Establishing robust chronologies for models of modern human dispersal in Southeast Asia: implications for arrival and occupation in Sunda and Sahul

Models that reconstruct modern human dispersal across the great arc from Africa to Australia require solid chronologies from key sites in Southeast Asia. Sunda, the continental landmass that connects Asia to Southeast Asia and Australasia, contains important evidence to constrain both arrival and occupation of humans en route to Australia. This evidence, however, is rarely associated with robust chronologies due to an absence of stratigraphic consistency, low precision, reproducibility or accuracy. In this research, optimally stimulated luminescence (OSL) dating techniques were applied to three archaeological sites in Southeast Asia that encompass both arrival and occupation: Tam Pa Ling and Nam Lot in northern Laos and Tham Lod rockshelter in north-western Thailand. This application provided solid independent age estimates to confirm the integrity of the sequences. The timing of modern human arrival at Tam Pa Ling was identified as > 46 ka and arrival at Nam Lot after 50 ± 5 ka and before 46 ± 4 ka. Modern human occupation of Tham Lod was identified as occurring after 21 ± 4 ka and before 16 ± 2 ka. These robust chronologies have added evidence to understanding modern human arrival and occupation in Sunda. Furthermore these chronologies enable parallels to be drawn between the timing and archaeology of Late Pleistocene occupation in Sunda and Sahul. These similarities provide evidence to assess whether the Sunda occupants were the ancestors to the first Indigenous Australians.