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Africa climate history.
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[QUOTE]Originally posted by rasol: [QB] Solar Activity and Ice Ages, causes and relevance to African morphology. There are 3 principal factors directly effecting the amount of energy the earth gets from the sun. The solar cycle, orbital eccentricity and, perhaps the most important... orbital tilt. [IMG]http://www.museum.state.il.us/exhibits/ice_ages/images/tilt_graph.gif[/IMG] The greater the tilt in the Earth's axis.....the MORE solar energy is received in the mid and high latitudes....and less (than usual) is received in the tropical and equatoral regions. The smaller the tilt in the Earth's axis...the more solar energy is received in TROPICS, and less in the mid and high latitudes. It is this condition that is one of many interrelated culprits in triggering ICE AGES. 25 thousand years ago the Earth's axis tilt was near it's minimum. This means Northern EurAsia may have recieved less UV at this time, but tropical East Africa may have actualy recieved more. Pale skin tones developed in Eurasia at around this time. In tropical Africa, pale skin is and always has been maladaptive (ie = skin cancer). Native tropical Africans have dark skin for this reason and always have- throughout the [b]entire history of modern human evolution[/b] from 150kbp until today. [/QB][/QUOTE]
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