By: Rachael Liu

For half a century, people have known that as men age, they lose their Y chromosomes. However, nobody knew the significance of this process until now.

Researchers at the Department of Molecular and Experimental Medicine conducted a study where they induced Y chromosome loss in mice to see what would happen. They found out that when the mice lost their Y chromosomes, scar tissue built up in the heart, causing heart failure and shortened life span. Researchers think that the same thing will happen to humans and that the loss of Y chromosomes is the reason why women live longer than men on average.

Lars Forsberg, a researcher at Uppsala University said that “At least 40 percent of males lose the Y chromosome from some of their blood cells by age 70. And by age 93, at least 57 percent have lost some of it.”

So far, the only way to reduce the risk of losing Y chromosomes is to stop smoking; of course some people don’t smoke in the first place. The loss of Y chromosomes has no relation whatsoever to low testosterone levels, so taking testosterone supplements will not have any effect.

The researchers did find that they could protect the hearts of the mice by blocking TGF-beta, a key molecule in causing scar tissue to build up around the heart. The thing is, this wouldn’t work on men who have already lost their Y chromosomes.