Genetic research shows the complexity of the history of migration in Southeast Asia

Skull of a Hòabìnhian individual (Photo courtesy Fabio Lahr. All rights reserved)
Skull of a Hòabìnhian individual (Photo courtesy Fabio Lahr. All rights reserved)

An article published in the journal “Science” describes the results of a genetic research on the populations of Southeast Asia. A team of researchers sequenced the DNA of 26 human beings that lived up to 8,000 years ago in various parts of that area and subsequent analysis led them to conclude that today’s populations descended from at least four ancient populations. This expands a research published in May, again in “Science”, which found three migrations, and contradicts at least two of the theories that have been discussed during the last century.

The remarkable genetic diversity existing in the populations of Southeast Asia, one of the largest in the world, made it so far difficult to reconstruct the various migrations that, over the course of many thousands of years, led to today’s occupation of that area.

For over a century scientists have been discussing the issue and in particular two theories: according to one of them, hunter-gatherers belonging to the Hòabìnhian culture that populated that area since about 44,000 years ago adopted agriculture independently while according to the other theory they were replaced by rice farmers who came from today’s China.

New genetic research allowed to go beyond the possibilities of previous research, based on archaeological, historical and linguistic evidence that weren’t enough to provide a definitive answer to the question. Mark Lipson of Harvard University led the team that carried out the research published in May, based on DNA analysis from the remains of 18 individuals who lived between 4,100 and 1,700 years ago in today’s Vietnam, Thailand, Myanmar and Cambodia. Hugh McColl and Dr. Fernando Racimo from the Danish University of Copenhagen carried out an even broader research on 26 individuals who lived up to 8,000 years ago in today’s Malaysia, Thailand, Philippines, Vietnam, Indonesia, Laos and Japan.

Mark Lipson’s team discovered subsequent waves of migrations since the Bronze Age from China that arrived in Myanmar by 3,000 years ago, in Vietnam by 2,000 years ago and in Thailand over the last 1,000 years. The difference compared to migrations in Europe is that in Southeast Asia the populations mixed up with a lesser degree.

For this reason Hugh McColl and Fernando Racimo’s team could discover the traces of a fourth migration that makes the history of Southeast Asia even more complicated. Their conclusion is in fact that both hunter-gatherers belonging to the Hòabìnhian culture and the rice farmers who came from today’s China contributed to the populations of the area along with other migrations.

These results were obtained thanks to a complex work of genetic analysis. Paleogenetics, the application of genetic techniques to extinct species to be able to obtain at least fragments of DNA from very old bones, made leaps forward allowing to analyze DNA from some hundreds of thousands of years ago but the hot-humid conditions of Southeast Asia are devastating for genome conservation. The consequence is that sequencing an 8,000 year old individual’s DNA was a great success.

Bones found on the Gua Cha site in Malaysia are part of the Duckworth Collection at the University of Cambridge and were very helpful in this research. The new discoveries brought new information on ancient migrations and on the relationship that exist between distant populations such as the Hòabìnhian and the Japanese Jomon, a step forward in the reconstruction of Asian migrations.

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