|MadSci Network: Evolution|
In general, one could surmise that paleolithic human skin tone was related to sunlight intensity; those individuals who were able to better withstand prolonged or intense UV radiation at the equator because of denser melanin expression were more likely to successfully procreate, etc., etc. I'm not aware of any research attempting to follow the "evolution" of skin tone, however. The fat storage issue is complex. Paleolithic humans tended to be a nomadic bunch for many reasons, including (but certainly not limited to): 1) It got really cold in certain areas in the winter (forget Chicago-- let's try to imagine why anyone would live in International Falls, Minnesota!); 2) Many large mammals (meat sources) went south for the winter; and 3) Plant food sources died or were inaccessible during the winter. The fact that humans were generally adaptable to fluctuating food resources, understood the seasonal round and its effect on weather and food resources, and had some level of clothing to protect themselves suggests to me that if it started getting cold wherever they were, they'd just pick up and walk south. It's hard for me to imagine any significant portion of what was a very dispersed nomadic human population being subject to so much population pressure that they were forced to perish in a lethally cold environment. Once agriculture comes along, of course, we start setting up permanent settlements and attempting to store food. Once this system becomes the norm, it would certainly be possible to succumb to the combined effects of a food shortage, severe weather, and a lack of body fat.
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