Research on testosterone and behavior up to the year 2000 was summarized by the Dabbs couple in the entertaining classic “Heroes, Rogues, and Lovers: Testosterone and Behavior” which is freely available on the Internet [25]. Since then, experimental research has exploded. Behavioral studies following small doses of testosterone are particularly fruitful. Carole Hooven provides the current status in “T for testosterone” [26]. Robert Sapolsky provides a panoramic overview of hormones, the nervous system, and behaviour in “Violence and Compassion” [27].
We, on the other hand, will limit ourselves to a more pedestrian level, namely what we have to say to Ueli Maurer (and Donald Trump).
Testosterone has been known since 1935. This tiny molecule consists of 49 atoms - 19 carbon, 28 hydrogen, 2 oxygen - and determines whether we become a man or a woman. There are several variants with slightly different spectra of action [28], but for our purposes we will group them together as “testosterone”.
In the first trimester of pregnancy, the male embryo does not yet have testicles but is already producing testosterone, which stimulates the development of the testicles, which in turn later produce larger amounts of testosterone and thus trigger the development of the male sex organs and male physique [26]. Also, under the influence of testosterone, the testicles descend into the scrotum, where they find the cooler temperature necessary for sperm production.
Without testosterone action and testicles, the embryo develops into a woman. This is proven by the natural experiment of those very rare men who are completely insensitive to this hormone due to a disorder of the testosterone receptor. These men develop physically and mentally into women; only the uterus and ovaries are missing, and their atrophied testicles remain in the abdomen [29]. There are also attenuated forms where development into a man remains incomplete.
Women also produce small amounts of testosterone, but the levels are almost ten times lower than in men and widely separated with no overlap.
The next chapter 8 will tell what testosterone does to the body. And this link takes you to the start of the book.
The German edition of this book can be ordered e.g. here.
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25. Dabbs, J., McBride and M. Dabbs, Godwin, Heroes, rogues, and lovers : testosterone and behavior. 2000, New York: McGraw-Hill; https://archive.org/details/heroesrogueslove00jame/mode/2up?view=theater.
26. Hooven, C., Testosterone: The story of the hormone that dominates and divides us, 2021, Octopus publishing.
27. Sapolsky, R., Behave - The biology of humans at our best and worst, Penguin Random House 2017.
28. Alemany, M., The Roles of Androgens in Humans: Biology, Metabolic Regulation and Health. Int J Mol Sci, 2022. 23.(19). https://doi.org/10.3390/ijms231911952.
29. Hughes, I.A., et al., Androgen insensitivity syndrome. Lancet, 2012. 380.(9851): p. 1419-28. https://doi.org/10.1016/S0140-6736(12)60071-3.