by Stanley Azuakola
In Nigeria, life expectancy for males is 49 years, while it is 53 years for females. This kind of statistics generally rings true in most countries in the world — women live longer than men. But why?
Various theories have been put forward to explain it, and on Monday yet another theory was born, as scientists led by Kyung-Jin Min of South Korea’s Inha University announced that they have new evidence about why women live longer than men. Their working sample was a study of historical data which showed that castrated Koreans lived longer than their non-eunuch contemporaries.
The study was published in the scientific journal “Current Biology.” Detailed genealogical records of the Imperial nobility during Korea’s Joseon dynasty, which spanned more than 500 years from the late 1300s to the early 1900s was used.
This what they discovered from the data: non-castrated men (including kings and royal family members) died in their late-40s or early-50s; while noble-class eunuchs lived averagely up to 70 years.
The reason according to the study author is the manly hormone, testosterone:
“Testosterone is known to increase the incidence of coronary heart disease and reduce immune function in males,” he said.
Castration which has been proven to help many male animals live longer involves the removal of the source of male sex hormones. Castration also cuts off the possibility of reproduction, which Kyung-Jin noted could also be a factor.
“According to one of the leading theories of aging, aging occurs at the expense of reproduction,” he said, because “the body has limited energy that can be used either to keep up reproductive function, or else to keep up everything else.”
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Although the eunuchs could not father children biologically, they married, adopted and raised children, and generally lived lives very similar to their non-castrated peers.
“In order to eliminate socioeconomic factors that could have affected lifespan, the lifespan of the eunuchs was compared to the lifespan of men from other Yan-ban (noble class) families with a similar socioeconomic status,” Kyung-Jin said.
And “to exclude genetic factors that could have affected the lifespan, we compared the lifespan of eunuchs with multiple Yan-ban families.”
Modern men looking to extend their lifespan could consider “testosterone reduction therapy,” but Kyung-Jin said it’s probably premature.
For one thing, it is not clear if it would have an effect if the therapy were started at an older age — the eunuchs were all castrated as children.
And for another, the therapy could have side effects that some men may feel make that longer life less worth living.
“We may need to consider the side effects of it,” Kyung-Jin said, “mainly, reduction of sex drive in males.”