Wednesday, September 21, 2016

How We Got Here: DNA Points to a Single Migration From Africa

The question of where humans came from has been one of the biggest in science for years. Three separate teams of geneticists from different places, all sampling different people, sequenced the genomes of 787 people from hundreds of different populations and found that all humans came from a single population from Africa between 50,000 and 80,000 years ago. The genomes were taken from a variety of people from every continent and were examined separately to finally come up with the same conclusion as to where people came from. Before now, there were very few sequenced genomes from people outside of population centers like China and Europe, but this new data with genomes from indigenous populations adds great value to our understanding of human DNA. 

The first team was Dr. Willerslev and a few colleagues who first sequenced the genome from a century-old lock of hair of an Aboriginal Australian. The results raised many questions, so the group joined David W. Lambert and the University of Oxford to obtain DNA from people from Papua New Guinea and from Aboriginal Australians to sequence. Mait Metspalu from the Estonian Biocentre sequenced genomes mostly from populations from Europe and Asia.  David Reich and his team from Harvard Medical School formed their database of genomes from people from all six inhabited continents. All coming up with the same results, the teams each established that there was an exodus from Africa 80,000 to 50,000 years ago, resulting in the populations we have today. There is also evidence of other groups migrating from Africa much earlier than 80,000 years ago, but these groups have since disappeared, having been wiped out by others who came after them who were stronger in number or in technology. 

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