Culturally speaking, ancient East Africans were a stone’s throw away from southern Arabia.
Stone tools collected at several sites along a plateau in Oman, which date to roughly 106,000 years ago, match elongated cutting implements previously found at East African sites from around the same time, say archaeologist Jeffrey Rose of the University of Birmingham, England, and his colleagues. New finds also include cores — or rocks from which tools were pounded off with a hammer stone — that correspond to East African specimens, the researchers report online November 30 in PLoS ONE.
East African sites that have yielded these distinctive stone artifacts extend southward along the Nile River to the Horn of Africa.
“In the mountain of papers speculating about human dispersal out of Africa, a link between southern Arabia and the Nile Valley has never been considered,” Rose says.
Either Africans crossed the Red Sea and trekked into southern Arabia well before an African exodus around 60,000 years ago, or ancient people from Arabia influenced African toolmaking, the scientists suggest.
“The finds in Oman are rather spectacular,” comments archaeologist Michael Petraglia of the University of Oxford, England. “They have a date that is earlier than similar African artifacts, which could imply a migration back to Africa, or at least a flow between African and Arabian populations.”
Although human fossils haven’t turned up at the Arabian location or at related African tool sites, Homo sapiens bones date to as early as 195,000 years ago in East Africa.
It’s unclear whether ancient Oman toolmakers continued eastward to South Asia or stayed put. Their distinctive toolmaking style doesn’t appear at Indian sites dating to around 74,000 years ago, Petraglia says.
Rose sees similarities between the Oman tools and 50,000-year-old stone implements previously excavated in and around modern-day Israel. He speculates that plentiful rainfall between 60,000 and 50,000 years ago made inner parts of Arabia habitable and enabled people in southern Arabia to spread northward and influence toolmaking techniques.
The new discoveries in Oman add to evidence that people reached Arabia’s east coast as early as 125,000 years ago (SN: 2/26/11, p. 5) and a northern inland area by 75,000 years ago.
At least two culturally distinct human groups inhabited Stone Age Arabia, Rose suspects: one in the south and another in the north and east. Intriguingly, DNA studies indicate that people interbred with Neandertals soon after leaving Africa (SN: 6/5/10, p. 5). An ice age between 75,000 and 50,000 years ago may have driven people and Neandertals into parts of Arabia that still had water sources, where interbreeding probably occurred, Rose hypothesizes.
The stone tools found at Oman, and those found at Arabia’s two other early H. sapiens sites, display few similarities, in Petraglia’s view. “This must mean that the story of migration and survival, and out-of-Africa dispersals, is much more complex than we have imagined,” he says.