Why Do Women Live Longer?

We know that women live longer than men, but why?

In 2017, the average life expectancy of women in the U.S. was 81.1 years but only 76.1 years for men. Longevity differs by country but the sex disparity is true for all humans and for other species as well.

A study at the University of New South Wales, Sydney published in March 2020 examined the life spans of 229 species and discovered it is related to sex chromosomes.

Across the animal kingdom, individuals with identical sex chromosomes — including women with double Xs — live nearly 18% longer than their counterparts with mismatched chromosomes.

The Secret to a Long Life? Matching Sex Chromosomes, Science Daily

Among mammals, insects, fish and some reptiles, females have matching sex chromosomes [XX] whereas males do not [XY]. In all of these classes females live an average of 20.9% longer and sometimes a lot longer. The study found that female German cockroaches (Blattella germanica) live 77% longer than males. Ewww!

Among birds and butterflies the arrangement is opposite. Male birds have matching sex chromosomes [ZZ] whereas female birds do not [ZW]. In this case the males live longer, but only about 7.1%.

Mallard pair, female and male (photo from Wikimedia Commons)

More study is needed to discover why male birds don’t reach the longer life spans that female mammals and insects are able to achieve.

Learn more at “The secret to a long life? Matching sex chromosomes” in Science Magazine.

p.s. Life expectancy in the U.S. has been dropping since 2014.

(photos from Wikimedia Commons; click on the captions to see the originals)

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