We get goose bumps when it's cold. That's to make the hairs erect and create a layer of insulation. Then why

Question

do nipples react when it's cold? What's the purpose? We shiver to create heat. There must be a reason for the nipples to erect right.

Answer 1

Cold stimulates a sympathetic system response, to save heath....all the muscle thet pull the hait erect, are smooth involuntary muscles, are innervated by the sympathetic (the same applies to the smooth involuntary circular muscles of the nipples)....cold is the main triggering, however fear or anxiety can cause the same effect, and sexual arousal in women (nipple smooth muscle).....There is not set "purpose for the contracin, just an stimulus, and a response,,,,,

Answer 2

Nipples are glorified hair folicles serving a different purpose now, but retaining remnants of their genetic history.