1. The reason why people get goosebumps when they are cold is that they can preserve body temperature.

2. Goosebumps are a unique physiological phenomenon of warm-blooded animals to preserve their body temperature. When the brain senses cold, tension or excitement, the sympathetic nerves will cause the arrector pili muscles of the body hair to contract, causing goose bumps. Goosebumps cause muscles to contract to generate heat and close pores to keep out the cold.