Castration may add up to two decades to a man's life, according to a new study that found that eunuchs living in Korea centuries ago lived significantly longer than other men.

Investigators looking at the court of the Chosun Dynasty found that eunuchs lived to 70 years of age on average, or about 14 to 19 years longer than men of similar socio-economic status, but still had their testicles, according to a study published in the journal Current Biology.

Researchers found that three of the 81 eunuchs studied lived to 100 or more, giving the group of eunuchs a centenarian rate that is 130 times higher than it is in developed nations today. During the Korean Chosun dynasty, which lasted from 1392 to 1910, boys in Korea were sometimes castrated to gain early access to the palace. 

Throughout history, eunuchs were mostly employed as guards or servants in harems in the Middle East and Asia, eunuchs in Korea's Chosun court were allowed to marry and had families through adoption.

Researcher Kyung-Jin Min of Inha University and Cheol-Koo Lee of Korea University believes that the long life of the eunuchs was not simply attributable to their privileged lifestyle in the palace and adds an "important clue for understanding why there is a difference in the expected life span between men and women," she said in a statement.

"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. Surprisingly, the average lifespan of the kings and male members of the royal family who spent their entire lives inside the palace had the shortest lives of all, typically living only into their mid-forties.

Past studies have shown that female mammals generally live longer than males, and one explanation is that testosterone weakens the immune system and can increase the risk of coronary heart disease.

Researchers found that castration typically lengthens the lifespan in animals but studies on people have been inconclusive. Past research found that while the lifespan of castrated mentally ill, institutionalized men were significantly longer, the lifespan of castrato singers was not significantly different from their non-castrated counterparts.

However, while the latest discovery may offer some clues to longevity and better health, in the meantime, researchers joked that men should "stay away from stresses and learn what you can from women," according to a news release.