Hard guys have less testosterone in their blood

Hard guys have less testosterone in their blood

03/28/2012

American researchers have now discovered something astounding: Really tough men have less testosterone in their blood. Although the life of Tsimané in Bolivia is physically more exhausting than in the Western world, men there have a much lower testosterone level. The researchers have now come to the cause of the cause.

Testosterone dampens the immune system
The people of Tsimané in Bolivia live a simple hunter-gatherer life. They hunt in the rainforests and practice simple agriculture. Nevertheless, this people are puzzling the anthropologist. Benjamin Trumble of the University of Washington in Seattle and his colleagues found that male Tsimané males have on average one-third less testosterone in their blood than US males. This is reported by the online journal „Proceedings of the Royal Society B“.

The anthropologists were also surprised by this result. So far, men who perform hard physical work every day, a high testosterone levels assumed. Ultimately, however, the researchers developed another much more conclusive thesis. „A high level of testosterone cushions the immune system, so it makes sense to keep it low if you live in an area with many parasites and pathogens, such as the tsimané. "Trumble explains that the high testosterone content in the blood of American men is evolutionary luxury The testosterone levels of men in western industrialized countries are declining as they grow older, but this remains the same for tsimané.

Testosterone kick in competitive situations provides energy
One thing the Bolivian men have in common with those of Western industrialized countries. In competitive situations, the testosterone content in the blood increases in the short term. To confirm this, the researchers let the Tsimané play football against each other. The testosterone level was increased by 30 percent immediately after the competition. One hour later, he was still 15 percent above the average level.

In the sudden hormone kick in the competitive situation, the researchers saw a fundamental biological mechanism. In Western men they made the same observations. „Even in a highly pathogenic environment, it's important to boost your testosterone levels for short-term energy and competitive advantage, "said Michael Gurven of the University of California, anthropologist and co-author of the study.

Since 2002, the people in the context of „Tsimane Life and Health History Projects“ examined. As early as 2009, scientists around Gurven discovered that the Tsimané develop almost no cardiovascular disease.

Testosterone makes women more selfish
Earlier this year, British scientists found that the male sex hormone testosterone makes women more selfish and less cooperative. For the first time, a hormone was discovered that causes restrictions in interpersonal cooperation.

While scientists have long been aware that some hormones such as oxytocin promote cooperative behavior in economic tasks, they now wanted to look for a hormone with opposite effect. Therefore, Nicholas D. Wright and his colleagues examined the effect of testosterone on women. For the investigation, a pair of two women were each shown two consecutive images on the computer, one of which was to be determined, on which a sought-after motif hid. If both women chose the same picture, the next pictures followed. The subjects decided on different pictures, they should discuss with each other and agree by mutual agreement. The women went through the same experiment twice at intervals of one week. For one test, the women were given effect-free placebo and for the other they were given a dose of testosterone. In evaluating the test results, the researchers found that women could significantly improve their overall outcome through cooperative decisions without taking testosterone. The researchers around Nicholas D. Wright from the Institute of Neurology at University College London published their findings in the online journal „Proceedings of the Royal Society B“. (Ag)

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Picture: Karl-Heinz Laube