Blast from the East: Does Southeast Asia’s ‘Adam’ trace back to Yunnan province instead of India? Study supports new theory of region’s common ancestor

International study led by Chinese scientists traces the genetic roots of native populations in Southeast Asia back to a father figure in South China about 15,000 years ago

PUBLISHED : Wednesday, 28 October, 2015, 7:00am
UPDATED : Wednesday, 28 October, 2015, 6:41pm

He was physically strong, bloodthirsty, curious about the outside world, desperate to heavily populate his homeland, very sexually driven - and Chinese, at least in terms of where he came from geographically.

According to Professor Su Bing, these are the likely characteristics - and origin - of the so-called “Adam” figure that native populations in Southeast Asia can trace their common ancestry back to.

The claim by Su, who recently led a multinational investigation into early human migration routes in the region, is unlikely to be well-received in some quarters, particularly in India.

It has long been believed that the common ancestor of Southeast Asian populations was Indian, not a figure from South China.

The countries in this region are united by their similar physiognomy and by having the Austroasiatic family of languages as a common mother tongue, in addition to cultural and other overlaps.

After the first modern human beings walked out of Africa some 60,000 years ago, they are believed to have passed through India before spreading to Southeast Asia and South China.

Supporters of the Indian origin theory argue that nearly 10 million people in eastern India still speak Munda, an important branch of the Austroasiatic linguistic family, which is used by nearly 100 million people in Southeast Asia.

“But in fact the opposite may be true,” said Su, a researcher with the Chinese Academy of Sciences’ Kunming Institute of Zoology in southern Yunnan province.

“The genetic father of Austroasiatic speakers is more likely to have had a Chinese origin,” he added.

With the aid of collaborators from Cambodia and Thailand, Su’s team collected DNA samples from a number of tribes living deep inside forests in the region.

By comparing these rare samples with genetic data collected during previous studies from people in East India and South China, Su’s team was able to reconstruct prehistoric migration routes in these regions using mathematical models.

Whoever this patriarchal figure proves to be, his ancestors may have appeared in the southern part of China, including the area now called Yunnan province, about 40,000 years ago, according to the latest study.

This would have been a warm period in the wake of a major Ice Age, and a conducive environment to trigger a population boom.

About 15,000 years ago, the patriarchal figure in question, headed west and spread his genes rapidly across Southeast Asia, the authors contend.

He was likely part of a male group of hunter-gatherers, they said.

The journey to the west continued on until their male offspring reached eastern India about 10,000 years ago, the paper claims.

But if “Adam” was Chinese, what about “Eve”?

“There is no Eve,” said Su, who spent considerable time deciphering DNA sequences of his test subjects at the State Key Laboratory of Genetic Resources and Evolution in the Yunnan capital of Kunming.

“The male migrants mingled with local women whenever they stopped. When they moved on again, they did not take the women with them, so the Austroasiatic speakers do not have one unique genetic ‘mother’ to share,” he added.

The conclusion was based on scientific calculations. Some human genomes mutate regularly from one generation to another, and they can serve as a biological clock marking the period at which different populations sharing those genes appeared.

Researchers can locate a person’s genetic origin through either their maternal or paternal lineage.

Mitochondrial DNA (mtDNA) can only be passed down from the mother, and the way in which this has mutated at various points in history has enabled scientists to trace nearly all modern human beings to an “Eve” figure in Africa about 60,000 years ago.

But the analysis of more recent mtDNA data from south Asian populations suggests that each population may in fact have their own distinct “Eve” figure from subsequent periods.

In contrast, tracing modern man’s paternal lineage is more straightforward, according to the new study.

Su and his colleagues analysed mutations in the (male) Y-chromosome of a unique gene called O2a1-M95, which is shared by native populations in Southeast Asia.

Their findings suggested that nearly all populations in this area could be traced to a male living in southern China about 15,000 years ago.

Su said the findings do not contradict the theory that we can all trace our ancestry back to Africa.

Rather, he said, after this initial wave of migration from Africa to Asia, their study showed that another one took place from 20,000 to 15,000 years ago in the opposite direction.

And when the superior male migrants arrived in Southeast Asia, they seem to have driven away local males and taken their women.

“The possibility of war cannot be ruled out,” Su said.

“This was not the only direction of their expansion. Our previous studies showed that the same people in South China had also expanded north and claimed vast territories. We guess there may have been a population boom at that time.”

This is not the first study to challenge the Indian origin theory.

In 2011, an international team led by Professor Toomas Kivisild from the University of Cambridge in England found that people in Southeast Asia were genetically “older” than those in Eastern Africa, suggesting that their ancestral roots may be found elsewhere.

Su said his team’s study has its limits and that there is room for improvement.

Forming a biological clock of past events based on the DNA of people living today is problematic as it may have yielded incorrect dates, he said.

The researchers from China and other countries were studying fragments of genetic information preserved in ancient human remains to improve the accuracy of genetic lineage analysis, he said.

They also worked with researchers from other disciplines such as archaeology and paleoanthropology to obtain a more comprehensive picture of the movement of ancient populations across continents.

“The biggest limit of genetic analysis is that it may tell you what happened, where, when and even (to) whom, but not why,” Su said.

“What ‘Adam’ looked like, and what prompted him to take the journey westward ... we can only guess at.”

Their findings were detailed in a paper called: Y-chromosome diversity suggests southern origin and Paleolithic backwave migration of Austro-Asiatic speakers from eastern Asia to the Indian subcontinent. It was published in the journal Scientific Reports last week.