Ancient DNA is helping researchers uncover the structure of a prehistoric community in Southeast Asia.

The Iron Age of the Pang Mapha Range in northwestern Thailand characterizes the Iron Age. Between 2,300 and 1,000 years ago, people were buried in large wooden coffins on piles, mostly in caves and rock shelters. An international team of researchers from the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany, and the Prehistoric Population and Cultural Dynamics at the Pang Mafa Highlands Project in Bangkok, Thailand, analyzed the DNA of 33 individuals buried from five Lion Casket sites. . discovered fascinating new connections between people from the same and different places. Kin people appear to be a large and well-connected community in which genetic relatedness plays an important role in funerary ritual.

Thai Iron Age Wooden Coffin Culture

Limestone karst formations in the northwestern highlands of Thailand are dominated by deciduous and evergreen forests. Numerous caves and rock shelters pass through the mountains. In more than 40 such caves in Mae Hong Son province, you can find large wooden coffins placed on piles, dating from 2,300 to 1,000 years ago. During the Iron Age, these coffins, up to several meters long, were each made from a single piece of teak wood, with detailed carvings in geometric, animal or human shapes on the handles at each end.

This archaeological assemblage has been studied for over twenty years by members of the Prehistoric Population and Cultural Dynamics in the Pang Mafa Highlands project, under the direction of Professor Rasmi Shookongdei from the Department of Archeology, Faculty of Archeology, Silpakorn University.

“Our research examines the relationship between humans and their environment in seasonal tropics. One of the important aspects of the research is to investigate the social structure of these prehistoric communities and elucidate their connections with other pre-Neolithic, Neolithic and post-Neolithic groups in the region,” says archaeologist and senior author of the study, Rasmi Shukongdei. book. to work.

To understand the genetic profile of Log Coffin-associated populations and the relationship between people buried in various caves, an interdisciplinary team of researchers from Germany and Thailand analyzed the DNA of 33 ancient people from five Log Coffin sites. Genomes from ancient individuals enable the first detailed study of the structure of a prehistoric community in Southeast Asia.

“This project shows how ancient DNA can contribute to our understanding of past societies, their daily lives and interregional connections,” says first author Selina Karlhoff, a researcher in the Department of Archaeogenetics at the Max Planck Institute for Evolutionary Anthropology.

Complex genetic landscape of the post-Neolithic mainland of Southeast Asia

DNA preservation conditions in tropical regions are difficult, limiting genetic studies of ancient populations in Southeast Asia. Most studies were limited to individuals or small groups representative of a country and period and only identified broad patterns, such as the genetic admixture of farmers in the Yangtze River Valley in southern China with the local Hoabinhian gene pool associated with hunter-gatherers. Pre-Neolithic.

The current study identifies two distinct farmer-related ancestors in individuals associated with Log Coffin. One is associated with the Yangtze River Valley and the other is associated with the Yellow River Valley in China. Although previously published individuals from Myanmar, Laos, and Vietnam also had a Yellow River-related ancestor, this was not present in Bronze and Iron Age individuals from Ban Chiang in northeastern Thailand. These genetic differences reflect cultural differences between the two regions, such as burial practices and diet, and indicate different spheres of influence and connections to different early migration routes during the Neolithic period.

“Our results contribute to the emergence of a picture of the complex genetic landscape of the post-Neolithic mainland of Southeast Asia, but this study provides successful genetic results from samples from limestone caves in the northwestern highlands of Thailand. Future studies of samples from open archaeological sites in the lowlands look promising “If possible, they could provide additional information about the genetic history of mainland Southeast Asia,” says Vibhu Kuthanan, a scientist at Naresuan University in Thailand who helped design the study.

A detailed analysis of common parental markers that could reveal the demographic background of Log Coffin-related groups by gender will be provided in a future study. Further archaeological research in collaboration with local scientists, as well as new admixture modeling and dating methods, will better elucidate evolving patterns and allow direct links to archaeological finds and hypotheses.

First community-level analysis in Southeast Asian archaeology

At the local scale, the study provided the first community-level analysis of Southeast Asian archaeology. To investigate relationships between individuals, the authors used genetic regions that are the same in two individuals because they were inherited from a common ancestor. Analysis of blocks (of the same origin) called IBD blocks helps trace complex patterns of biological relationships within a site and between sites and has not been used in archaeological studies of Southeast Asia until now.

The study found close genetic relatives buried in the same cave system, such as parents and children or grandparents and grandchildren. This cluster of closely related individuals was more distantly related to all other individuals buried in the area.

Although this may suggest a burial site selection based on genetic relatedness, the more distant genetic relationships between Log Coffin sites, low levels of relatedness, and high mitochondrial and low genome-wide diversity suggest that Log Coffin-related groups were quite large and continuously connected. by various river valleys.

“This result is very important because wooden coffins were also used in other archaeological cultures in Southeast Asia. Comparing kinship patterns and genetic relationships across regions will be an exciting future collaborative project that could potentially explain cultural dynamics and population interactions in Southeast Asia and other regions,” he says. Rasmi Shukondei.