During the Chosun Dynasty, poor young men often chose to castrate themselves to live within the relative comfort of the palace walls.

Most of the eunuchs seen in Korean costume dramas are elderly, and the question is whether eunuchs typically lived longer than other men. Scientists have found that the average life span of a eunach during the period was 70 years, while men from noble families had an average lifespan of just 51 to 56 years.

Even more surprisingly three out of the 81 eunuchs studied actually lived past 100.

This is the first time Korean researchers have used historical data to prove that male hormone reduces men's life span.

"Scientists were aware that castration of mammals increased their life span, but we were not able to relate the findings to humans until now. This research proves that male hormones do cause an earlier death," a researcher said.

The scientists say they hope to use the data to figure out ways to increase the human lifespan. The research paper titled “The lifespan of Korean eunuchs” is available on the website of Current Biology (http://www.cell.com/current-biology/).