Army of GOD wrote:Hair is weird. Why do we have hair in oddly selective places (eg too of head, armpits, crotch)?
Off the top of my head (pun intended) I would say that hair follicles are also the sites of both the sebaceous glands (oil too lubricate the skin) and the sweat glands. These use the hair follicle and the hair to distribute the sweat effectively for maximum cooling effect.
Army of GOD wrote:Why can men grow fill beards but not women? Is that an evolutionary thing?
The sweat glands are driven by hormones, specifically those in greater quantities in males as opposed to females. This in turn drives the hair follicles in many areas of the skin.