Australopithicus africanus: The evolving picture
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These two artist's reconstructions show differing conceptions of A. africanus. The painting on the left, from the 1960's, is incorrect, for it depicts a creature who is imperfectly upright, stands on chimp-like feet (which would simply not serve for efficient bi-pedal locomotion), and carries its skull forward on its spine like a chimp or gorilla. The recent depiction below right
is anatomically correct, based on current knowledge: A. africanus was efficiently bi-pedal and upright, and the posture suggested by the alignment of skull and spine is like our own. This family group--a nuclear family, apparently, and not the extended kinship group which would most probably have characterized the life-style of this species--is also shown as dark-skinned and relatively hairless. These features are educated guesses based on two considerations: first, to walk and run upright efficiently in open country near the Equator, hominids would have to have an efficient heat diffusion system to prevent their being overcome, or perhaps even killed, by the chemical heat caused by extended muscular exertion. At some point, then, the ancestors of modern humans evolved a skin like our own which acts as a cooling system. Water is evaporated on the surface of the skin and this cools the blood near the surface. To work effectively, the skin has to be naked. To survive under Africa's equatorial sun, a naked skin would have to be protected by a considerable amount of melanin, the dark pigment which protects tissue from ultraviolet light.