A few months ago we blogged about the publication of the first genome sequence from an ancient African, in which the authors concluded that an ancient “back migration” of humans from the Middle East into Africa had left traces of Eurasian DNA in the genomes of Africans throughout the continent today.
As it turns out, the researchers made some mistakes when using certain computer software to analyze the genome data. After the study’s publication, another group of scientists reanalyzed the original data, which the study authors shared, and came to different conclusions: there is almost no sign of Eurasian DNA in the genomes of today’s western and southern Africans. The original authors have since confirmed the errors and promptly published a correction note. The conclusion that the genomes of today’s East Africans contain significant amounts of DNA that can be traced back to the peoples of Europe and Asia, who back-migrated into Africa after the lifetime of this ancient genome’s owner, remains correct. However, this migration did not reach too far beyond East Africa.
While the errors in the computer analysis could conceivably have been caught earlier, this incident is a good demonstration of the self-corrective power of the scientific process. It also highlights the importance for scientists to be open in sharing their data, so that other researchers can make use of them to advance science – and to catch the occasional mistake and correct the scientific record!