Ten years ago,while at the University of Western Australia,anthropologist Nina Jablonski was asked to give a lecture on human skin.As an expert on primate evolution,she decided to discuss the evolution of skin color,but when she went through the literature on the subject she was dismayed.Some theories advanced before the 1970s tended to be racist,and others were less than convincing.White skin,for example,was reported to be more resistant to cold weather,although groups like the lnuit(Eskimos)are both dark and particaularly resistant to cold.