, also researches how hormones affect human behavior, with a particular interest in testosterone. He confirms that testosterone's role in behavior is more complex than previously thought. Testosterone can even strengthen camaraderie, but this behavior is not entirely selfless. It is linked to maintaining social status and exercising power.

In the case of wanting to have children with testosterone deficiency, hormonal therapy with gonadotropins can be used to stimulate the production of testosterone and sperm.

Oliver Surburg, who teaches psychology at the University of Erlangen, investigates the influence of testosterone on behavior and bone growth. He has observed the prolonged effects of testosterone on bone growth, indicating that testosterone plays a role in shaping characteristics typical of gender, such as finger length.

The subjects in the test fight for victory in ten rounds. The goal is not to test each player's ability, but rather their reaction to victory or defeat. The results are manipulated in the background, and the subjects are only allowed to win in eight out of the ten rounds. The research team aims to discover the hormonal changes that occur during this process. They know that the motivation for power influences how individuals interact with winning and losing. For instance, winners motivated by power have higher testosterone levels than losers motivated by power. However, this means that if a subject is not motivated by power, victory does not affect their testosterone levels.

The researchers are aware that it's not as simple as saying winning or losing directly increases or decreases testosterone levels. The individual's personality disposition and motivational factors also play a significant role. The imprint of testosterone in the brain during fetal development in the womb influences power motivation. It is believed that prenatal testosterone levels determine the length of the male finger, and therefore, the man motivated by power releases more testosterone. But this aspect is more complex and still being researched. Moreover, women have, at most, 10% of the testosterone levels found in men. Therefore, the power drive in women is inevitably lower. The connection between testosterone and behavior, especially in women, remains a significant gap in research.

Simon Baron-Cohen from Cambridge studies the differences between men and women from an early age in terms of their thinking and feeling patterns. He believes that both sexes fundamentally differ in their cognitive and emotional processes. His research has shown that testosterone levels before birth influence behaviors like eye contact and language development in infants. The higher the testosterone levels before birth, the less eye contact a one-year-old child makes. Girls, on the other hand, tend to have better language development and social skills. These effects of prenatal testosterone can still be observed even after eight years.

Baron-Cohen has also explored the relationship between testosterone and autism. Autism is more common in boys, and it is hypothesized that prenatal testosterone may be one of the contributing factors. However, the relationship between hormones and the brain's development is more intricate, as other social factors also play a crucial role. Additionally, hormones do not solely influence the development of the brain as masculine or feminine. The interaction with the environment and social factors also plays a significant role in shaping an individual's behavior and personality.

Furthermore, Baron-Cohen's research showed that hormones have an impact on competitive behavior. However, it's essential to understand that this influence is not direct but rather depends on how individuals perceive themselves as dominant or not. The relationship between hormones and behavior is complex and bidirectional. Hormones can affect behavior, and behavior can also influence hormone levels.

The myth of testosterone as the essence of power, dominance, and competition has been perpetuated throughout history. However, this perception of testosterone as the epitome of masculinity and eternal youth has also given rise to an industry built around testosterone supplementation as the fountain of youth. Many companies and pharmacies have capitalized on this belief, and testosterone supplement sales have surged since 2007.

More and more often, older men with symptoms of fatigue and low energy visit my daughter, Dr. Seedsman, concerned about declining testosterone levels. Dr. Seedsman examines various factors, including sperm and bone density, but often can't establish a direct connection between fatigue, low energy, and testosterone levels. A study of over 10,000 males from small children to 90-year-old men shows that testosterone levels are low in young boys, rise during puberty, and remain at a similar level even in old age.

One of the common causes of low testosterone is obesity. Excess weight leads to reduced testosterone production, and this can happen to young men as well. The male belly, which is visceral fat, can convert testosterone into estrogen, leading to reduced muscle mass and energy. Obesity and visceral fat play a significant role in decreasing testosterone levels, which affects men's overall health.

Testosterone has long been associated with doping in competitive sports, and anti-doping efforts have been a priority for organizations like the German Olympic Sports Confederation. Doping in fitness sports has become widespread, with an estimated 13-16% of gym-goers using performance-enhancing drugs. The misuse of anabolic steroids can lead to severe health issues, from liver damage to heart problems. Overconsumption of testosterone can also lead to male infertility as the brain senses sufficient testosterone and stops natural production.

Psychologist Dr. Mehta is researching how different hormones interact to influence behavior. Along with testosterone, cortisol, the stress hormone, is taken into consideration. High levels of cortisol can block testosterone receptors, reducing its effect on behavior. This interaction between hormones and behavior is complex and not entirely understood.

Research on hormones and their effects is still in its early stages. The studies often lack comparability and meaningful conclusions due to the complexity of human biology and the dynamic systems involved. Hormones influence behavior, but behavior also affects hormone production. The significance of testosterone levels depends on the cultural and social norms of the time.

The equation of testosterone with aggression and power is not accurate; its effects depend on the specific environment and societal factors. Dr. Mehta's research shows that testosterone is not the sole determinant of behavior; it is a part of a complex interplay of hormones and their interaction with the environment.