Long hair is any hairstyle which is relatively long. Long hair has become a lifestyle an trend. Exactly what constitutes "long hair" can change from culture to culture, or even within cultures. For example, a woman with chin-length hair may be said to have short hair, while a man with the same length of hair would be said to have long hair. Scientists view long hair as playing a large part in any animal species' natural selection, since hair length is frequently a sign of health. Freudian psychoanalysts also see it in a sexual light, as a representation of the id's release from the suppression of the superego.