In humans, the pilomotor reflex leads to the response commonly known as goose bumps, and this response is widely considered to be vestigial – that is, something formerly having a greater physiological advantage than at present. It occurs when the tiny muscle at the base of a hair follicle contracts, pulling the hair upright. In animals with feathers, fur, or quills, this creates a layer of insulating warm air or a reason for predators to think twice before attacking. But human hair is too puny to serve these functions. Goose bumps in humans may, however, have acquired a new role. Like flushing – another thermoregulatory (heat-regulating) mechanism – goose bumps have become linked with emotional responses, notably fear, rage, or the pleasure of, say, listening to beautiful music. They may thus serve as a signal to others.