For men, no hormone is more important than testosterone. A man's testosterone level influences a broad range of his characteristics, both physical and psychological — from his sex drive, to beard growth to the health of his heart, as HealthLine has reported. But what causes a man to have a healthy level of the vital male hormone, or an unhealthy one?
While genetics or even race have generally been considered the main factors in determining testosterone levels, a new study by scientists at England's Durham University suggests that the most important factor determining the testosterone level in an adult man may be simply where he lived as a boy, according to the research paper published Monday in the journal Nature Ecology & Evolution.
The study found that men who spent their childhoods in unhealthy environments with a prevalence of infectious diseases and poor nutritional supplies exhibited lower levels of testosterone as adults than men who spent their boyhoods in regions with more advanced sanitation, diet, and medical care, according to a summary of the Durham University study published by Live Science.
The study looked at men who had a common ethnic background — in the case of the study, Bangladeshi men — but grew up in varying environments. The 359 men in the study were divided into groups based on where and how they grew up, according to Science Daily.
The groups were well-off men who lived in Bangladesh both as children and as adults; men who moved to London in the United Kingdom as children; men who moved there from Bangladesh as adults; second-generation Bangladeshis who grew up in the U.K.; and ethnic Europeans born in the U.K..
The men who grew up in the United Kingdom had notably higher testosterone levels as adults than the men who grew up in Bangladesh, an economically developing country, even compared to the men from financially well-off backgrounds who spent their childhoods in Bangladesh, according to the study.
"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 Durham University anthropologist Kesson Magid, the lead author of the study titled "Childhood ecology influences salivary testosterone, pubertal age and stature of Bangladeshi UK migrant men."
According to a report on the study by the British Independent newspaper, growing up in physically and mentally challenging environments may cause the body to consume energy that would otherwise be used to produce the vital testosterone hormone.
"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," study co-author Gillian Bentley said, as quoted by Medical Daily.
Low testosterone levels have been linked to fatigue, lowered sex drive, and erectile difficulties, as well as mood disorders and inadequate muscle mass. High testosterone levels, on the other hand, are associated with prostate disease as well as behavioral disorders such as high levels of anger and aggression, according to Medical Daily.