Here a male surrounded by his harem is emitting a cry to mark his territory. Elephant seals are one of the species in which females outlive males. Credit: © Isabelle CHARRIER / Neuro-PSI / CNRS Photothèque

An international team of researchers has found evidence that shows female mammals besides humans also live longer than males. In their paper published in Proceedings of the National Academy of Sciences, the group describes how they compiled and analyzed demographic data from a large number of animal populations and what they found.

Scientists have known for many years that in humans, females tend to live longer than males. The reason is still up for debate. Some suggest it is because women have two copies of the same chromosome; others believe it is because men live riskier lives; others yet argue that it is due to age-associated diseases. Whatever the reason, prior research has shown that with humans, there is a 7.8 percent gap in longevity. In this new effort, the researchers have found evidence indicating that the same is true for most other mammals.

To better understand longevity rates for mammals in general, the researchers collected and analyzed demographic data for 101 species covering 134 populations. They also separately studied longevity in gorilla and orca populations to learn more about why there are gender differences in mammals at all.

In looking at their results, the researchers found that females outlived males in 60 percent of the species they studied. They also found that female mammals live on average 18.6 percent longer than males—a gap more than twice that of humans. The researchers also found that as a population ages, the wider the gap in longevity grows—a finding also true for humans. Prior research has shown that nine out of 10 supercentenarians are women, for example.

Graphic overview of average lifespan of female and male mammals in wild populations. Credit: Proceedings of the National Academy of Sciences (2020). DOI: 10.1073/pnas.1911999117

The researchers note that many studies into longevity in mammals have been conducted. But most were focused on a single species or a group of related species. They claim theirs is the widest-reaching study of its kind to date because of the large numbers of species that were included. They also note that they found that the longer a species of mammal is studied, the more accurate estimations of their longevity become. And groups that have been studied the longest show some of the biggest gaps in longevity—some as much as 20 percent.

More information: Jean-François Lemaître et al. Sex differences in adult lifespan and aging rates of mortality across wild mammals, Proceedings of the National Academy of Sciences (2020). Jean-François Lemaître et al. Sex differences in adult lifespan and aging rates of mortality across wild mammals,(2020). DOI: 10.1073/pnas.1911999117 Press release Journal information: Proceedings of the National Academy of Sciences

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