In the long history of science, there are few eureka moments. Sudden revelations are rare and science often progresses with Darwinian slowness. Even if they begin with a strikingly unusual hypothesis, most scientists set out to amass more and more data, as Darwin himself did, until they are confident their theories will stand the scrutiny of their peers.
These days, too, it is often teams of investigators who explore the frontiers of science and they may be based in institutions around the world. This is especially so for those searchers after buried intellectual treasure, the archaeologists, who need the patience of Job in their field work and sometimes the expertise of geologists, chemists and carbon-dating specialists as well.
Such is the case of an international team of archaeologists who found a piece of a stone axe in northern Australia and discovered its blade had been ground down thousands of years earlier than any similar object previously located.
The fragment, a mere four centimetres long, was dug up in a large rock-shelter in Jawoyn Aboriginal country in south-western Arnhem Land.
Dr Bruno David, a Monash University archaeologist and member of the team who made the discovery, says the axe fragment was so small it was missed among the natural small rocks during the digging. He only noticed it when he returned with the excavated sediments to Monash's archaeology laboratories.
"I emptied the bag full of rocks and sand from the layer we had been excavating and immediately saw the fragment in the tray in the laboratory," David says. "I put it aside on the edge of its proper tray to protect it."
Another member of the team is New Zealand scientist Dr Fiona Petchey who works at the Waikato Radiocarbon Dating Laboratory. Petchey prepared four pieces of charcoal, taken from just above and below where the axe fragment was found, and radiocarbon dated them at an accelerator mass spectrometer in America.
The carbon dating showed the fragment had been dropped in the shelter 35,500 years ago. This was far earlier than the previously oldest examples of ground-edge implements, dated at 34,000 to 26,000 years ago, found in Japan and elsewhere in northern Australia. Other carbon dates from levels below the axe fragment suggest the cave had been occupied by humans more than 45,000 years ago.
"The Jawoyn Association, representing the traditional owners of the country, had contacted us to begin archaeological research on their lands," David says. "We only had a few weeks available this year so we asked to start with a site that would not be very deep and they suggested the rock shelter, a dramatic-looking site that particularly interested them."
He says the 19-metre by 19-metre shelter has superb rock art and wonderful rock formations but parts are threatened by water buffaloes walking through. The Jawoyn people wanted to find out whether any important archaeological items were likely to be buried in the underlying sediments and, if so, to discuss measures that could be taken to protect them from the water buffaloes before it was too late.
"They are also interested in advice on cultural heritage management for their ecotourism ventures. They wanted to know if this would be an appropriate place to take visitors and, if so, what conservation issues should be considered in light of the site's archaeological potential," Dr David says.
"Selecting this site as the first of a long-term archaeology research project met all the objectives of the Jawoyn Association and Monash, with the aim of gradually building an understanding of the long history of Aboriginal occupation and use of Jawoyn country."
Following last year's preliminary excavations, David says the team plans to continue working with the association for years to come.
French archaeologists Professor Jean-Michel Geneste and Professor Jean-Jacques Delannoy took part in the excavation while Professor Hugues Plisson was a key laboratory analyst of the axe fragment along with Petchey.
Plisson, a specialist in the analysis of the tell-tale marks left on stone tool edges, examined the artefact under a microscope to confirm how it was made and what it was used for - and that it was indeed a piece from an axe.
"Each of the team members is crucial to the success of this work to ensure high-quality research. The French team members are very experienced researchers; we have collaborated on other projects and we work very well together," David says.
"A key to successful and inspirational scientific work is that team members must be more than the sum of the parts: we have to get on well, to inspire each other both with scientific excellence and, just as important if not more, with ethical and personal respect also. This is the stuff of inspiration that pulls each researcher further than they would otherwise go alone."
Surprisingly, the archaeologists believe the axe must have been made from rocks of the same material at least 40 kilometres from the shelter where the fragment was found.
David says axes occupied a unique position as long-life chopping devices among the tools Aborigines used but their manufacture was labour-intensive and they were highly valued.
During the late 19th and early 20th centuries, local Aboriginal communities believed their axes carried the ancestral forces that characterised the particular quarry from which they came.
"Their trade across the landscape moved not just the tool itself but, more importantly, the symbolic and ancestral forces of their point of origin. The axe fragment, 40 kilometres from its source, is evidence of 35,500 years of the movement of tools, technologies and ideas across the northern Australian landscape."
David says the new evidence for the earliest securely dated ground-edge implement in the world indicates that Australia was an important location of technological innovation 35,000 years ago.
Although flaked stone tools dated to more than two million years ago have been found in Ethiopia, he says shaping them by grinding does not appear in human evolution until about 35,500 years ago, which coincided with the emergence of naturalistic rock imagery.
"The discovery of this fragment of a ground-edge axe, now the oldest in the world, poses questions as to how and why stone edge grinding appears to have first evolved along the western Pacific rim.
"Hunting and gathering populations in the southern hemisphere adopted the grinding of rock for the manufacture of ground-edge axes well before their counterparts in mesolithic and neolithic Europe. This discovery has archaeological implications very different to those that have prevailed in the standard explanations of the northern hemisphere."
The archaeologists argue that the onset of the world's earliest ground-edge axe technology some 35,500 years ago was "at its core embedded in symbolic dimensions that allowed people to interact meaningfully with each other and with their landscapes and their products".
They say that ground-edge axes were adopted not just because they aided survival and made certain tasks more efficient. But because in doing so, the tools took on important new social and symbolic roles that served to cement social and territorial relationships.
A report of the discovery of the axe fragment was published in the December issue of Australian Archaeology, the official journal of the Australian Archaeological Association. The Monash project is funded by the federal government's Indigenous Heritage Programme.
* Other members of the research team include Jean-Michel Geneste, Centre National de Préhistoire, Université de Bordeaux 1, Talence, France; Hugues Plisson, Université de Bordeaux 1, Talence, France; Christopher Clarkson, School of Social Science, University of Queensland; Jean-Jacques Delannoy, Centre Interdisciplinaire Scientifique de la Montagne, Université de Savoie, Le Bourget du Lac Cedex; Fiona Petchey, Radiocarbon Dating Laboratory, University of Waikato, New Zealand.
* This article was first published in The Age newspaper in Melbourne. It is reproduced with permission.
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