Great genetic differences among South Africans
Thomas Maugh II in the LA Times:
Scientists have long known that natives of southern Africa are genetically quite distinct from people in the rest of the world, but a new study in which the genomes of four African Bushmen and one Bantu were sequenced or partially sequenced indicates that there is a much greater diversity among the populations there than had previously been suspected.
Two Bushmen from different tribes living within walking distance of each other can have greater genetic differences than a European and an Asian, according to the study published in Thursday’s edition of the journal Nature.
"If we really want to understand human diversity, we need to go to Africa and study those people," geneticist and lead author Stephan Schuster of Pennsylvania State University said in a teleconference Wednesday.
The study, which marked the first time that the DNA of a hunter-gatherer had been sequenced, found about 1.3 million novel variants in the genetic sequences, accounting for about 1% of the total human genome, the researchers said.
The greater genetic diversity there, researchers said, probably results from the fact that modern southern Africans originated there and have lived continuously in one region much longer than other peoples, thereby having more time to accumulate variations. Despite those differences, the Bushmen also had similarities that distinguish them from other population groups. They were missing a gene that allows them to metabolize lactose; were lacking a gene that promotes malaria resistance; had genes that gave them denser bones, greater strength and a greater ability to run short distances; and had another gene that promotes their ability to retain salt and water at high temperatures.
Even so, the researchers said, it is important to remember that the overall genomes of all human beings are virtually identical and the small differences they observed represent adaptations to new or changing environments.
The research was conducted by …
