Hair
Hair protects your head and eyes from the sun. On other parts of your body, it helps you feel things brushing against your skin. And it helps to keep you warm. Most of a hair is made of dead cells.

Can hair really stand on end?
If you are cold or frightened, your hair may feel as if it is standing on end. A tiny muscle pulls on the root of each hair, levering it int a more upright position. As each hair moves, it pushed against the skin, making a 'goosebump'. Long ago humans had lots of body hair, and warm air would have been trapped in the little pits formed by goosebumps.

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