Fossil tooth from a sambar antelope, from which an enamel sample was taken to perform the zinc isotope analysis. This deer species is still present in Southeast Asia and Laos. Credit: MPI f. Evolutionary Anthropology
There is evidence that our species lived in Southeast Asia's rainforests at least 70,000 years ago. However, we don't know much about their diet or ecological adaptations to these environments due to poor preservation. A team of international scientists, led by the Max Planck Institute for Evolutionary Anthropology Leipzig and Johannes Gutenberg University Mainz, has developed a new method for studying the diet of fossil humans. This involves the analysis of stable zinc isotopes extracted from tooth enamel. This method is particularly useful in determining whether prehistoric animals and humans ate mainly meat or plants.
Many traditional beliefs have held that tropical rainforests were a barrier to Homo sapiens. There is growing evidence that humans have adapted to the tropical rainforests of Southeast Asia and thrived there. Researchers also believe that other human species, such as Homo and Homo, died out because they were unable to adapt to the same environment as us. We don't know much about the ecology of fossil humans and what they ate.
Zinc isotopes can reveal the type of food that was consumed most often
Researchers analyzed the zinc stable iotope ratios of animal and human teeth at two locations in Hu Pan Province, Laos. They were Tam P Ling (nearby) and Nam Lot (nearby). Fabrice Demeter from the University of Copenhagen says that Tam P Ling's fossil record is the most important in Southeast Asia for palaeoanthropology, archeology and palaeoanthropology. In Tam P Ling, however, there is no archeological evidence such as stone tools, plant remains, or cut marks on bone. This means that isotopic methods are the only way to get insight into past dietary dependence.
Particularly, nitrogen isotope analysis can be used to determine if humans have eaten animals or plants in the past. The collagen found in teeth and bones is difficult to preserve. This problem is more severe in tropical areas like Tam P Ling. Professor Thomas Ttken at Johannes Gutenberg University's Institute of Geosciences, says that new methods such as zinc isotope analyses of enamelcan now overcome these limitations. This allows us to study teeth from areas and periods we couldn't study before. "With the help of zinc stable isotopes ratios, Tam P Ling can be studied and we can learn about the food that our earliest ancestors ate in this area.
Since its excavation began in 2009, Tam P Ling has produced many early modern fossils of human beings. Credit: Fabrice demeter
Southeast Asia: Diet of fossil human beings
This fossil human was found in the Late Pleistocene. It dates back to 46,000 to 63,000 years. It also included various mammals from both locations, such as water buffaloes and rhinos, wild boars. deer, bears. orangutans, macaques and leopards. These animals have different eating habits, which makes them a great background for determining what humans ate at that time. Researchers can learn more about prehistoric humans' diet by studying the diversity of animal remains at particular sites.
It strongly suggests that the diet of the fossil Homo Sapiens of Tam P Ling contained both animals and plants. This omnivorous diet differs from the most common nitrogen isotope data for humans in other parts of the world during that period. In these regions, a meat-rich diet almost always is evident. "Another type of analysis was done in this studystable carbon Isotopes analysisindicates the food consumed came exclusively from forested environments," said lise Dufour (researcher at the National Natural History Museum of Paris). These results provide direct evidence of subsistence strategies used by Late Pleistocene human beings in tropical rainforests.
Nicolas Bourgon, a researcher, prepares an analysis of a sample with an MC-ICP–MS. This instrument is used in geochemistry for measuring isotopic ratios. Credit: MPI f. Evolutionary Anthropology
Research often associates our species with open environments like the steppes and savannahs. This study shows that Homo sapiens can adapt to different environments. The results of the carbon and zinc isotopes may indicate a mixture of adaptations to tropical forests seen at other Southeast Asian archeological sites. "It will be fascinating, in the future to compare our zinc-isotope results with data from other prehistoric humans species of Southeast Asia like Homo patris and Homo floresiensis and see if they could help us understand why our species went extinct," says Nicolas Bourgon, first author and researcher at the Max Planck Institute for Evolutionary Anthropology.
Continue reading Reconstructing the diets fossil vertebrates
More information: Nicolas Bourgon et al, Trophic ecology of a Late Pleistocene early modern human from tropical Southeast Asia inferred from zinc isotopes, Journal of Human Evolution, DOI: 10.1016/j.jhevol.2021.103075 Journal information: Journal of Human Evolution Nicolas Bourgon et al, Trophic ecology of a Late Pleistocene early modern human from tropical Southeast Asia inferred from zinc isotopes,
