TABLE OF CONTENTS As social beings we communicate significantly via our physical appearance and so together with epidermal pigmentation the hair fibre-producing mini-organ accounts for most of the variation in the phenotype of different mammals and between different human population groupings. Although commonly dismissed as being of superficial importance, the hair follicle(s) (HF) is truly one of human biology's most fascinating structures. [1] Hair growth, one of only two uniquely mammalian traits (in addition to mammary glands), serves several important functions. These include thermal insulation, camouflage (melanin affords significant protective value, e.g. change of coat colour in the arctic fox with season), social and sexual communication (involving visual stimuli, odorant dispersal etc.), sensory perception ( e.g. whiskers), and protection against trauma, noxious insults, insects, etc. These features have clearly facilitated evolutionary success in animals, but it is not immediately clear how these may have proved critical for human survival. That said, one should not diminish the role of hair in social and sexual communications among humans. Because of our relative nakedness most attention and study is focused on scalp hair that, uniquely amongst primates, can be very thick, very long and very pigmented. Conversely, its absence from the human scalp can result in significant psychological trauma [2], e.g. in cases of androgenetic...
