Charred nut shells from Pandanus trees, fragments of animal bone and the remains of stone axes were found in the remote Ivane Valley near the Kokoda Track by a team led by Prof Glenn Summerhayes of New Zealand’s University of Otago.
The artefacts have been dated at between 49,000 and 44,000 years old. In Australia, the Lake Mungo burial ground has been dated at about the same vintage.
The PNG find "is among the earliest evidence of human habitation in this part of the world, or indeed any place outside Africa, India and the Middle East," Prof Summerhayes told Australian Geographic.
He said the evidence showed that people “moved into highland valleys as soon as they got out of their canoes” and did not remain on the coast through an adaptive period.
The archaeological work revealed campsites buried by volcanic ash where people made stone tools, hunted small animals and gathered the high energy nuts of the local Pandanus trees in conditions much colder than the present day.
The sites were occupied during a relatively warm phase of the last ice age when New Guinea was joined to Australia as part of the continent of Sahul.
Starch grains from yams recovered in the valley appear to have been transported there from their natural habitat closer to the country's steamy sub-tropical coast.
Prof Summerhayes led the team of archaeologists from New Zealand, Australia and Papua New Guinea. He said the stone tools suggest the people deliberately modified the valley landscape, mostly likely to clear forest patches to promote the growth of useful plants such as Pandanus.
“Our findings paint a picture of a highly mobile society that quickly adapted to and survived in a radically different environment to the coastal regions they had recently arrived from.
“It is remarkable that this is occurring around 15,000 years before other modern humans would colonise Europe,” Prof Summerhayes said.
“All this is unprecedented evidence of careful, intentional colonisation over thousands of years, rather than people just wandering around foraging and moving on.
"These are unique footprints of humanity that challenge some current notions regarding at what stage humans can be truly said to have become ‘modern’ in their thinking and behaviour.”
Archaeologist Dr Andrew Fairbairn from the University of Queensland, who worked with Prof Summerhayes on the research, says it suggests early humans lived in small nomadic populations that moved up and down the mountains of PNG in search of food.
“We assume [they lived in] some form of egalitarian structure,” Dr Fairbairn said, “but it's very difficult to say from the archaeological remains alone. It was a very cold period in history and these people were both resourceful and capable to be able to live at this altitude."
While DNA evidence proves a common ancestral link between Australia's Aborigines and their modern Melanesian cousins, rising sea levels around 8,000 years ago separated the two groups of people, leading to significant differences.Photo: A resident of Ivane Valley, Paul Lamui, demonstrates how rocks were used to crack open Pandanus nuts - the same method used 50,000 years ago (Andrew Fairbairn)
Sources: ‘PNG find prompts human migration rethink’ by Julian Swallow, Australian Geographic; ‘Archaeologists shed new light on adaptability of modern humans’ ancestors’, University of Otago website; 'Ancient man cool with high altitude living' by Brian Williams, The Courier-Mail, 1 October 2010
Spotters: Murray Bladwell, 'Peter'