Tough, adaptable modern humans could have forged into Asia at least 100,000 years ago and withstood Toba’s insults, agrees John Shea of Stony Brook University in New York. But stone points from Jebel Faya are shorter, thicker and less pointy than those found throughout Africa beginning 100,000 years ago, he says.
Similarities of Jebel Faya points to Indian finds suggest that the Arabian site could as easily reflect an ancient westward movement of Asians—possibly Homo sapiens from the Persian Gulf region—to Arabia, Shea proposes. So humans could have been migrating away from Asia, not toward it as argued in the new report. It’s more likely that warm, wet conditions around 100,000 years ago prompted dead-end migrations of modern humans into Arabia and the Middle East, argues Stanley Ambrose of the University of Illinois at Urbana-Champaign. Previously unearthed fossils from several Israeli caves indicate that modern humans moved from Africa to the Middle East approximately 100,000 years ago but—either because they died out or returned to Africa—gave way to Neandertals by 70,000 years ago.
Pollen evidence indicates that the Toba explosion set off 10,000 years of extreme cold and environmental devastation that nearly wiped out African Homo sapiens, Ambrose contends. Modern human survivors of the blast’s aftermath then colonized Asia, in his opinion.
Paul Mellars of the University of Cambridge agrees with that scenario. But like Shea, he sees critical size and shape differences between Jebel Faya and African stone tools, casting doubt on the African origins of the Arabian tool-makers. “These Arabian finds are too ambiguous to say what was happening with human movements out of Africa,” Mellars remarks.
If the Arabian discoveries indeed signal an early human migration to Asia, then excavations of Stone Age sites in Iran should produce similar tools, Shea predicts. Iran’s current political climate, however, makes such work difficult, he says.