Why Do You Get Goosebumps When It's Cold?

Look closely at your arm. Those tiny bumps are actually hair follicles being pulled up by super small muscles attached to each hair. Think of them like a thousand tiny hands tugging on strings.

When you feel cold, your body tries to trap heat inside its fuzzy blanket. These tiny muscles contract and pull the hairs upright, making that blanket thicker. It also helps if something brushes against you because the raised hairs act like shields.

Long ago our ancestors had lots of fur. When they got scared or cold, their fur puffed out to look bigger and stay warm. Even though we do not have much hair left, those tiny muscles still remember how to work!