Goosebumps occur in mammals as a forced reflex called piloerection. In certain situations, hormones lead to hair erection.
Over time, people have evolved and thus the skin hair became thicker. When the temperature falls or you feel overwhelmed with excitement or other strong emotions it is likely that you’ll experience goosebumps. However, this never happens with the hair.
Goosebumps are affected by various stimuli, such as coldness, fear or strong emotions – something awe-inspiring or, for example, sexual arousal.
These stimuli cause the reaction of the sympathetic nervous system that “responds” to the unconscious stimulants. The sympathetic nervous system is reflected in the contraction of the arrector pili muscles that create goosebumps.
Moreover the hair follicles rise above the skin and cause goosebumps. This reflex occurs in a large number of mammals. The main reason for this phenomenon occurs at the subconscious level of the effects of the stress hormone – adrenaline.