Castrated men living in Korea centuries ago outlived other men by a significant margin. The findings, reported in the September 25 issue of Current Biology, suggest that male sex hormones are responsible for shortening the lives of men, the researchers say.
The evidence comes after careful study of genealogy records of noble members of the Imperial court of the Korean Chosun dynasty (AD 1392-1910).
"This discovery adds an important clue for understanding why there is a difference in the expected life span between men and women," said Kyung-Jin Min of Inha University.
The castrated boys in Korea lost their reproductive organs in accidents—usually after being bitten by dogs—or underwent castration purposefully to gain early access to the palace. Eunuchs were allowed to marry and had families by adopting castrated boys or normal girls.
People in those days kept careful genealogy records as proof that they were of the noble class. By poring over those records, Min and colleague Cheol-Koo Lee of Korea University found that eunuchs lived 14 to 19 years longer than other men did. Amongst the 81 eunuchs they studied, three lived to the ripe old age of 100 or more, a feat of longevity that remains relatively rare even in developed countries today.
The incidence of centenarians among Korean eunuchs is at least 130 times greater than it is in the developed countries, Lee notes, and that can't be explained simply by the benefits of life in the palace, either. Most eunuchs spent as much time outside the palace as they did inside it. And, in fact, kings and male members of the royal family had the shortest lives of all, typically surviving only to their mid-forties.
The findings may offer some clues to life extension and, in the meantime, men might take heed, Min and Lee quip. "For better health and longevity, stay away from stresses and learn what you can from women."
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Min et al.: "The lifespan of Korean eunuchs" Current Biology, 2012.