Where did the term goosebumps come from?
Goosebumps, duckbumps, goosepimples – they’re all a warm-blooded animal’s way to involuntarily insulate its body from the cold. Although mammals and birds vary their activities greatly, their internal body temperature is relatively stable within a 2° C range. Mammals usually are between 36° and 38°C (humans are 37°C) while birds fall between 40° and 42°C. These warm-blooded animals maintain their body temperature, regardless of the weather, using the heat produced by normal cell and muscle activity.
The most important function of mammalian hair is the retention of heat. Air is an excellent insulator. Hair traps air between the skin and the environment, preventing cold air (or water) from reaching the skin and robbing the animal of its heat.
In birds, feathers serve the same purpose. Feathers provide excellent protection from the cold and the use of down-filled articles of clothing is based on feathers’ insulating properties. As with mammals, feathers also provide protection for birds living in a wet environment and serve to keep the water away from the skin.