An international team of genetic researchers from the United States and Europe has found new evidence that there was an Ice Age refugium in southern Arabia.
Spatial frequency distribution map of haplogroup R0a. Image credit: Francesca Gandini et al.
Once the Ice Age receded — with the onset of the Late Glacial period about 15,000 years ago — the people of the refugium dispersed and populated Arabia and the Horn of Africa, and might also have migrated further afield.
The view used to be that people did not settle in large numbers in Arabia until the development of agriculture, around 10,000-11,000 years ago.
Now, the new findings demonstrate that modern humans have dwelt in this territory for far longer than previously thought.
The findings are based on a study of a rare mitochondrial DNA lineage, led by Dr. Francesca Gandini from the University of Huddersfield, UK, and are published in the journal Scientific Reports.
Dr Gandini and co-authors studied haplogroup R0a, which uniquely is most frequent in Arabia and the Horn of Africa, but is distributed much more widely, from Europe to India.
They reached the conclusion that this lineage is more ancient than previously thought and that it has a deeper presence in Arabia than was earlier believed.
This makes the case for at least one glacial refugium — perhaps on the Red Sea plains — during the Pleistocene period, which spanned the Ice Age.
The scientists also found that: “the main episode of dispersal into Eastern Africa, at least concerning maternal lineages, was at the end of the Late Glacial, due to major expansions from one or more refugia in Arabia.”
“There was likely a minor Late Glacial/early postglacial dispersal from Arabia through the Levant and into Europe, possibly alongside other lineages from a Levantine refugium.”
Moreover, according to the team, there might also have been a trading network and a ‘gene flow’ from Arabia into the territories that are now Iran, Pakistan and India.
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Francesca Gandini et al. 2016. Mapping human dispersals into the Horn of Africa from Arabian Ice Age refugia using mitogenomes. Scientific Reports 6, article number: 25472; doi: 10.1038/srep25472
