What mammal has the social life of an insect, the cold-bloodedness of a reptile, and the metabolism of a plant? Bald and buck-toothed, naked mole-rats may not be pretty, but they are extraordinary. Thomas Park explains how mole rats' peculiar traits have evolved over millions of years to make them uniquely suited to survive harsh conditions - especially long periods without oxygen. Lesson by Thomas Park, animation by Chintis Lundgren.