Why do people get goosebumps when they are cold?

This is an experience that everyone has had. When the weather is cold and the clothes on your body are not warm enough, you will not only feel cold, but also shiver all over. And there will be goosebumps on the skin. This is because in addition to protecting our internal organs and excreting sweat, human skin can also regulate and maintain body temperature. When the skin is stimulated by cold, the sensory cells under the skin will immediately notify the brain, making the person feel cold. At the same time, the arrector pili muscles under the hairs will contract, making the hairs stand up. At this time, the surface of the skin becomes very tight, forming a protective wall to prevent the loss of body heat. When the arrector pili muscle contracts, it pulls the hair root, causing the hair to stand upright. When you want to straighten the hairs, you will pull up a piece of skin, forming small bumps that look like chicken skin with the hair removed, so they are called goosebumps. Goosebumps are a manifestation of the skin's self-defense function. It reminds people to "keep warm and be careful of getting cold." At this time, you should take measures to keep warm immediately to avoid catching a cold.

People not only get goosebumps when they are cold, but sometimes when they hear harsh sounds or see disgusting and scary things, their hair will stand on end and goosebumps will appear on their bodies.

Goose bumps have an obvious self-protective function for animals covered with long hair. When these animals get cold, their soft fur stands up, making the fur fluffy and keeping them warm and cold-proof. The ancestors of humans, the ancient apes, were also covered in hair. During the evolution of humans, body hair has gradually degenerated, but the physiological function of making goose bumps to protect against the cold has continued to be retained.