The Grapevine

Men's Testosterone Levels Influenced By Where They Grow Up, Study Suggests

Childhood surroundings could largely determine male testosterone levels, according to researchers at Durham University, England. The new findings challenge the theory that ethnicity and genetics are the determining factors.

The study titled "Childhood ecology influences salivary testosterone, pubertal age and stature of Bangladeshi UK migrant men" was published in Nature Ecology and Evolution on June 25.

"A man's absolute levels of testosterone are unlikely to relate to their ethnicity or where they live as adults but instead reflect their surroundings when they were children," said lead author Dr. Kesson Magid from the Department of Anthropology at Durham.

It was hypothesized that men who grow up in challenging conditions are more likely to have lower testosterone levels than those who grew up in healthier environments. As many as 359 male participants provided health data including their height, weight, the age of puberty, and other relevant details. Saliva samples were also taken to examine their testosterone levels.

The participants were divided into a number groups for comparison, including men who were born in and still live in Bangladesh, Bangladeshi men who moved to the U.K. as children, Bangladeshi men who moved to the U.K. as adults, etc.

The results revealed that migration before puberty was a strong predictor of testosterone levels. Bangladeshi men who grew up and lived as adults in the U.K. had notably higher levels of testosterone compared to the adult migrants or the men who grew up and lived in Bangladesh as adults.

The childhood migrants (particularly the ones who arrived in the U.K. before the age of 8) also reached puberty at a younger age and were taller than men who lived in Bangladesh throughout their childhood.

The research team believed that difference in energy investment is what leads to varying levels. That is, when environments expose them to more disease or poor nutrition, developing males use up energy for survival at the cost of testosterone.

"Very high and very low testosterone levels can have implications for men's health and it could be important to know more about men's childhood circumstances to build a fuller picture of their risk factors for certain conditions or diseases," added co-author Gillian Bentley, a professor at Durham.

Low testosterone can result in low sex drive, reduced muscle mass, mood problems, fatigue, and more. On the other hand, too much testosterone has been linked to an increased risk of prostate diseases and higher aggression.

While early childhood can have a significant impact, the new study showed that testosterone levels are no longer heavily influenced by their surroundings in adulthood. 

Bentley and her research team previously conducted a female version of the study which noted similar implications. The research, published in 2016, revealed that childhood environments could go on to influence the fertility levels of adult women.