A short history of nearly everything - Bill Bryson [228]
In the 1940s a Harvard paleontologist named Hallum Movius drew something called the Movius line, dividing the side with Acheulean tools from the one without. The line runs in a southeasterly direction across Europe and the Middle East to the vicinity of modern-day Calcutta and Bangladesh. Beyond the Movius line, across the whole of southeast Asia and into China, only the older, simpler Oldowan tools have been found. We know that Homo sapiens went far beyond this point, so why would they carry an advanced and treasured stone technology to the edge of the Far East and then just abandon it?
“That troubled me for a long time,” recalls Alan Thorne of the Australian National University in Canberra. “The whole of modern anthropology was built round the idea that humans came out of Africa in two waves—a first wave of Homo erectus, which became Java Man and Peking Man and the like, and a later, more advanced wave of Homo sapiens, which displaced the first lot. Yet to accept that you must believe that Homo sapiens got so far with their more modern technology and then, for whatever reason, gave it up. It was all very puzzling, to say the least.”
As it turned out, there would be a great deal else to be puzzled about, and one of the most puzzling findings of all would come from Thorne's own part of the world, in the outback of Australia. In 1968, a geologist named Jim Bowler was poking around on a long-dried lakebed called Mungo in a parched and lonely corner of western New South Wales when something very unexpected caught his eye. Sticking out of a crescent-shaped sand ridge of a type known as a lunette were some human bones. At the time, it was believed that humans had been in Australia for no more than 8,000 years, but Mungo had been dry for 12,000 years. So what was anyone doing in such an inhospitable place?
The answer, provided by carbon dating, was that the bones' owner had lived there when Lake Mungo was a much more agreeable habitat, a dozen miles long, full of water and fish, fringed by pleasant groves of casuarina trees. To everyone's astonishment, the bones turned out to be 23,000 years old. Other bones found nearby were dated to as much as 60,000 years. This was unexpected to the point of seeming practically impossible. At no time since hominids first arose on Earth has Australia not been an island. Any human beings who arrived there must have come by sea, in large enough numbers to start a breeding population, after crossing sixty miles or more of open water without having any way of knowing that a convenient landfall awaited them. Having landed, the Mungo people had then found their way more than two thousand miles inland from Australia's north coast—the presumed point of entry—which suggests, according to a report in the Proceedings of the National Academy of Sciences, “that people may have first arrived substantially earlier than 60,000 years ago.”
How they got there and why they came are questions that can't be answered. According to most anthropology texts, there's no evidence that people could even speak 60,000 years ago, much less engage in the sorts of cooperative efforts necessary to build ocean-worthy craft and colonize island continents.
“There's just a whole lot we don't know about the movements of people before recorded history,” Alan Thorne told me when I met him in Canberra. “Do you know that when nineteenth-century anthropologists first got to Papua New Guinea, they found people in the highlands of the interior, in some of the most inaccessible terrain on earth, growing sweet potatoes. Sweet potatoes are native to South America. So how did they get to Papua New Guinea? We don't know. Don't have the faintest idea. But what is certain is that people have been moving around with considerable assuredness for longer than traditionally thought, and almost certainly