Decoded DNA Reveals African Diversity    Some Africans living within walking distance of one another are more genetically diverse than a European and an Asian living a continent apart.   Wed Feb 17, 2010 03:01 PM ET  content provided by Malcolm Ritter, Associated Press    THE GIST:  •Decoded DNA of southern Africans has revealed unexpected genetic diversity.  •Two bushmen living within walking distance show more genetic variation than a European compared to an Asian.  •The study also found 1.3 million tiny variations that hadn't been observed before in any human DNA. --------------------------------------------------------------------------------   Scientists who decoded the DNA of some southern Africans have found striking new evidence of the genetic diversity on that continent, and uncovered a surprise about the ancestry of Archbishop Desmond Tutu.   They found, for example, that any two bushmen in their study who spoke different languages were more different genetically than a E...