The "Out of Africa" theory that modern man evolved there and spread across the world got a boost today with new research tracing humans from diverse ethnic and geographical backgrounds back to the African continent. Swedish scientists used mitochondrial DNA--genetic material within cells that is passed unchanged from mother to child--from 53 people to show that the human evolutionary tree is firmly rooted in Africa.
Previous studies reaching the same conclusion have been criticized because researchers used only parts of the mitochondrial DNA. Researchers at the University of Uppsala report in today's Nature that they used the entire mitochondrial genome and confirmed previous results.
