The function of human hair is, curiously, unresolved. Hypotheses vary: Is it a relic of the hypothetical aquatic phase of human development where a pelage would be an impairment? Is hair an integral adaptation for thermoregulation and ultraviolet protection, a mere adornment, or the result of Fisherian runaway sexual selection? All these theories can be disproved not least by the tendency for humans of both sexes to bald.
Hair may and often is interpreted as a marker of age, healthy nutrition, and fecundity. In its styled form it is employed in all societies to express social status or cultural affi liation. Hair in most cultures is at its zenith on the wedding day as a mark of health, wealth, and sexual attraction. By contrast, sociological studies have revealed the full impact of so-called bad hair days, where subjective and objective negative assessment of hair may reduce self-esteem.
