Differences in life expectancy between women and men can be explained by their chromosomes according to researchers.
I’life expectancy of a human at birth is 79.8 years for males and 85.7 years for females. women in 2019 in metropolitan France, according to INSEE. In animal species, life expectancy differs: in mammals, females tend to live longer than males, while in birds, they tend to die first.
A difference in chromosomes
A study published in Biology Letters demonstrates that these differences are due to chromosomes of each sex. According to researchers, gender heterogametic, i.e. having two sex chromosomes different as is the case in humans (X and Y), runs a higher risk of mutations. Ihe homogametic sex, on the other hand, that is to say the one having two identical sex chromosomes as is the case in women (X and X), will be able to compensate for these mutations thanks to a version of the uncomfortable non-mutated present on the second chromosome.
To arrive at this result, the researchers compiled data on the longevity of males and females of 229 different species. “We have not only looked at life expectancy data for primatesothers mammals and birds, but also reptilesfrom Piscesfrom amphibiansfrom arachnidscockroaches, grasshoppers, bumblebees, butterflies, and moths, among others”details Zoe Xirocostas from the School of Biological, Earth and Environmental Sciences in Sydney (Australia) and lead author of the study.
The researchers found that the homogametic sex lives an average of 17.6% longer than the heterogametic sex. Nevertheless, when females are homogametic, their life expectancy is 20.9% higher than that of males. Conversely, when males are homogametic, their life expectancy is only 7.1% higher than that of females. “Our results demonstrate the importance of considering chromosome morphology, in addition to sexual selection and environment, as potential drivers of sexual dimorphism and advance our fundamental understanding of the mechanisms that shape the lifespan of a organization”conclude the researchers.
Life expectancy in good health in France
A study by the Department of Research, Studies, Evaluation and Statistics (Drees) of the Ministry of Health, published in October 2019, concluded that from the age of 65, a woman has an average of 23.2 years left to live, but only 11.2 years without disability, that is to say without “being limited in her daily activities”. For a 65-year-old man, the additional life expectancy is 19.4 years, but only 10.1 in good health.
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