How the rhino got his woolly

[Still Waters]

NOWADAYS, elephants and rhinoceroses are tropical species. Until recently, though, they wandered as far north as the Arctic Ocean. The last woolly rhino died about 8,000 years ago. Woolly mammoths lasted another 3,500 years, succumbing only when human beings arrived in their Siberian refuges. What no one has known, however, is when and where these animals evolved the eponymous coats that allowed them to range in such high latitudes. The best guess was that they grew them gradually, as ice began to grip the world 2.6m years ago.

http://www.economist...een-tibetan-how