Ordinarily secretion of melanin in hair is taking place all the time simultaneously with the growth of hair. Some cells making this pigment die as the age advances. In other words, these cells become inactive. As they cease secretion of melanin in newly hair, the hair becomes almost transparent. However, hair appears white because of existence of some black hair in the background. Entire shock of hair on the head or face does not become colorless all of a sudden. Even after all the hair has become colorless gradually over a period of time, tufts of hair bunched together do not allow light to pass through. So in spite of being colorless individually, tufts of hair appear white collectively. Hair of apes like chimpanzee, gibbon, orangutan, gorilla etc who as primates are close relatives of human beings, also become white.