Races of man / by Sonia Cole.

  • Sonia Mary Cole
Date:
1965
Catalogue details
    26/150 page 21
    Helical and spiral hair might have spread from a single centre; more probably it arose in different parts of the tropical belt by parallel mutations. Outside Africa, spiral hair occurs among pygmies in the forests of Malaya, Sumatra, New Guinea and the Philippines as well as among the tall Papuans and Melanesians. Hair form is apparently controlled by a large number of genes, which makes it probable that a great many mutations have occurred. In Negro-White crosses, the Negroid traits of skin colour and hair form are apparently inherited inde pendently. Straight, coarse Mongoloid hair seems to be dominant over woolly hair, while fine, straight Caucasoid hair is recessive. Although there is probably an advantage in woolly hair as a protection for the scalp in strong sunlight, and to a certain extent curly hair would also be advantageous in this way, there seem to be no obvious advantages or disadvantages in straight or wavy hair. Hair colour depends on the black or brown granular pigment identical with that in the skin. In albinos this pigment is absent. In the case of blond hair the pigment is usually confined to the middle layer or cortex of the hair shaft; but in black hair the inner part or medulla is also full of melanin. In addition to melanin, a red acid-soluble pigment known as trichosiderin is sometimes present (Barni- cot, 1956). The mechanism of inheritance of red hair is probably genetically simple, while the inheritance of other kinds of pigmentation of hair seems to be complicated. Hair colour cannot be explained on climatic grounds as easily as skin colour. Although blondness is mainly confined to northern Europe and to migrants from this area, the Monogoloids of the coldest parts of Siberia or Greenland have hair as black as those living in the tropics. Development of beard and body hair also varies considerably among the races, It is strongest among 'archaic Whites' such as the Australian aborigines and Ainu, as well as among the Caucasoids, and is least developed among Negroids and Mongoloids. Eye Colour and Form Eyes are classified as light, mixed, brown or black. Blue (light) eyes are generally recessive to brown, the commonest colour. Eye colour sometimes darkens with age and there seems to be some sexual difference: women tend to have darker eyes than men of the same race and age. The black Negro eye is due to the density of pigment in the outer layer of the iris, while the brown eye colour of lighter-skinned races is mainly due to pigment
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