New archaeological finds show that periods of increased rainfall transformed the Arabian Desert into a regular route for human migration over the last 400,000 years.
The study, involving archaeologists from Durham, gives a better understanding of the multiple human dispersal routes out of Africa via Arabia and into Eurasia.
The team discovered evidence for thousands of ancient lakes as well as stone tools left by humans in the Nefud Desert of Saudi Arabia. From this, they know that rainfall periodically transformed the region from one of the most uninhabitable places in that part of the world into a lush grassland that provided opportunities for repeated population movements.
While today the Nefud desert is a very arid region, it has experienced multiple periods of increased rainfall over the last 400 thousand of years, enough to create thousands of freshwater lakes.
These wetter periods, or so-called ‘Green Arabia phases’, provided enough water and food for early humans as well as animals such as elephants and hippos to move into the region. Once dry conditions returned, they would move into other areas and into Eurasia, making northern Arabia a crucial migration route and crossroads for early humans and fauna.
The wide range of stone tools discovered by the team also reveals changes in human culture over time.
Out of the six phases of lake formation found, five of them were associated with stone tools made by early humans at around 400, 300, 200, 100, and 55 thousand years ago.
Each of the phases of human occupation shows a distinct kind of material culture. This suggests that different populations, and potentially different hominin species, settled on the shores of these ancient lakes between 400 to 55 thousand years ago, putting Arabia on the global map for human prehistory.
The project is carried out by a large international consortium of scientists from different institutions in Europe, and led by the Heritage Commission of the Saudi Ministry of Culture and the Max Planck Institute for the Science of Human History in Germany.