(CBS News) Men who are castrated may trade what they're losing for extra years of lifespan, new research suggests.
A genealogical study of eunuchs of the Korean Chosun dynasty published in the Sept 24 issue of Current Biology finds that men who were castrated lived almost 20 years longer than other men of the same time periods.
"Our study supports the idea that male sex hormones decrease the lifespan of men," wrote the researchers, led by Kyung-Jin Min of Inha University.
Animal studies show castration - removing the source of male sex hormones, the testes - can prolong lifespan in males, but the effect hasn't been seen in humans.
To find out, the researchers took a close look at the the Chosun Dynasty in Korea that occurred from 1398 through 2010. During the dynasty, many boys were castrated purposefully to gain the benefits from access to the royal palace where they would be allowed to serve as guards. The eunuchs were also allowed to marry - which was banned in the Chinese Empire at the time - and continue their lineage by adopting castrated boys or normal girls.
The researchers say although these new families weren't blood -related, the bonding in the family was believed to be just as strong.
What helped the researchers for their study was people throughout the dynasty kept detailed records of their genealogy to prove they belonged in the noble class. Dr. Min and his colleague Cheol-Koo Lee of Korea University looked at records of 385 eunuchs and found the full lifespans identified for 81 of them. The researchers found the eunuchs outlived other men of the same era 14 to 19 years longer on average.
What explains the findings? Dr. Min told Reuters it wasn't because eunuchs were granted the privileged lifestyle once in the palace. In fact, life expectancy for males in the royal family was only around 47 years old.
"Except for a few eunuchs, most lived outside the palace and spent time inside the palace only when they were on duty," Min told Reuters.
Three of the 81 eunuchs lived to over 100, rates 130 times that as seen in modern developed countries. For example, one out of 4,400 Americans lives to reach the century mark.
While the research sounds like it should belong in a Mel Brooks movie, the scientists say their findings may actually explain well-established differences in lifespan between genders. The researchers cite past research that suggests male sex hormones like testosterone could negatively affect immune system function, and the hormones predispose men to a greater risk for heart attacks and cardiovascular events.
"This discovery adds an important clue for understanding why there is a difference in the expected life span between men and women," Min said in a press release. "For better health and longevity, stay away from stresses and learn what you can from women."