On Australia's southern coast scientists have found a puzzle. Every explanation is so improbable it would be dismissed, were it not that the alternatives were just as strange. Among these unlikely options is the astonishing possibility humans reached Australia 55,000 years earlier than the oldest previously proposed dates. If true, it would not only overturn our thinking about the occupation of one continent, but the whole of human migration beyond Africa.
Forty-five years ago Professor James Bowler of the University of Melbourne made a discovery that was to change Australian archaeology. At Lake Mungo, New South Wales, he found the oldest human remains in Australia, proving humans had been in Australia for 40,000 years. Since then tools 25,000 years older have been found.
Yet Bowler's new site hints at a human presence 120,000 years ago. This is so contradictory to everything else we think we know about human migrations that Bowler acknowledges there will be plenty of resistance. Moreover, as Bowler noted to IFLScience, the site lacks tools or human bones. Yet Bowler and colleagues can offer no natural explanation for what they have found.
For tens of thousands of years the Gunditjmara people camped at Moyjil, near the mouth of the Hopkins River, for the access to food and fresh water. Beneath the oldest Gunditjmara remnants, blackened stones that appear to have got their color and fracturing from repeated exposure to fire, are eroding from the cliff face. Wildfire is a natural part of the Australian bush, but in six papers in a special issue of the Proceedings of the Royal Society of Victoria Bowler, Dr John Sherwood of Deakin University and Monash University's Professor Ian McNiven argue the pattern of blackening suggests a campfire rather than a bushfire.
Moreover, the site also contains remains of edible shellfish. The coastline hosts many similar shell middens. The distribution of species at Moyjil resembles those of human origin, and differs greatly from those left by birds. The papers consider several natural explanations for both fire and shells, but conclude evidence for these is inconclusive.
If the rock and shell-containing strata was more recent, no one would question its status as marking a human campsite, but Bowler has dated it to 120,000-125,000 years ago. Archaeological dating is often controversial, but Bowler is firm. “We've used several independent dating methods that all give the same result,” he told IFLScience.
Bowler is under no illusions how strange it would be to find a human presence so much older than anything else on the continent. “Who were they? Why here and not elsewhere? Why no legacy of any toolkit, no traces of food let alone human remains?” he wrote in one of the papers with Sherwood, Federation University's Dr Stephen Carey and Dr David Price of the University of Wollongong.
Bowler doesn't want to enter into discussions about which is less improbable, that Homo Sapiens left Africa so much earlier than we thought, or that another species of human, such as Homo Erectus, somehow reached Australia. Two years ago the possibility of early human species reaching America 130,000 years ago shook palaeontologists but the evidence could be explained in other ways. “I'm a geologist,” he told IFLScience. “I don't enter into such speculative areas, I have no idea who these people were.”
Nor does Bowler expect archaeologists to accept any human presence without signs of tools or human bones. He acknowledged that, when previous discoveries have pushed back the time of Australia's earliest occupation, they have done so incrementally, and “there has been continuity”. Moyjil is quite different. However, he added, sites of similar age have been ignored, since the possibility of humans in Australia prior to 70,000 years ago was unthinkable. Now perhaps, people will check, just in case.
This video reveals the context and beauty of the Moyjil site, but was made before the latest research revealing just how old the possible human occupation really is.
[H/T: The Guardian]