Late Pleistocene–Holocene (52–10 ka) microstratigraphy, fossil taphonomy and depositional environments from Tam Pà Ling cave (northeastern Laos)

Fossil evidence for some of the earliest Homo sapiens presence in mainland Southeast Asia have been recovered from Tam Pà Ling (TPL) cave, northeastern Laos. Taphonomic indicators suggest that these human fossils washed into TPL via gradual colluviation at varying times between MIS 5–3, yet no attempt has been made to situate them within the depositional environments of the cave within these periods. This has precluded a deeper appreciation of their presence there and in the surrounding landscape. In this first microstratigraphic study of TPL, we primarily use sediment micromorphology to reconstruct the depositional environments of the cave, relate these environments with the taphonomic history of the human fossils recovered from the upper 4 m of the excavated sequence, and explore how the sediments can better explain the presence of these humans in the area during MIS 3–1 (52–10 ka). Our results demonstrate changes in local ambient conditions from being temperate to arid, with ground conditions often wet during MIS 3 and becoming increasingly seasonal (wet-dry) during MIS 2–1. The changing cave conditions impacted its interior topography and influenced the way sediments (and fossils) were deposited. Preserved combustion biproducts identified in the sediments suggest two possible scenarios, one where small forest fires may have occurred during periods of regional aridity and/or another where humans visited the cave.