Testosterone may cut short lives of men, study of Korean eunuchs finds

A study of historical data showing Korean eunuchs far outlived their non-castrated contemporaries provides new evidence about why women generally live longer than men, scientists said.

The study, published on Monday in the scientific journal Current Biology, used detailed genealogical records of the imperial nobility during Korea's Joseon dynasty, from the late 1300s to the early 1900s.

According to the data, most men, including kings and royal family members, died in their late 40s or early 50s. But noble-class men who were castrated lived, on average, to the age of 70.

Study author Dr Min Kyung-jin of South Korea's Inha University said the reason is probably the male hormone testosterone.

"Testosterone is known to increase the incidence of coronary heart disease and reduce immune function in males," he said.

Castration "removes the source of male sex hormones", the study notes, adding the practice has already been proven to help male animals live longer.