how do humans develop goose bumps when its cold or there is a temperature change?

Question: how do humans develop goose bumps when its cold or there is a temperature change?
- Keywords:
  cold,
  goosebump,
  temperature
Asked by itsspaigee to Amy, Karen, Sarah, Will on 20 Jun 2012.
- Sarah Martin answered on 20 Jun 2012:
  
  Hi itsspaigee!
  
  It’s a really old reaction we’ve inherited from the days when we had fur, and could make it stand up (like scared cats!), which would make it thicker and warmer! So each goosebump would have made fur hair stand up on our bodies, but we don’t have much left these days so we just have to put on a jumper and the goose bumps disappear again.
  
  Great question!
  🙂 Sarah
- Amy Birch answered on 20 Jun 2012:
  
  Hi itsspaigee,
  Goosebumps happen when your hair stands on end, this is to create a bigger surface of trapped air on top of your skin between all the hairs. This helps to stop some of the heat that would be lost out of your skin.

Question: how do humans develop goose bumps when its cold or there is a temperature change?