Why do we get goosebumps?

When you feel cold, or scared, or hear a song that moves you, tiny bumps rise on your skin and your hairs stand up. These are goosebumps, and they are a gift from your ancestors.

Each hair on your body has a tiny muscle at its root. When the brain senses cold or danger, it tells these muscles to tighten. The hair stands straight up and the skin around it bunches into a bump.

For a furry animal, this is useful. Standing fur traps a layer of warm air, like a jacket. In danger, it makes the animal look bigger — think of a cat facing a dog.

Humans have very little fur, so goosebumps no longer keep us warm or make us look fierce. The reflex simply never switched off. When music gives you goosebumps, your ancient alarm system is responding to emotion.