For this latest research, the team conducted fieldwork in the Jordan Rift Valley where they uncovered hand tools, known as ‘flakes’, on the edge of wadis – now dry river channels which, tens of thousands of years ago, were full of water. The scientists used luminescence dating techniques to help establish the age of the sediment the tools were buried in. This method estimates how long it has been since sediment was last exposed to light.
The results showed the tools were likely to have been used approximately 84 thousand years ago and then abandoned on the banks of the wadis and subsequently buried over time.
Paul Carling, Professor of Geomorphology at the University of Southampton, comments: “It’s long been thought that when the sea level was low, humans used a southern crossing, via the Red Sea from the horn of Africa, to get to southwestern Arabia. However, our study confirms there was a well-trodden passage to the north, across the only land-route from Africa to Eurasia.
“Our newly published evidence is a key piece of the puzzle that shows humans migrated using a northern route – using small wetland areas as bases whilst hunting abundant wildlife in the drier grasslands. Although previous studies have looked for large lakes as potential watering holes, in fact small wetlands were very important as staging posts during the migration.”
Dr Mahmoud Abbas, the study’s lead author from Shantou University, China, said: “The Levant acted as a well-watered corridor for modern humans to disperse out of Africa during the last interglacial, and we have now demonstrated this is the case in the Jordan Rift Valley zone.
“The paleohydrological evidence from the Jordan desert enhances our understanding of the environmental setting at that time. Rather than dry desert, savannah grasslands would have provided the much-needed resources for humans to survive during their journey out of Africa and into southwest Asia and beyond.”
The researchers say their study demonstrates the intimate relationship between climate change, human survival and migrations.