Madjedbebe: Australia's Oldest Known Human Occupation Site

Madjedbebe is a rock shelter in western Arnhem Land, in Australia’s Northern Territory, whose lowest layers of stone tools were dated in 2017 to about 65,000 years ago. If correct, this makes it the oldest known site of human occupation in Australia, and among the earliest evidence of Homo sapiens anywhere outside Africa. The date is debated, but the site has become central to the question of when people first reached the continent.

The site

Madjedbebe lies at the foot of the sandstone escarpment of western Arnhem Land, on the Country of the Mirarr people, close to the World Heritage–listed Kakadu National Park. It was long known to archaeologists as Malakunanja II. The shelter is a sloping overhang of rock with a deep sandy floor that has built up over tens of thousands of years, burying traces of human activity layer by layer.

The walls carry Aboriginal rock paintings, which are much younger than the deepest deposits. The site lies within the area of the Jabiluka uranium lease, and its protection was one of the issues raised during long disputes over mining in the region.

Early excavations

Madjedbebe was first excavated in 1973 by the archaeologists Johan Kamminga and Harry Allen, as part of surveys carried out before uranium mining in the Alligator Rivers region. In 1989 the archaeologists Rhys Jones and Mike Smith and the geochronologist Richard Roberts returned to date its sediments using thermoluminescence, a method that measures when mineral grains were last heated or exposed to light. In 1990 they reported that the earliest artefacts were about 50,000 to 60,000 years old.

This was a striking claim at a time when many researchers placed the arrival of people in Australia at around 40,000 years ago, close to the limit of radiocarbon dating. Some critics doubted the result, and the question remained open for more than two decades.

The 2012 and 2015 excavations

New excavations were carried out in 2012 and 2015 by a team led by Chris Clarkson of the University of Queensland, working under an agreement with the Gundjeihmi Aboriginal Corporation, which represents the Mirarr Traditional Owners. The Mirarr kept control over the excavation and the artefacts recovered.

The team used optically stimulated luminescence, dating thousands of individual sand grains, along with radiocarbon dating for the upper layers. They published their results in Nature in July 2017. The lowest dense band of artefacts was dated to about 65,000 years ago, with an uncertainty of several thousand years either way.

What people left behind

The deposits contain tens of thousands of stone artefacts. Among the most notable finds were:

• Ground-edge axe fragments from the oldest layers, the earliest known examples of this technology in the world.
• Grinding stones, possibly used for seeds, plants and pigments.
• Ochre, including ground pieces and lumps with facets worn by use, suggesting the making of pigment for painting or decoration.
• Reflective mica, perhaps mixed with pigments.

A 2020 study of charred plant remains from the lowest layers identified fruits, nuts, palm stems and starchy roots and tubers, showing that the earliest inhabitants used a wide range of plant foods, some of which needed processing before eating.

The debate

The 65,000-year date has been widely discussed. In 2018 the archaeologists James O’Connell, Jim Allen and colleagues argued that the oldest artefacts might have migrated downward through the sandy sediment, moved by termites, roots or trampling, so that they lie in sand older than themselves. They also pointed to genetic estimates suggesting humans left Africa too late to reach Australia by 65,000 years ago.

The excavation team replied that the artefacts form distinct layers, that refitting pieces of broken stone are found close together, and that the luminescence dates are internally consistent. Other researchers remain unconvinced either way. Part of the difficulty is that no human bones have been found in the oldest layers, so the case rests entirely on artefacts and on how securely they are tied to the dated sand grains. Further sites of similar age elsewhere in Australia or South-East Asia would help settle the question. Most agree that people were in Australia by at least 50,000 years ago; whether they arrived 15,000 years earlier still divides the field (see peopling of Australia).

Timeline

• c. 65,000 years ago: Date of the lowest dense layer of artefacts, according to the 2017 study.
• 1973: First archaeological excavation of the site, then called Malakunanja II.
• 1989: Jones, Smith and Roberts re-excavate and date the sediments.
• 1990: Thermoluminescence dates of about 50,000 to 60,000 years are published.
• 2012 and 2015: New excavations led by Chris Clarkson with the Mirarr.
• July 2017: Nature publishes dates of about 65,000 years.
• 2018: Critics argue the oldest artefacts may have moved downward.

Why it matters

Madjedbebe holds the oldest claimed evidence of people in Australia and shapes the wider debate over when Homo sapiens spread out of Africa (see Out of Africa). Whatever its final age, it records a remarkably early and inventive culture and is a model of archaeology carried out in partnership with Traditional Owners.