BOSTON--Trading on the Pacific's high seas may have begun 2500 years earlier than archaeologists have thought, according to an analysis of volcanic glass shards presented here at the annual meeting of the Materials Research Society. The findings suggest that Neolithic peoples in the southwest Pacific set up what would have been the world's longest Stone Age trading route.
Two years ago, Steven Chia of the Universiti Sains Malaysia in Penang began excavating an archaeological site known as Bukit Tengkorak on the island of Borneo. Chia unearthed from under a rock shelter some 200 flecks of obsidian, a natural volcanic glass once hoarded for use in cutting tools, that were embedded in soil layers dating to 4000 years B.C. Because there are no known obsidian sources near the excavation site, the researchers were eager to see if they could trace the flecks' origin.
Chia and Robert Tykot, an archaeologist and chemist at the University of South Florida, analyzed the amounts of 11 different compounds, such as potassium oxide and silicon dioxide, in the Bukit Tengkorak obsidian flecks. They found that the majority of flecks had a chemical fingerprint matching well-known obsidian sources some 3500 kilometers away, near the island of New Britain and the Admiralty Islands. A smaller percentage came from a closer source near the Philippines. This "is the surviving evidence of what was almost certainly the longest Stone Age trade route," says Tykot.
Scientists had previously believed that sea trading in the southwest Pacific began about 1600 B.C. with the rise of the Lapita, a culture of seafarers who developed trade routes spanning islands stretched out over thousands of kilometers. Now it appears the Lapitas were Johnny-come-latelies to maritime commerce. "It looks like they have good evidence of distinct chemical fingerprints," says Ron Hancock, an analytical chemist and archaeologist at the University of Toronto. These fingerprints, he says, "give good credibility to the story" that Pacific sea trading indeed had a much more ancient history.