Researchers Find Error in African Genome Study

The authors of a scientific study that found Eurasian DNA in the African genome have announced an error in their original research.

The initial paper, which was published in October of 2015 in the journal Science, revolves around the 4,500 year old remains of an Ethiopian man found in Mota Cave who supposedly bore genetic markers of Eurasian descent. The scientists had thought this discovery lent additional credence to the hypothesis, put forward in a 2013 study, that a “reverse migration” back to Africa occurred approximately 3,000 years in the past. While the general hypothesis has not been disproved, evidence of it was recorded incorrectly in the Mota Cave remains due to a computer error.

The error, as explained by University of Cambridge geneticist and study co-leader Andrea Manica, was a result of software incompatibility between two programs used to reference human genetic material. Portions of the Ethiopian man’s genetics that he shared with Europeans were left out of the analysis, which made him seem to be more distantly related to Europeans than he was in actuality, while at the same time giving the impression that contemporary populations of Africans have a closer connection to Europeans through their DNA than they do. A software script designed to smooth out any errors generated by the two incompatible pieces of programming was not run, leading to the discrepancy.

In the end, this led the team to surmise that the so-called “genetic backflow” into Africa was more widespread than the evidence supports. East African backflow is widely considered to have occurred, but the data error showed false evidence of the reverse migration reaching into West and Central Africa as well.

In an interview with Scientific American, Harvard Medical School population geneticist Pontus Skoglund; part of the research team that checked the work of the original study, was heavy with praise for the initial paper. Remarking that “the genome itself is just fantastic”, he also applauded the willingness of the original scientists to not only share their data but to also respond to the revelation quickly in order to publish the error. Skoglund continued, remarking that the re-migration into East Africa is widely considered fact, and that the scientific community almost unilaterally agrees that Eurasian genetics did indeed flow back into East Africa, at the very least.

So far, Science has yet to announce if it will be publishing the update on the research. However, Manica did comment that if her team had caught the error before it had gone into print, the scientific findings would have been different on a fundamental level.

The initial article in its unaltered form, prior to discovering the error, can be found online here

Image courtesy of Wikimedia Commons user Russ London

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