There is much excitement in Australian archaeology about the recent publication of the results of exhaustive OSL (optically stimulated luminescence) dating of sediments associated with various artefacts at celebrity archaeological site Madjedbebe (formally known as Malakunanja II), located in western Arnhem Land, Northern Territory, Australia.
OSL dating of artefacts excavated at the site in 1973 and particularly 1989 had suggested that occupation dated to between 50 and 60 ka (kilo annum, meaning thousand years). Concerns were raised, however, about the stability and disturbance of sediments at the site and the artefacts associated with these dates were not described in detail.
A team led by Dr Chris Clarkson excavated a staggering twenty 1 x 1 m squares adjacent to the original excavations to a depth of 3.4 m. Their detailed analysis concluded that there was no size sorting or significant movement of artefactual material vertically through the deposit. The initial occupation occurs at a depth of 2.60 to 2.15 m and includes flaked stone, grounding stones and whole and fragmented ground axes, ground ochre and fragments of sheet mica. Most importantly, they argue that their detailed analysis of sediments focusing on OSL dating suggest a conservative date for this initial occupation of Madjedbebe of around 59.3 ka.
The very early date of human occupation at Madjedbebe has wide reaching implications for understanding not only the occupation of Australia (and Sahul generally) but also the movement of anatomically modern humans out of Africa and across south Asia and the interaction of modern humans with Neanderthals, Denisovans and Homo floresiensis. It also suggests that humans and the now extinct megafaunal species of marsupials cohabited for around 20 kyr.
Additionally, the results of the dating at Madjedbebe has all sorts of implications for our understanding of the archaeology of Pleistocene Australia. For example, why have so few sites been excavated that suggest such an early chronology for human colorization of the Sahul land mass? Does this simply reflect a lack of large scale excavations and OSL dating of suitable deposits? Is the site a relic of an ecological tethered initial colonising population that remained restricted to the region? Is it possible that humans simply did not cross over the arid zone of Australia? Alternatively, was the population so small outside of the tropical north that it left little archaeological trace?
The article is currently only available through a paywall at the Nature website here. There are good reviews of the project at the ABC here and at the Guardian website here