It is well-known that women live 7.8% longer than men, but what about orcas and gorillas and bats and lions? Scientists had long observed the lives of female mammals, but no one had quantified their lifespans across species worldwide.
A new study in the Proceedings of the National Academy of Sciences does just that, compiling data on 101 species of mammals. Drumroll: Female mammals live 18.6% longer than male mammals throughout the animal kingdom. This is news!
The researchers found that in 60% of the 134 animal populations they looked at, females outlived males. They attribute the differences to genetic and environmental factors, as well as differing reproductive costs. For example, in some species, males and females may live equal lifespans in favorable environments, but when famine strikes, the sex that expends less energy on size and sexual dominance may live longer. Researchers emphasize that there are many variables involved.
No overt difference in aging rates between male and female animals was observed.
Lifespan differences can be notably large: Female lions in the wild live, on average, 50% longer than male lions.