Why women outlive men: Evolution may hold answer

A new research study has offered a unique evolutionary insight into why women have a large lifespan as compared to men.

Globally, women have a life expectancy of 74 years comparable to men, who possess 68 years life expectancy.

For years, increased female longevity is often attributed to a healthy diet, genetic leverage, reduced disease risks, and healthy lifestyles.

But, evolution has yet to play its part in resolving the mystery that has shrouded female longevity for years.

As per new research published in Science Advances, not only do humans but also other mammalian species show similar lifespan gaps, with female mammals often living longer than males.

On the contrary, male birds often outlive female birds. According to study findings, women could continue outliving men irrespective of medical advancements and healthy lifestyles.

In the comprehensive study conducted by Johanna Stärk at the Max Planck Institute for Evolutionary Anthropology, the team analyzed around 1176 species, including rodents, moose, chimpanzees, and different types of birds.

As per their findings, 72 percent of mammal female species show higher longevity than males, by 12 percent on average. In birds, males have larger lifespans than females in 68 percent of the species.

In evolutionary perspective, differences in sex chromosomes could offer new answers. Mammalian females possess two X chromosomes and males have XY chromosomes, giving females an edge by shielding them from deadly genetic mutations.

Birds show reversal in chromosome pairing as males have two pairs of same chromosomes unlike females with two different chromosomes.

“Some species showed the opposite of the expected pattern,” Johanna Stärk said in a statement.

“For example, in many birds of prey, females are both larger and longer-lived than males. So sex chromosomes can only be part of the story,” added the study’s lead author.

According to researchers, the longevity differences between different sexes, including humans, are shaped by the blend of genetic differences, sexual selection, environmental factors, and parental genes.

In chimpanzees and gorillas, the female high survival rate is more common and rooted in “evolutionary processes”, suggested by the team.

“At least in terms of sex differences in survival, our species is not unique,” they added.