There are relatively few archaeology sites in Australia that have been dated between 45- to 50,000 years old by more than a single line of evidence.1 By arriving at the same dates via different methods allows greater confidence in the age of a site. Well beyond this ‘safe’ time frame, is Madjedbebe in northern Australia, claimed to be between 65,000 and 80,000 years old.2 Madjedbebe is truly an outlier.
Amongst the many difficulties in dating sites and objects are the fragmentary nature of finds, disturbed geological contexts (bioturbation) and insufficient data to arrive at statistical confidence. Controversial reports such as 65,000 years plus for Madjedbebe has led scientists to look carefully at environmental factors that may have affected the dating. In northern Australia the impact of termite activity3 on sediments in caves has come into focus. Convincing evidence has recently been put forward to demonstrate that termite activity in particular, has caused stone tools in Madjedbebe to have been pushed downward and thus become associated with much older sediments.4 This is extremely relevant because it is the sediments that are dated in ancient sites and a correlation made with stone tools. Based on this and other evidence the reported age of Madjedbebe cannot be conclusively accepted.
The use of molecular data to date key events in the recent history of anatomically modern humans (AMH) is a highly valuable addition to dating sediments. These can be used to estimate the timing of the movement of modern humans out of Africa and into Europe and Asia. For example, the genomic sequence of an AMH dated to 45,000 years old from western Siberia (Ust’Ishim) has revealed introgressed (hybridised) Neandertal genetic material.5 The size of this Neandertal genetic material can be used to conservatively constrain the timing of the ancestors of modern AMH out of Africa at 50- to 60,000 years ago.
Other DNA studies have provided almost identical estimates and for Australia, the appearance and strength of Neandertal and Denisovan genetic signals in the genomes of Australian Indigenous people confirm they were part of this initial diaspora. Molecular and archaeological evidence provides strong support that AMH reached Australia around 50,000 years ago or very slightly before.6 This also matches fossil and sedimentary evidence in southern Asia and is reflected in the most reliably dated sites across northern Australia.
In fact it is claimed that DNA and direct dating of carbon in skeletal remains (rather than relying on associated sediments) are essential for reliability and accuracy.7
As others have remarked, if there are sites older than 65,000 years in Australia, then these can only have been occupied by an earlier AMH population.8 This hypothetical population has left no DNA traces and would be in direct conflict with Indigenous connection to and knowledge of sites.