In one of those moments you can only really have in the bath, I suddenly wondered the other day why we have hair (which made a change from my usual worrying about why I don't). A quick search on Google provided the following answer:
"At one time, it was believed that body and scalp hair is a useless evolutionary leftover from our primate past. At most, it was believed, hair may have some peripheral functions such as insulating our bodies from extremes of temperature. As our understanding of the human body increased-especially by applications of molecular biology that sees body functions in fine detail-we learned that the hair follicle plays a role in many processes involving the skin. We learned that the hair follicle is a source of stem cells that can be active in wound repair as well as in hair growth and regrowth. We learned that hair follicles can be a source of some types of skin tumors, and may be implicated in diseases of uncertain cause such as alopecia areata. And, of course, we learned how hair follicle function is intimately associated with whole-body systems such as genetic control of androgenic hormone production, thyroid gland responses to internal and external environments, and nutritional status. Hair follicle function is highly integrated with molecular signals to and from these whole-body systems."
Wow! Apparently hair is pretty useful...I'm starting to wish I hadn't asked.
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