In all human populations, average lifespans are longer for women than for men. Moreover, nine out of ten supercentenarians--that is, people 110 years old and up--are women. But what about for other mammals, in the wild? A team led by Jean-François Lemaître, a CNRS researcher at the Biometry and Evolutionary Biology laboratory (CNRS / Claude Bernard Lyon 1 University / VetAgro Sup), compiled demographic data for 134 populations of 101 mammalian species--from bats to lions, orcas to gorillas--making their study the widest reaching and most precise to date. In 60% of the cases, female mammals live longer than males: 18.6% longer on average (versus only 7.8% longer in humans). Is this because male mortality rates rise faster with age? Not necessarily, according to Lemaître's team: for about half of the populations studied, the rise in mortality with age is even more pronounced among female mammals. However, mortality risk is lower among females at all ages.