May 29, 2014

A twist in Austronesian origins

The Taiwanese origin of Austronesians is widely accepted. A new preprint confirms this theory, but adds a new twist to the story of Austronesian dispersals, as it seems that in their western expansion, Austronesians picked up some Austroasiatic ancestry. This means either that Austroasiatic speakers preceded them in islands where Austronesian languages are now spoken, or that the Austronesians picked up this kind of ancestry in the mainland before settling in the islands.

bioRxiv, doi: http://dx.doi.org/10.1101/005603

Reconstructing Austronesian population history in Island Southeast Asia

Mark Lipson et al.

Austronesian languages are spread across half the globe, from Easter Island to Madagascar. Evidence from linguistics and archaeology indicates that the "Austronesian expansion," which began 4-5 thousand years ago, likely had roots in Taiwan, but the ancestry of present-day Austronesian-speaking populations remains controversial. Here, focusing primarily on Island Southeast Asia, we analyze genome-wide data from 56 populations using new methods for tracing ancestral gene flow. We show that all sampled Austronesian groups harbor ancestry that is more closely related to aboriginal Taiwanese than to any present-day mainland population. Surprisingly, western Island Southeast Asian populations have also inherited ancestry from a source nested within the variation of present-day populations speaking Austro-Asiatic languages, which have historically been nearly exclusive to the mainland. Thus, either there was once a substantial Austro-Asiatic presence in Island Southeast Asia, or Austronesian speakers migrated to and through the mainland, admixing there before continuing to western Indonesia.

Link

9 comments:

terryt said...

"it seems that in their western expansion, Austronesians picked up some Austroasiatic ancestry".

Is that really surprising, or unexpected? Surely no-one believes human groups move anywhere without mixing with the locals to at least some extent. It is only in the Bible where we find such stories.

"This means either that Austroasiatic speakers preceded them in islands where Austronesian languages are now spoken"

Didn't we already know that people of some sort lived on those islands and had mixed with the later incoming Austronesian speakers?

"also inherited ancestry from a source nested within the variation of present-day populations speaking Austro-Asiatic languages, which have historically been nearly exclusive to the mainland".

It has been obvious for some time that Austro-Asiatic languages were spoken in Sumatra, for example, before the Austronesian expansion. The authors even say:

"While a major AA contribution to western speakers of AN languages has not been proposed in the genetic literature, results from previous genetic studies are in fact consistent with these
findings".

And further:

"The O-M95 Y-chromosome haplogroup, in particular, is prevalent in western Indonesia (20) and was previously linked to AA-speaking populations".

O-M95 is also common in Sulawesi. My bet is that Austro-Asiatic, and O-M95, is associated with the Hoabinhian.

However this is interesting:

"All admixed AN-speaking populations fit best as combinations of two or three ancestry components out of a set of four: one closely related to Papuans ('Melanesian'), one splitting deeply from the Papuan branch ('Negrito'), one most closely related to aboriginal Taiwanese, and one most closely related to H’tin (Fig. 1)".

Jon A said...

One thing not mentioned in the article is that parts of "island" Southeast Asia, precisely parts of western Indonesia, was previously part of the mainland ("Sundaland"). Presumably that would have been inhabited by Austro-Asiatic speakers, which could explain the "unexpected" presence of aboriginal AA-speakers on islands.

Alexandros HoMegas said...

The Austroasiatic family goes from India to Vietnam, there is negritos who speak a Austeoasiatic in Malaysia.

My own theory is that the Indus Valley Civillization spoke a related language to Austroasiatic.

MOCKBA said...

Aren't the 3 groups which show part-Austro-Asiatic ancestry in this study all live in Mainland Asia rather than on the islands? As far as I can tell, the locations are for Wa/Va in China, Plang/Blang and H'tin in Thailand?

andrew said...

The evidence for an Austro-Asiatic substrate in Western Indonesia is much stronger than the case for Austronesians picking up Austro-Asiatic genetics en route.

terryt said...

"The evidence for an Austro-Asiatic substrate in Western Indonesia is much stronger than the case for Austronesians picking up Austro-Asiatic genetics en route".

Yes.

Dobba Makale said...

Do someone here know what are the types of yDNA of the Tausug people and Sama people of the Sulu island in the Philippines? Linguist such as Kemp Pallesen asserts that Tausug people descended from Sama traders (men) and Visayan women (Butuanon tribe). I am skeptical of his assertations that Tausug people descended from Sama men and Visayan (Butuanon) women.

Paul White said...

"Aren't the 3 groups which show part-Austro-Asiatic ancestry in this study all live in Mainland Asia rather than on the islands?"

Yes, but for linguistic as well as genetic purposes China south of the Yangzi river (with Hainan and Taiwan) might as well be thought of as "Greater Southeast Asia".

Paul White said...

Agreed, Lipson does not really give enough credit to earlier work highlighting Austroasiatic components in ISEA genes. He does, though, make a very important contribution of his own to opening up the "Dark Ages" prior to the AN expansion.
He finds a most significant AA component not only in Borneo but also along a wide corridor from Java to Flores, plus the southern Philippines.
Bearing in mind Ice Age Sunda geography, this should come as no great surprise. It does reinforce the idea that, pre-Tai and pre-AN, Austroasiatics pervaded SEA at least as far as Eastern Indonesia.
The devastating subsequent sea-level rise would have obscured a trove of archaeological evidence and AFAIK the island chain itself is a difficult region for archaeology today.
It also seems to me that AN linguistics is still a fertile area for research - for example the Manggarai dialects are very atypical (both lexically and typologically).
Meanwhile let us hope for further ISEA coverage a la Lipson!