Most people at one time or another will get goose bumps. It’s a strange thing that happens to people's skin. The muscles at the bases of the hairs on your skin get very tense and they contract, much like your bicep muscle does when you flex your arm. These little muscles make tiny bumps all over our skin and these are called goose bumps. The name might seem weird, but it is used because goose bumps look like a goose’s skin when it doesn’t have any feathers.
We can’t control them. We get them when we are cold or when we get scared, but their purpose is still a bit of a mystery. Many scientists think goose bumps are a reflex left over from many thousands of years ago when our ancestors had a lot more hair on their bodies! Goose bumps cause hair to stand up more than usual. This may have made the early hairier people look bigger and help them scare off any animals or other people that might be attacking them. It also may have helped keep them warm because the fluffed hair may have trapped a layer of air close to the skin, which would stay warm from body heat while the air around the body was cold.