Scientists use genetics and climate reconstruction to track global spread of modern humans out of Africa

Scientists have developed a model to predict the routes taken by modern humans, H. sapiens, out of Africa 100 thousand years ago.  This model was published on September 17^th in PNAS (Proceedings of National Academy of Sciences).  “By combining extensive genetic information with climate and vegetation models, we were able to build the most detailed reconstruction of human history so far,” stated Dr. Anders Eriksson, the lead author of the paper and a professor at the University of Cambridge.  Using this reconstruction the scientists were able to determine the best routes for the early humans to take out of Africa.



During their study, the scientists considered climate change, food availability, birthrates, and many other factors that would influence a large scale movement of populations.  They determined that food availability, which was scarce in Northern Africa, prevented most movement out of the continent until a break in the cold weather came approximately 70-55 thousand years ago.  Most modern humans then traveled out of Africa via the Bab-el-Mandeb strait into the Arabian Peninsula.

The research presented by the scientists is supported by the fossil record, which was not actually used to generate the models.  There is, however, a major exception of Europe.  The scientists’ model predicts the presence of H. sapiens in Europe 10 thousand years prior to their appearance in the fossil record.  This discrepancy is most likely due to competition with Neanderthals at the time, which was not included in the models. The ability for scientists to combine all influencing factors to create a movement model for early humans is incredible, especially since they did not use the actual fossil record when creating their model.  It will be interesting to see if they will be able to find evidence of interactions with Neanderthals to back up their theory on delayed expansion into Europe.  I was expecting more information regarding the genetics portion of the study than what was actually in the article.