Asked by: Amanda Hart, Cardiff
Men grow beards because the hair follicles on their jaw are stimulated by the hormone dihydrotestosterone (DHT), which is produced from testosterone.
Women have the same number of follicle cells on their faces as men, but these are less sensitive to DHT, and females also have lower testosterone levels to begin with.
Beards may have evolved as a signal of the testosterone levels of a man, and women came to find thicker beards attractive because it implied that their owner would be stronger or more dominant.
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