Why do we get Goose Bumps when it is cold?
Goose bumps are a heritage from the days when humans were covered
When it's hot and you need to cool down, little muscles at the
base of each hair relax. Your hair becomes relaxed. Your sweat
glands pump out body heat in sweat. Your blood vessels get big
to take more heat to the skin to get rid of it. When it's cold,
the arrector muscle pulls the hair up. The duct to the sweat glands
gets small to conserve heat. Our blood vessels also get small to
Hair standing up doesn't make very good insulation - we don't have
enough fur for that. Humans don't have very much hair on their bodies
anymore. Millions of years ago, humans probably did. And that hair
standing on end helped keep people warmer. Those little muscles we
have on the end of each hair still work. They still make goose bumps.