Reconstructing the environmental conditions experienced by early modern humans at Tam Pà Ling (northeast Laos) using higher plant wax biomarkers

The sediments of Tam Pà Ling (TPL), northeastern Laos, have yielded the earliest evidence of Homo sapiens in mainland Southeast Asia (∼86 ka; marine isotope stage (MIS) 5 b) with a number of skeletal elements having been recovered from the sequence attesting to two populations of H. sapiens present in the vicinity between 77 ± 9 ka to 39 ± 9 ka. At present there has been very limited research into the environmental conditions that these populations encountered during MIS 5–4. In this study, we present the results of an analysis of higher plant biomarkers (n-alkanes and n-alkanols) from the sediments at TPL to reconstruct the palaeovegetation of the site and the human fossils. The n-alkane δ¹³C values demonstrate that H. sapiens encountered a predominantly C₃ forest landscape in MIS 5 b-MIS 4 that prevailed until MIS 1. Observations of a fluctuation in δ¹³C values across MIS 5 b-MIS 1 (∼86–3 ka) indicates that moisture availability was non-uniform, most likely resulting in landscape changes in and around TPL. The presence of H. sapiens at TPL during the environmental conditions associated with MIS 5 b-MIS 3 highlights the adaptability of our species to environmental dynamics at this time.