Saturday, 26 January 2013

Indonesian mega-study (Tumonggor et al. 2013)

A new comprehensive survey of Y chromosome/mtDNA variation in Indonesia has just appeared online. From the paper:
The first stage of Indonesian prehistory represents the archipelago’s initial settlement as part of the African dispersal ~50 kya. The geography of the region was then markedly different from today. Sea levels were much lower, most modern islands had merged into larger landmasses, and the westernmost parts of Indonesia were physically contiguous with mainland Asia. This first stage is recorded by deep mtDNA lineages (M17a, M73, M47, N21, N22, R21, R22 and R23), which trace back to the main branching of macrohaplogroups M and N, and have a spotty distribution across both mainland and island southeast Asia today.
The second stage reflects recurrent colonization events from mainland Asia throughout the later Paleolithic. Many haplogroups (B4a, B4b, B4c, B4c1b3, B5a, B5b, B5b1, D and E) show origin dates of 10-40 kya (Supplementary Table 6) 25, 63 and are distributed across a wide range of mainland and island southeast Asian populations. 
The third stage represents Neolithic movements into and around island southeast Asia. Some of these may involve population dispersals from (and perhaps to) Taiwan, while others reflect movements between Indonesian island groups. Representative haplogroups include M7b3, E1a1a, M7c3c and Y2. Autosomal data strongly supports large demic movements of Asian populations into eastern Indonesia from around 4 kya 67.
and, finally:
The fourth stage reflects historic movements into Indonesia, largely involving trade and the associated spread of major religions from India, Arabia and China 71. Although found at relatively low frequency today, Y chromosome lineages representing these movements occur across Indonesia 20, notably in the west, such as the Hindu dominated island of Bali
It would be useful to study Indonesian haplogroups as a means of testing the hypothesis of Indian settlement in Australia, since it is difficult to see any such settlement that would not have passed through the Indonesian archipelago.

Of the lineages found in Indonesia, the deepest ancestry appears to be associated with mtDNA haplogroups P (54+/-16ky) and Q (38+/-9ky), both of which appear to have clear "Australo-Melanesian" associations. Of the B subclades that are lately of interest due to the publication of Tianyuan ancient DNA, the oldest one appears to be B4a (33+/-13ky).

One of the major puzzles in prehistory is the co-occurrence of mtDNA macro-haplogroups M and N in the eastern portion of Eurasia vs. the dominance of N in the western part thereof. The peninsulas of Arabia and India probably hold a key to this riddle, although in both cases the situation is obscured by subsequent events: in Arabia, there has probably been substantial population turnover during its "desert" phases, while in India there has been recent admixture between the aboriginal population and West Eurasian-derived inhabitants.

Journal of Human Genetics , (24 January 2013) | doi:10.1038/jhg.2012.154

The Indonesian archipelago: an ancient genetic highway linking Asia and the Pacific 

Meryanne K Tumonggor et al.

Indonesia, an island nation linking mainland Asia with the Pacific world, hosts a wide range of linguistic, ethnic and genetic diversity. Despite the complexity of this cultural environment, genetic studies in Indonesia remain surprisingly sparse. Here, we report mitochondrial DNA (mtDNA) and associated Y-chromosome diversity for the largest cohort of Indonesians examined to date—2740 individuals from 70 communities spanning 12 islands across the breadth of the Indonesian archipelago. We reconstruct 50 000 years of population movements, from mitochondrial lineages reflecting the very earliest settlers in island southeast Asia, to Neolithic population dispersals. Historic contacts from Chinese, Indians, Arabs and Europeans comprise a noticeable fraction of Y-chromosome variation, but are not reflected in the maternally inherited mtDNA. While this historic immigration favored men, patterns of genetic diversity show that women moved more widely in earlier times. However, measures of population differentiation signal that Indonesian communities are trending away from the matri- or ambilocality of early Austronesian societies toward the more common practice of patrilocal residence today. Such sex-specific dispersal patterns remain even after correcting for the different mutation rates of mtDNA and the Y chromosome. This detailed palimpsest of Indonesian genetic diversity is a direct outcome of the region’s complex history of immigration, transitory migrants and populations that have endured in situ since the region’s first settlement.


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