Research on Mammals Explains Why Women Live Longer: Genetic Differences are Key
A new study on the lifespan of wild animals shows that females live longer than males.
The study found that, on average, females are 18.6% longer-lived than the same species’ males.
This is much greater than the difference between men and women who have been carefully studied (about 8%).
Scientists say that the differences between species are due to the combination of specific gender features and local environmental factors.
In every population, women live longer than men, so that in the 110-year-olds, nine out of ten are women.
The pattern has been consistent since accurate birth records began in the 18th century.
Despite the same assumptions being made for animal species, there is a lack of large-scale data on wild animals.
Male mountain goats are more susceptible to local environmental factors, while females are not.
Now, an international team of researchers has studied estimated age-specific mortality rates for 101 different species.
In 60% of the populations analyzed, women’s lifespans are longer than men’s. On average, they live 18.6% longer than men.
Female elephant seals, one of the longest-lived species.
Dr. Jean-François Lemaître, lead author from the University of Lyon, France, says: ‘Lifespan and the rate of aging across species may be the interaction between environmental conditions and gender genetic variation.’
Taking mountain goats as an example, researchers can gain good data from different populations.
In places where natural resources are consistently available, lifespan shows little difference. But in a particularly harsh winter, males’ lifespan is shorter.
Dr. Lemaître says: ‘Male mountain goats use a lot of resources for sexual competition, increasing their weight, and they are more sensitive to environmental conditions.’
‘The size of the lifespan differences is due to the interaction of these specific genetics, this fact is that compared with women, men devote more resources to specific functions as well as local environmental conditions.’
The research group found that even though women’s lifespans are longer than men’s, this does not mean that men’s mortality risk increases as they age. The expected male mortality rate is always higher, but as they age, the mortality rates of men and women are approximately the same.
A recent study in the field shows that genetic differences between men and women are key.
In humans, our cells contain different chromosomes depending on gender. Females have two X chromosomes, while males have one X and one Y. The theory is that the extra X in females protects against harmful mutations, and this is also the case in other species.
The authors of this new study on wild animals say that the two studies are complementary.
Dr. Lemaître says: ‘They show that in XX or XY systems, XX or females’ lifespan is longer, therefore, there is clearly a role for sex chromosomes.’
‘We show in our paper that differences between species are very large, this means that other factors need to be considered to explain these differences.’
