Researchers from the United States found that toxic masculinity might be the reason why women live longer than men. They studied male flies of the species Drosophila miranda and found that they have twice as many repeat DNA sections in their Y chromosomes that cause toxic effects, according to Mail Online.
They noted that as the flies are aging, repeat sections are freed to become active that causes toxic effects such as impaired memory and DNA damage, which in return causes shorter lifespans.
Although both male and female fruit flies have these repetitive sequences, males are more vulnerable because they are more abundant on Y chromosomes that men possess, representing a genomic liability.
Taking this study into account, this might explain why species of XY chromosomes like humans, females have longer lifespans while males die younger.
The researchers published the findings of their study, entitled "Toxic Y chromosome: Increased repeat expression and age-associated heterochromatin loss in male Drosophila with a young Y chromosome," in the journal PLOS Genetics.
Why Women Live Longer Than Men
Lifespan differences based on sex are prevalent across the tree of life and are influenced by the sex chromosomes, according to the study.
Particularly, female species of those with XY chromosomes live longer the male species. The study discusses that it could be due to the overall repeat sections in the Y chromosomes that shorten the lifespan of males in a phenomenon called the toxic Y effect.
SciTech Daily reported that Doris Bachtrog of the University of California, Berkeley studied male fruit flies which have twice the amount of repetitive DNA as females and a shorter lifespan. The study showed that when it is young, the insect's DNA is tightly packed, and repeat sections are not active.
But when the flies get older, repeat sections are activated as the DNA assumes a looser form. This then results in the toxic Y effect.
"We show that transposable elements located on the Y chromosome are less effectively silenced in male Drosophila," the researchers wrote. "The toxic Y effect appears more pronounced in a species that contains a larger Y chromosome with more repeats and more actively transcribed genes."
Link Between DNA Repeat Sequences to Aging
Daily Mail reported that Bachtrog and biologist Alison Nguyen's study support the theory on the general link between DNA repeat sequences and aging, which is poorly understood.
The duo added that the DNA repetitive sections in the Y chromosomes likely contributed to the physical effects of aging. But they emphasized that further investigation and research is necessary to uncover the specific mechanisms that underlie the toxic Y effects of repetitive DNA.
In conclusion, the researchers said that their findings demonstrated that repetitive sequences in Y chromosomes are a genomic liability that diminishes male fitness and shortens the lifespan of males.
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