A multi-proxy approach to exploring Homo sapiens’ arrival, environments and adaptations in Southeast Asia

The capability of Pleistocene hominins to successfully adapt to different types of tropical forested environments has long been debated. In order to investigate environmental changes in Southeast Asia during a critical period for the turnover of hominin species, we analysed palaeoenvironmental proxies from five late Middle to Late Pleistocene faunas. Human teeth discoveries have been reported at Duoi U’Oi, Vietnam (70–60 ka) and Nam Lot, Laos (86–72 ka). However, the use of palaeoproteomics allowed us to discard the latter, and, to date, no human remains older than ~ 70 ka are documented in the area. Our findings indicate that tropical rainforests were highly sensitive to climatic changes over that period, with significant fluctuations of the canopy forests. Locally, large-bodied faunas were resilient to these fluctuations until the cooling period of the Marine Isotope Stage 4 (MIS 4; 74–59 ka) that transformed the overall biotope. Then, under strong selective pressures, populations with new phenotypic characteristics emerged while some other species disappeared. We argue that this climate-driven shift offered new foraging opportunities for hominins in a novel rainforest environment and was most likely a key factor in the settlement and dispersal of our species during MIS 4 in SE Asia

Evolution of the Hoabinnhian techno-complex of Tam Hang rock shelter in Northeastern Laos.

International audienc

Aux origines des hommes modernes: le site de Tam Hang au Nord du Laos.

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Testing the savannah corridor hypothesis during MIS2: The Boh Dambang hyena site in southern Cambodia

The Boh Dambang karstic site in southern Cambodia, Kampot province, is a mammal bone-rich deposit in a hyena site. Very few hyena sites have been recovered in the Pleistocene of Southeast Asia, thus little information is known about the foraging abilities of hyenas during that period and their decline in the region, while the other hypercarnivores (tiger, leopard, and dhole) persisted until present day. To constrain the site we applied luminescence (red TL and single-grain OSL), ESR and U/Th dating methods to the sediments and faunal teeth, respectively. The resulting age estimates suggest that the site represents an accumulation of a young deposit with faunal teeth in the range of 25–18 ka that was last exposed to sunlight between 8 and 7 ka, and an older deposit containing older teeth (∼100–80 ka) that have been eroded from the upper caves in the system and incorporated into the younger deposit. Thus, the faunal age of 25–18 ka (MIS2), provides the best estimate for the age of the hyena site during LGM (26.5–19 ka). We analysed the assemblage of isolated teeth in terms of taxonomic diversity and abundance. The role of bone accumulators, either carnivores or rodents, has been precised through a taphonomic analysis. Diet was reconstructed through measurement of δ13C values of tooth enamel. The taphonomic analysis reveals that the hyenas were the main bone accumulators at Boh Dambang. Porcupines were aslo a factor in the accumulation of remains. The results show that the spotted hyenas hunted large-sized herbivores (>600 kg), in a mixed environment dominated by grassland. These data along with evidence from other Pleistocene faunas from Southeast Asian mainland, in terms of prey preference of hyenas (“rhinoceroses versus large bovines”) also reveal marked differences in relation to habitat type. Possible causes of the decline of the spotted hyena in the Indochinese sub-region (hypercarnivory, high trophic level, comparable foraging strategies with hunters-gatherers, and climatic changes) are tentatively proposed at this point

Anatomically modern human in Southeast Asia (Laos) by 46 ka.

International audienceUncertainties surround the timing of modern human emergence and occupation in East and Southeast Asia. Although genetic and archeological data indicate a rapid migration out of Africa and into Southeast Asia by at least 60 ka, mainland Southeast Asia is notable for its absence of fossil evidence for early modern human occupation. Here we report on a modern human cranium from Tam Pa Ling, Laos, which was recovered from a secure stratigraphic context. Radiocarbon and luminescence dating of the surrounding sediments provide a minimum age of 51-46 ka, and direct U-dating of the bone indicates a maximum age of similar to 63 ka. The cranium has a derived modern human morphology in features of the frontal, occipital, maxillae, and dentition. It is also differentiated from western Eurasian archaic humans in aspects of its temporal, occipital, and dental morphology. In the context of an increasingly documented archaic-modern morphological mosaic among the earliest modern humans in western Eurasia, Tam Pa Ling establishes a definitively modern population in Southeast Asia at similar to 50 ka cal BP. As such, it provides the earliest skeletal evidence for fully modern humans in mainland Southeast Asia

Environmental conditions framing the first evidence of modern humans at Tam Pà Ling, Laos: A stable isotope record from terrestrial gastropod carbonates

Mainland Southeast Asia is a key region to interpret modern human migrations; however, due to a scarcity of terrestrial proxies, environmental conditions are not well understood. This study focuses on the Tam Pà Ling cave site in northeast Laos, which contains the oldest evidence for modern humans in Indochina, dating back to MIS 4 (70 ± 8 ka). Snail remains of Camaena massiei found throughout the stratigraphic sequence contain a valuable oxygen and carbon isotope record of past local vegetation and humidity changes. Our data indicate that before the Last Glacial Maximum (LGM), northeast Laos was characterized by a humid climate and forested environments. With the onset of the LGM, a major climatic shift occurred, inducing a sharp decrease in precipitation and a significant decline in woodland habitats in favor of the expansion to more open landscapes. Only during the Holocene did forests return in northeast Laos, resembling present conditions. The first Homo sapiens arriving in Indochina therefore encountered landscapes dominated by woodlands with a minor proportion of open habitats

Trophic ecology of a Late Pleistocene early modern human from tropical Southeast Asia inferred from zinc isotopes

Tam Pà Ling, a cave site in northeastern Laos, has yielded the earliest skeletal evidence of Homo sapiens in mainland Southeast Asia. The reliance of Pleistocene humans in rainforest settings on plant or animal resources is still largely unstudied, mainly due to poor collagen preservation in fossils from tropical environments precluding stable nitrogen isotope analysis, the classical trophic level proxy. However, isotopic ratios of zinc (Zn) in bioapatite constitute a promising proxy to infer trophic and dietary information from fossil vertebrates, even under adverse tropical taphonomic conditions. Here, we analyzed the zinc isotope composition (66Zn/64Zn expressed as δ66Zn value) in the enamel of two teeth of the Late Pleistocene (63–46 ka) H. sapiens individual (TPL1) from Tam Pà Ling, as well as 76 mammal teeth from the same site and the nearby Nam Lot cave. The human individual exhibits relatively low enamel δ66Zn values (+0.24‰) consistent with an omnivorous diet, suggesting a dietary reliance on both plant and animal matter. These findings offer direct evidence of the broad utilization of resources from tropical rainforests by one of the earliest known anatomically modern humans in Southeast Asia