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 sharing genes as well as information.”
The problem, as ever, is the fossil record. “Very few parts of the world are even vaguely amenable to the long-term preservation of human remains,” says Thorne, a sharp-eyed man with a white goatee and an intent but friendly manner. “If it weren’t for a few productive areas like Hadar and Olduvai in east Africa we’d know frighteningly little. And when you look elsewhere, often we do know frighteningly little. The whole of India has yielded just one ancient human fossil, from about 300,000 years ago. Between Iraq and Vietnam-that’s a distance of some 5,000 kilometers-there have been just two: the one in India and a Neandertal in Uzbekistan.” He grinned. “That’s not a whole hell of a lot to work with. You’re left with the position that you’ve got a few productive areas for human fossils, like the Great Rift Valley in Africa and Mungo here in Australia, and very little in between. It’s not surprising that paleontologists have trouble connecting the dots.”
The traditional theory to explain human movements-and the one still accepted by the majority of people in the field-is that humans dispersed across Eurasia in two waves. The first wave consisted of Homo erectus, who left Africa remarkably quickly-almost as soon as they emerged as a species-beginning nearly two million years ago. Over time, as they settled in different regions, these early erects further evolved into distinctive types-into Java Man and Peking Man in Asia, and Homo heidelbergensis and finally Homo neanderthalensis in Europe.
Then, something over a hundred thousand years ago, a smarter, lither species of creature-the ancestors of every one of us alive today-arose on the African plains and began radiating outward in a second wave. Wherever they went, according to this theory, these new Homo sapiens displaced their duller, less adept predecessors. Quite how they did this has always been a matter of disputation. No signs of slaughter have ever been found, so most authorities believe the newer hominids simply outcompeted the older ones, though other factors may also have contributed. “Perhaps we gave them smallpox,” suggests Tattersall. “There’s no real way of telling. The one certainty is that we are here now and they aren’t.”
These first modern humans are surprisingly shadowy. We know less about ourselves, curiously enough, than about almost any other line of hominids. It is odd indeed, as Tattersall notes, “that the most recent major event in human evolution-the emergence of our own species-is perhaps the most obscure of all.” Nobody can even quite agree where truly modern humans first appear in the fossil record. Many books place their debut at about 120,000 years ago in the form of remains found at the Klasies River Mouth in South Africa, but not everyone accepts that these were fully modern people. Tattersall and Schwartz maintain that “whether any or all of them actually represent our species still awaits definitive clarification.”
The first undisputed appearance of Homo sapiens is in the eastern Mediterranean, around modern-day Israel, where they begin to show up about 100,000 years ago-but even there they are described (by Trinkaus and Shipman) as “odd, difficult-to-classify and poorly known.” Neandertals were already well established in the region and had a type of tool kit known as Mousterian, which the modern humans evidently found worthy enough to borrow. No Neandertal remains have ever been found in north Africa, but their tool kits turn up all over the place. Somebody must have taken them there: modern humans are the only candidate. It is also known that Neandertals and modern humans coexisted in some fashion for tens of thousands of years in the Middle East. “We don’t know if they time-shared the same space or actually lived side by side,” Tattersall says, but the moderns continued happily to use Neandertal tools-hardly convincing evidence of overwhelming superiority. No less curiously, Acheulean tools are found in the Middle East well over a million years ago, but scarcely exist in Europe until just 300,000 years ago. Again, why people who had the technology didn’t take the tools with them is a mystery.
For a long time, it was believed that the Cro-Magnons, as modern humans in Europe became known, drove the Neandertals before them as they advanced across the continent, eventually forcing them to its western margins, where essentially they had no choice but to fall in the sea or go extinct. In fact, it is now known that Cro-Magnons were in the far west of Europe at about the same time they were also coming in from the east. “Europe was a pretty empty place in those days,” Tattersall says. “They may not have encountered each other all that often, even with all their comings and goings.” One curiosity of the Cro-Magnons’ arrival is that it came at a time known to paleoclimatology as the Boutellier interval, when Europe was plunging from a period of relative mildness into yet another long spell of punishing cold. Whatever it was that drew them to Europe, it wasn’t the glorious weather.
In any case, the idea that Neandertals crumpled in the face of competition from newly arrived Cro-Magnons strains against the evidence at least a little. Neandertals were nothing if not tough. For tens of thousands of years they lived through conditions that no modern human outside a few polar scientists and explorers has experienced. During the worst of the ice ages, blizzards with hurricane-force winds were common. Temperatures routinely fell to 50 degrees below zero Fahrenheit. Polar bears padded across the snowy vales of southern England. Neandertals naturally retreated from the worst of it, but even so they will have experienced weather that was at least as bad as a modern Siberian winter. They suffered, to be sure-a Neandertal who lived much past thirty was lucky indeed-but as a species they were magnificently resilient and practically indestructible. They survived for at least a hundred thousand years, and perhaps twice that, over an area stretching from Gibraltar to Uzbekistan, which is a pretty successful run for any species of being.