How did the camel get its hump?

from BBC Wildlife Magazine,     Submitted by Jo Price

Find out why a camel’s hump is so useful in the desert.

Camels in Sahara Desert

Scientists have found fragments of a camel’s leg bone from over 3.5 million years ago in the Canadian Arctic.

These early camels were nearly twice the size they are now – over 3m tall – and evolved their fat-filled hump to help them survive the cold. The Arctic was warmer back then and forested with conifer and birch.

As the Ice Age came, the camels moved south. On reaching the deserts they found themselves surprisingly suited to their new environment.

Their big flat feet, evolved for spreading their weight over snow, helped them to walk on sand. The thick fur on their backs, originally developed to keep them warm, now shielded them from the sun. And their three eyelids, once so effective against snowstorms, now protected their eyes from wind-blown sand.

The camel’s hump is also useful in the desert. Almost all of its fat is stored there, rather than being evenly distributed over its body, so it stays cool in warm environments.

The hump isn’t rigid: if a camel uses up its supply of fat, the hump shrinks and flops over to one side, only reverting to its upright shape when the animal has fed and slept.

Extracted from QI: The Third Book of General Ignorance (Faber & Faber, £14.99