Of the 100 longest-lived people in the past 30 years, only four were men. On both sides of the globe, men live on average less than women. France is no exception. According to a recent INSEE study, life expectancy at birth for women is 85.8 years compared to 80.3 years for men for the period 2020-2025. Almost six years of difference!
Since the beginning of the 20th century, the two sexes have tended towards identical lifestyles, the causes of mortality are generally similar, and yet their lifespan remains unequal, notes Athanase Benetos, professor of geriatrics and biology of aging at the CHRU of Nancy. For this Inserm researcher, three scientific hypotheses stand out. “There are no certainties, but advances in recent decades have shown the benefits of estrogen.” This female sex hormone would somehow protect women from cardiovascular disease and osteoporosis. “It has an antioxidant effect which plays a role in aging and lower mortality, particularly for cardiovascular disorders.”
Besides hormones, men would be disadvantaged because of… the length of their chromosomes! “Like the little plastics found at the end of shoelaces”, chromosomes are made up of four endings – telomeres – whose length plays a role in life expectancy. Professor Benetos has studied them for a long time. Over the course of a lifetime, every human, regardless of gender, sees their telomeres shrink. “Males have had shorter telomeres since birth, and although telomere wear is equivalent in both sexes, they reach critical size earlier than their female counterparts.” A difference that is still not very well explained today. “A lot of scientists think it’s due to estrogen, but that can’t explain why this difference exists from birth to the end of life. It’s genetic,” says the specialist.
Still at the level of the chromosomes, the possession of the Y chromosome plays against them. Recall that female organisms have chromosomes of identical types (XX) while males have chromosomes of distinct types (XY). The X “contains a lot of genetic information outside of sex determination. As women have the same chromosome twice, this allows them to choose the best genes from each X”.
For the professor, it is possible that all of these three factors play a role. Women would be biologically more advantaged, but this is not without counterparts. “They certainly have the advantage of having a better life expectancy, but their state of health at the end of life is more impaired than that of men at the same age. In addition, they are sometimes less helped when they find themselves alone and have more difficulties. Their longevity has a price.
