Ancient stone artifacts recently excavated from Saudi Arabia possess similarities to items of about the same age in Africa -- a discovery that could provide clues to how humans dispersed out of Africa, researchers say.
Modern humans originated about 200,000 years ago in Africa. However, scientists have long debated when and how the modern human lineage spread out of Africa.
"Understanding how we originated and colonized the world remains one of the most fascinating and enduring questions, because it is our story as humans," said lead study author Eleanor Scerri, an archaeologist at the University of Bordeaux in France.
Previous research had suggested that the exodus from Africa started between 70,000 and 40,000 years ago. However, a genetic analysis reported in April hinted that modern humans might have begun their march across the globe as early as 130,000 years ago, and continued their expansion out of Africa in multiple waves.
In addition, stone artifacts recently unearthed in the Arabian Desert date to at least 100,000 years ago. This could be evidence of an early modern-human exodus out of Africa, scientists say. However, it's possible that these artifacts weren't created by modern humans; a number of now-extinct human lineages existed outside Africa before or at the same time when modern humans migrated there. For instance, the Neanderthals, the closest known extinct relatives of modern humans, lived in both Europe and Asia around that time. [See Images of Our Closest Human Ancestor]