The non-voluntary removal or cutting of hair is known in most cultures. Hair may be removed with good intentions for medical treatment, or surgery, or may result, in some cases, from chemotherapy. It is commonly done for cosmetic purposes. Scalp and facial hair is removed from men entering boarding schools, military training or prisons, primarily to reduce possibilities of contagious scalp infection, although there are elements of initiation rites are also present. There are advantages in some sports: martial arts, swimming and wrestling and in some occupations: mining and milling. Shaving heads has also be used for penal purposes.