WHEN Barack Obama sought his African roots, he had it easy: his father came from Kenya’s . For most African Americans, the quest is more daunting – and the debate over the value of the genetic tests used by companies to connect black Americans to particular ancestral homelands just got more intense.
To map the genetic diversity of Africans, Sarah Tishkoff of the University of Pennsylvania in Philadelphia and her team studied about 2400 people from all across Africa, documenting the variation in 1327 genetic markers spread across the genome. They also sampled African Americans living in Chicago,…
