Published online by Cambridge University Press: 24 August 2009
The suggestion is made that Man evolved orthograde posture and bipedal locomotion at the fringe of tropical forest rather than in open savanna. The primary adaptive function of bipedal locomotion was for walking and stalking game from the cover of trees, in the absence of undergrowth. Hairlessness was thermally advantageous when Man emerged from the trees, yet would have imposed no great hardship on our hominid ancestors while they were inside the forest, where the climate was constantly warm. Man's primitive skin-colour was probably pale-brown. It is thought that dark skins were later acquired primarily as a protection against ultraviolet radiation in tropical regions, whereas depigmentation occurred as an adaptation that enhanced the synthesis of calciferol in regions of low light-intensity.
Man's so-called ‘racial’ adaptations occurred when his scavenging and hunter-gathering technology was unable to counter natural selection. Recently, however, he has ceased to respond to environmental feed-back. Unless he begins to do so again soon, degradation of the environment may accelerate beyond the point of no return and our species be doomed.