- the concentration of androgens is responsible for the development of the genitals
- testosterone is associated with assertiveness, dominant and self-confident appearance and career orientation
Overview of topics:
Boy?, else girl
„Hormones are like fertilizer: it´s good for clover, but it kills orchids“1
Boy?, else girl
In the first weeks after fertilization, both sexes experience the same development. The fertilized egg has everything it needs to produce a boy or girl. The decisive factor is a gene on the Y chromosome, which triggers the development of the testicles (gonads) in the male embryo approximately in the seventh week. The testicle, in turn, produces androgens as if masculinity depended on them; oh well, it does. At the same time, it also produces small amounts of female sex hormones.
Female embryos, on the other hand, start producing ovaries about eight weeks later, which in turn generate estrogen and progesterone, but also small amounts of testosterone. It is interesting that the further differentiation of the inner genitals is exclusively controlled by the different concentrations of androgen.
If one castrated the testicles at the beginning, a development would continue in female direction. Androgens control the further development of the embryo and could even reverse the sex. That is why we have to distinguish between genetic and gonadal sex.
Estrogen, on the other hand, does not seem to have any influence on the further development of the female individual. Put simply, an embryo would always develop into the female direction unless androgens were added, which is nothing that did not actually happen before (more later under » testosterones).
The pituitary gland produces luteinizing hormone (LH), follicle stimulating hormone (FSH) and prolactin. Their effect depends on whether they meet testicles or ovaries:
The male loop
- presence of counter-sexual individual
- other sexual stimuli
- success / failure
The female loops
Yep, plural, since two dominant gonads interact with each other in the female circulation. Estrogen is associated with mating and progestin with pregnancy. Periodicity is both induced by the hypothalamus and controlled by the networked regulatory circuits.
During the pituitary gland, there is initially mainly a release of FSH. As a result, a follicle matures in the ovaries. As soon as a certain ratio of LH and FSH is exceeded, ovulation happens. The egg leaves the follicle, which transforms into the so-called corpus luteum producing progestorone.
In case of no fertilization, the progestorone inhibites LH production and the corpus luteum shrinks. As a result, the progestorone level lowers. The uterine mucosa cannot be preserved and is rejected during menstruation2.
These control mechanisms are already present and functional from birth. However, the values during childhood are almost zero. Only in boys does the reduction of testosterone take place after six months. Before that, their values are about 30 percent of an adult male. So far, it unknown why this is the case.
Shortly before puberty, hormone production begins and the external sexual characteristics continue to further differentiation. The release of estrogen causes the development of a wider hip and a stronger formation of fatty tissue. Testosterone, on the other hand, promotes bone growth and increases muscle mass. Under the influence of the gonadal hormones (estrogen and testosterone) sexual interests increase, especially in boys, as well as cognitive performance, aggressive and assertive behavior2. There is good reason to believe that the activation of hormones at this stage is also responsible for psychological differences.
Boys are two years behind girls in their development. One assumption is that they could take more time to develop their bodies due to their lower parenteral investment.
Alarming results show that girls who grow up without a father tend to be sexually active and mature earlier. They are also more likely to enter into an unstable relationship3.
Testosterone is the most important of the male sex hormones, the androgens. As mentioned before, the addition of androgens at different times during the foetal development leads to „masculinization“ of the external and internal genitalia and even behavior. This was not only shown in rats, but there are also results from humans.
Before the side effects were known, artificial progestins were administered to mothers who were threatened with termination of pregnancy. As a result, affected boys completed sex development earlier. In addition, they showed a higher willingness for physical aggression than siblings4. In affected girls, ovaries and uterus were formed, while the outer genitals were masculine. If left untreated, the outer genitals further developed into the masculine direction. In addition, these patients showed little interest in infants, but more in their professional careers. They preferred to play with boys and „boy toys“. Furthermore, they dressed more practically and less attractively and had a preference for physical competitive situations. All in all, they were dissatisfied with the female role5.
Testosterone and anxiety & social interest
So there seems to be a connection between testosterone and social interest and physical competition. Another study established a first relationship between testosterone and anxiety in boys. Six- to 18-month-old boys reacted less anxiously to frightening toys the higher the concentration of testosterone in their umbilical cord was.
In addition, the higher the amount of testosterone in the amniotic fluid, the less social interest and the less eye contact there is6. In girls there is also a positive correlation between maternal testosterone and their preference for „boys‘ toys”7.
These studies are interesting and therefore mentioned here. It would be premature to draw general conclusions from this. The studies are very specific and at the time they did not take into account current standards and findings. For example, at the time researchers considered a one-dimensional scale, on which the slider was moved back and forth between male and female. But actually, we are dealing with four different effects of (de)feminisation and (de)masculinisation8.
Testosterone and sports competition
A study with rugby players shows that testosterone in women always increases before and during a game. Winning or loosing the game makes no difference on females testosterone levels. Estradiol correlates with androgen levels10.
Men only increase their testosterone level when they expect to play or fight with a serious opponent9. Loss leads to a decrease in testosterone, but only if the loser attributes the loss to his lack of competence. If, on the other hand, he think that external circumstances are to blame for his failure, he has a mitigating decrease in testosterone (» more about causal attribution of success and failure).
According to various studies, the more power-motivated a person is, the higher the increase in testosterone levels when winning11. Testosterone boosts willingness to engage in risky behavior, coordination, cognitive performance, muscle growth, confidence and concentration. Which is why androgens are used as doping in sport.
Testosterone and leadership potential
Testosterone has a positive effect for both sexes on assertiveness, dominant and self-confident appearance and career orientation12.
Schaal et al., 1995 measured the testosterone concentration in boys at the age of 13 years and found the following. Boys who were judged to be assertive and also social leaders had the highest testosterone levels. These boys were not the most physically aggressive.
Strong boys who were not leaders did not have particularly high testosterone levels. The most aggressive boys showed the lowest testosterone levels. From this we can deduce that aggressiveness has a negative effect on hormone production. Success, on the other hand, seems to be a prerequisite for rank and testosterone in boys.
In women, testosterone, androstendione and estradiol correlate positively with their own self-assessment of reputation, leadership and popularity. However, this did not correspond to the image of the others. They tended to assign a higher status to women with a lower hormone concentration. Girls who showed the rather male, direct strategy in rank behaviour did not meet long-term success. Competent alliance building is the better strategy in female groups.
High levels of androgen and estradiol are also associated with a higher number of sexual relationships13.
» next topic:
Who would have thought that the subject of hormones would lead us to the different dominance strategies of the sexes?
- Bischof-Köhler 2006, p. 344
- Bischof-Köhler 2006, p. 184
- Comings et al., 2002 according to Bischof-Köhler 2006, p. 210
- Reinisch, 1981
- Bischof-Köhler 2006, p. 190
- Jacklin et al. 1983 according to Bischof-Köhler 2006, p. 193
- Hines et al., 2002
- Bischof-Köhler 2006, p. 184
- Mazur & Booth 1998
- Bateup et al., 2002
- Bischof-Köhler 2006, p. 302
- Archer, 2005 nach Bischof-Köhler 2006
- Cashdan 1995 nach Bischof-Köhler 2006