Cosmetic and medical causes of hair weathering

To experts in any aesthetic field, scalp hair has 'life'. But in any scientific sense it is a dead structure made up of highly organized and orientated keratinized fibres and fibrils; and these can be modified by cosmetic procedures to give a seemingly infinite variety of beautiful and exciting styles. As the hair grows away from the scalp it degenerates or 'weathers' to some degree and this can be exaggerated by physical and chemical procedures such as overzealous brushing, bleaching, permanent waving and tricotillomania.