Body & HealthFact
Goosebumps are a program for fur you don't have.
Every hair has a tiny muscle attached, the arrector pili. In cold or fear it contracts and raises the hair. In furred animals this traps an insulating layer of air or makes them look bigger. On you, only the bump around a thin hair remains, a relic of millions of years of evolution.
Useful: That music can give you goosebumps shows how tightly emotion and the cold reflex are wired together.
Source: en.wikipedia.org