Hyrtl states that the name labia was first used by Haller in the middle of the eighteenth century in his Elements of Physiology, being adopted by him from the Greek poet Erotion, who gave these structures the very obvious name χειλεα, lips. But this seems to be a mistake, for the seventeenth century anatomists certainly used the name "labia" for these parts.
Bergh tentatively suggests, as regards the pubic hair, that its appearance may be due to the upright walk in man and the human position during coitus, the hair preventing irritation of the genitals from the sweat pouring down from the body and protecting the skin from direct friction in coitus. (In both these suggestions he was, however, long previously anticipated by Fabricius ab Aquapendente.) The fanciful suggestion of Louis Robinson that the pubic hair has developed in order to enable the human infant to cling securely to his mother is very poorly supported by facts, and has not met with acceptance. It may be mentioned that (as stated by Ploss and Bartels) the women of the Bismarck Archipelago, whose pubic hair is very abundant, use it as a kind of handkerchief on which to clean their hands.
Routh and Heywood Smith have noted that the pubic hair tends to lose its curliness and become straight in women who masturbate. (British Gynæcological Journal, February, 1887, p. 505.)