人感到冷或者害怕的时候,身体上自然而然会生出鸡皮疙瘩。鸡皮疙瘩的学名叫毛发直立。每个体毛根部的微小肌肉结合在一起,看起来就像人体上生出的一个个小疙瘩。在很久很久以前,人类还拥有天然“皮大衣”的时候,鸡皮疙瘩就具有实际意义。毛发变蓬松后,毛发之间的空气相当于一层绝缘体,给身体保温。竖起毛发对食肉动物或敌人来说是 When people are cold or scared, they naturally give goose bumps to their body. The scientific name of goose bumps is hair upright. The tiny muscles at the base of each body hair bind together and look like small lumps on the human body. A long, long time ago, when humans also had natural “fur coats,” goose bumps had real meaning. After the hair becomes fluffy, the air between the hair is equivalent to a layer of insulation, to the body insulation. It is for carnivores or enemies