Hair

Although we may not reach Rapunzel fame, the majority of us have a great deal of hair on our heads - 120,000 to be exact. These long 'shafts' of dead hair are composed of keratin, a strong fibrous protein, that grows from a living follicle. Given we are mammals, it is peculiar that we've lost so much hair but retained in certain regions. There are many theories regarding this, such as better thermoregulation, loss of parasites, and communicative purposes, but there is no definite answer.