Men's testosterone levels largely determined by where they grow up

Testosterone levels in men are largely determined by their environment during childhood, according to a new study.

The study conducted by the University of Durham suggests that men who grow up in more difficult conditions where there are many infectious diseases, for example, will likely have lower testosterone levels later than those who spend their childhood in healthier environments.

The study, published in Ecology of nature and evolution, challenges the theory that testosterone levels are controlled by genetics or race.

As high levels of testosterone can potentially increase the risk of prostate hypertrophy and cancer, the researchers suggest that any screening for risk profiles might have to take into account the child's environment. A man.

The study found that Bangladeshi men who grew up and lived as adults in the UK had significantly higher levels of testosterone compared to relatively affluent men who grew up and lived in Bangladesh as a "male". adults. Bangladeshis in Britain also attained puberty at a younger age and were taller than men who lived in Bangladesh as children.

Researchers say the differences are related to energy investment because it may be possible to have high levels of testosterone if there are not many other demands on the body such as the fight against infections. In environments where people are more exposed to diseases. nutrition, developing males direct energy to survival at the cost of testosterone.

The researchers collected data from 359 men on height, weight, age of puberty and other health information as well as saliva samples to examine their testosterone levels. They compared the following groups: men born and still residing in Bangladesh; Bangladeshi men who moved to the UK (London) as children; Bangladeshi men who moved to the UK at adulthood; second-generation men, born in the United Kingdom, whose parents were Bangladeshi migrants; and Europeans of British origin.

The lead author of the study, Dr. Kesson Magid of the Department of Anthropology of the University of Durham (UK), said: "The absolute testosterone levels of a man is not related to his ethnic background, children. "

Men with higher levels of testosterone are at higher risk for the potentially harmful effects of this hormone on health and aging. Very high levels may mean an increase in muscle mass, an increased risk of prostate diseases and have been linked to higher aggression. Very low levels of testosterone in men can include lack of energy, loss of libido and erectile dysfunction. The testosterone levels of the men in the study however were all in a range that would not likely have an impact on their fertility.

Co-author Gillian Bentley of the University of Durham commented: "Very high and very low testosterone levels may have implications for male health and it would be important to know more about the circumstances of the childhood of men to get a better idea of ​​their conditions, or diseases. "

Aspects of male reproductive function remain variable until the age of 19 and are more flexible in the beginning rather than at the end of childhood, according to research. However, the study suggests that in adulthood, men's testosterone levels are no longer strongly influenced by their environment.

Senior co-author Gillian Bentley and her colleagues also discovered that the environment in which girls grow up can affect their hormone levels, their fertility and the risk levels for reproductive cancers at the same time. 39, adulthood.

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More information:
Kesson Magid et al, the ecology of childhood influences salivary testosterone, pubertal age and stature of Bangladeshi Bangladeshi migrant men, Nature Ecology and Evolution (2018). DOI: 10.1038 / s41559-018-0567-6