No, that’s not the opening to a joke, bats really do live a long time.

Typically, a mammal’s longevity falls broadly in line with its mass. As mass increases, metabolism slows and lifespans get longer. We humans are a species that bucks the trend because we live considerably longer than mammals of similar or even greater mass than ourselves, but the formula holds in general.

There are 19 species of mammals that live longer than us relative to their body mass and 18 of those are bats.

So what gives? It turns out bats are very good at maintaining their chromosomes.