When humans migrated out of Africa 84,000 years ago, they did not only move across the Red Sea, as traditionally believed. New evidence suggests that some journeyed across the Sinai Peninsula and then followed rivers through the Rift Valley in Jordan as they made their way into Eurasia.
A secondary path out of Africa
Modern humans evolved in Africa between 200,000 and 300,000 years ago. They then spread across Asia and Europe in waves over tens of thousands of years. Previously, many experts believed that they made their way out of the continent using a southern route across the Red Sea.
“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,” said Paul Carling, a geomorphologist and one of the researchers.
Map A: The arrows indicate the suggested routes of human dispersals out of Africa. Map B: Digital elevation model map of the Levant showing the location of the study areas (yellow stars). Image: M Abbas et al., 2023
The new research points to a northern route. In Jordan’s Rift Valley, scientists uncovered some tools known as flakes scattered along the bank of the wadis (intermittent water channels). Using luminescence dating, the researchers were able to date the sediment that had buried the tools. This method estimates how long it has been since the sediment was exposed to light. The results suggest that early humans used the flakes 84,000 years ago.
A hand tool discovered in Jordan Rift Valley. Photo: University of Southampton
A time before the desert
At least some of our early ancestors made their way from Africa to Eurasia over land. The route out of Africa and across the Levant (modern-day Jordan, Israel, and Palestine) is the only land route to the north. Though it is now desert, at the time it was lush and green, providing everything humans needed for survival.
“Humans migrated using a northern route, using small wetland areas as bases whilst hunting abundant wildlife in the drier grasslands,” Carling said.
The study focused on three areas: along the Rift Valley and the Jordan Plateau, Wadi Gharandal, and Grega/Wadi Hasa. The team also used luminescence dating to decipher the environmental conditions of the time. These show a cycle between dry and wet periods. At some points, the Rift Valley acted as a 360km freshwater corridor.
Wadi Gharandal, a small wetland in the Jordan Rift Valley. Photo: Mahmoud Abbas
One of the most surprising findings was the importance of small wetlands to migrating humans. Older studies focused on larger lakes, but the smaller bodies of water acted as “staging posts.”
“As these wetlands occur along the margins of the Rift they allowed humans to use the Rift as a migration corridor out of Africa from as early as 123,000 years ago into Asia Minor and Sinai, with the potential to spread further into Europe and Asia,” Carling told The National.
While the purpose of the study was to provide evidence for a new route out of Africa, it highlights something equally as important — the role that climate plays in ancient human migrations.
