Scientists may have figured out why women live longer than men

The mystery of why women live longer than men may have finally been solved, with scientists calling their findings a “crucial step” in understanding longevity.

Scientists may have figured out why women live longer than men — linking it to having two X chromosomes, which defend against ageing, a new study says.

The extra X provides a sturdy cellular structure that protects against gene mutation and sickness, according to a report published Wednesday in the journal Biology Letters.

“These findings are a crucial step in uncovering the underlying mechanisms affecting longevity, which could point to pathways for extending life,” the researchers write.

“We can only hope that more answers are found in our lifetime.”

Scientists may have figured out why women live longer than men. Picture: iStock

For the study, scientists from the University of New South Wales gathered data on the sex chromosomes and lifespan of 229 species, including insects, fish and mammals, according to The New York Post.

They found that animals with two of the same sex chromosomes — such as birds with two “Z” chromosomes — live nearly 18 per cent longer.

Their research piggybacks on a pre-existing theory known as the “unguarded X hypothesis,” which notes that one X can serve as a buffer against disease.

As the theory goes, only one X is activated in each of a woman’s cells, so a harmful mutation in one cell is less likely to effect all cells.

That makes mutation-related disorders “masked” more often in females, according to scientists.

It may have something to do with having two X chromosomes, which defend against ageing. Picture: iStock

By contrast, men are more likely to be exposed to the same types of mutations because their XY chromosomes only have a lone X.

But when the males of other species double up, they tend to live longer than females.

Overall, males live an average of seven per cent longer than females in species where males have two of the same sex chromosomes, according to the study.

When the chromosome pattern is the other way around — as in the case of humans — women live an average of nearly 21 per cent longer than guys.

But there may be other factors tied to longevity, such as fighting and risk-taking, the scientists said.

“Pressures to travel far to find a mate, establish a territory and compete with other members of your sex are not seen often in females,” said Zoe Xirocostas, who co-authored the report.

A study found that animals with two of the same sex chromosomes live nearly 18 per cent longer. Picture: iStock

Steven Austad, a University of Alabama at Birmingham expert on ageing, called the study promising.

“It plays some role in understanding sex differences in longevity,” Mr Austad, who was not involved in the research, told The Guardian.

A bigger role in childcare may also be tied to living longer, he said: “For instance, owl-monkey males live longer than females — and the males play a big role in infant care in that species”.

Originally published as Scientists may have figured out why women live longer than men