© Katerina Harvati/University of Tübingen and Senckenberg Center for Human Evolution and Palaeoenvironment
Landmarks shown in one individual cranium.
A team of European researchers is suggesting that humans dispersed out of Africa in multiple waves, rather than in just one, and that it occurred much earlier than has been previously thought. In their paper published in Proceedings of the National Academy of Sciences
, the group describes how they built migration models based on gene flow and skull characteristics to predict human migration out of Africa.
Scientists have generally agreed that humans first migrated out of Africa 40,000 to 70,000 years ago, culminating in settlements that span the globe. That estimate has been rocked in recent years however, by discoveries of stone artifacts in the Arabian Desert that date back at least 100,000 years (close to the time that modern humans were thought to have arisen). In this new effort, the researchers have expanded on the idea that humans may have left Africa sooner than most had thought, and that it likely happened via multiple routes, rather than just one.
The models the team built took into account genetic dispersal and human skull shape - they created four possible model scenarios of migration - two that showed a single path out of Africa and two that showed multiple paths. The first of the single migration paths involved people traveling north along the Nile valley then turning right when they hit the Mediterranean Sea. The second involved people meandering along the Arabian Peninsula until making their way to Asia. The multi-path migration models
involved people marching out of Africa along several paths, both north and south of the Arabian Peninsula.