Hair care
Scalp hair grows, on average, at a rate of about 1.25 centimeters per month, and shampoos or vitamins have not been shown to noticeably change this rate. Hair growth rate also depends upon what phase in the cycle of hair growth one is actually in; there are three phases. The speed of hair growth varies based upon genetics, gender, age, hormones, and may be reduced by nutrient deficiency (i.e., anorexia, anemia, zinc deficiency) and hormonal fluctuations (i.e., menopause, polycystic ovaries, thyroid disease).
Hair theft
Hair theft has been a recurrent problem in various parts of the world where human hair is in demand either for commercial products such as wigs and hairpieces, or for sexual fetishes. As hair has a high commercial value – in the mid-19th century it was regarded as worth twice its weight in silver – opportunist thieves have targeted long-haired women, and less commonly men and children, with the aim of stealing their hair. Hair thieves have typically sought either to surreptitiously cut off hair in public places, or have mugged people and shorn their heads. The crime of hair theft has been widely reported in North America, Europe, Asia and Australasia over the course of at least 300 years.