April 04, 2013

The role of Taiwan in the Austronesian expansion

Of interest:

It is of interest that only two of the Pacific populations,
NZA and NZEP, both from New Zealand, are
impacted by mainland Chinese groups in the admixture
proportions (Table 4). The fact that the NZA population
is of Asian descent is the likely explanation for its connection.
In contrast, all the Austronesian Pacific populations
studied (as well as Madagascar), exhibit
widespread influences from Taiwanese aborigines, these
influences are even greater, in most instances, than the
impact from populations more geographically proximal
(for example Indonesia). Notably, the three Taiwanese
aboriginal groups that seem largely responsible for the
aforementioned effects (Paiwan, Puyuma and Saisiyat)
have been largely understudied.
The Ami, which not
only is the largest tribe (population wise) within Taiwan
but the most represented in the literature, only affects
the New Zealand groups and Madagascar but not Samoa
and Tonga (Table 4), indicating that it is essential to
include a complete survey of these tribal groups when
ascertaining phylogenetic relationships.


Am J Phys Anthropol Volume 150, Issue 4, pages 551–564, April 2013

Ascertaining the role of Taiwan as a source for the Austronesian expansion

Sheyla Mirabal et al.

Taiwanese aborigines have been deemed the ancestors of Austronesian speakers which are currently distributed throughout two-thirds of the globe. As such, understanding their genetic distribution and diversity as well as their relationship to mainland Asian groups is important to consolidating the numerous models that have been proposed to explain the dispersal of Austronesian speaking peoples into Oceania. To better understand the role played by the aboriginal Taiwanese in this diaspora, we have analyzed a total of 451 individuals belonging to nine of the tribes currently residing in Taiwan, namely the Ami, Atayal, Bunun, Paiwan, Puyuma, Rukai, Saisiyat, Tsou, and the Yami from Orchid Island off the coast of Taiwan across 15 autosomal short tandem repeat loci. In addition, we have compared the genetic profiles of these tribes to populations from mainland China as well as to collections at key points throughout the Austronesian domain. While our results suggest that Daic populations from Southern China are the likely forefathers of the Taiwanese aborigines, populations within Taiwan show a greater genetic impact on groups at the extremes of the current domain than populations from Indonesia, Mainland, or Southeast Asia lending support to the “Out of Taiwan” hypothesis. We have also observed that specific Taiwanese aboriginal groups (Paiwan, Puyuma, and Saisiyat), and not all tribal populations, have highly influenced genetic distributions of Austronesian populations in the pacific and Madagascar suggesting either an asymmetric migration out of Taiwan or the loss of certain genetic signatures in some of the Taiwanese tribes due to endogamy, isolation, and/or drift.

Link

5 comments:

terryt said...

"suggesting either an asymmetric migration out of Taiwan or the loss of certain genetic signatures in some of the Taiwanese tribes due to endogamy, isolation, and/or drift".

Probably both.

"our results suggest that Daic populations from Southern China are the likely forefathers of the Taiwanese aborigines"

That is new, but not unexpected, information. Linguists have long proposed a connection between Daic and Austronesian.

"populations within Taiwan show a greater genetic impact on groups at the extremes of the current domain than populations from Indonesia, Mainland, or Southeast Asia lending support to the “Out of Taiwan” hypothesis".

Again supporting the traditional view. I hope Maju reads this. However I'm sure he would be able to find some problem with the research.

"It is of interest that only two of the Pacific populations,
NZA and NZEP, both from New Zealand, are
impacted by mainland Chinese groups in the admixture
proportions (Table 4)".

I suspect the mainland Chinese admixture is not ancient. My brother's wife is Maori but has known Chinese ancestry via a commercial gardener one of her great grandmothers worked for. Many Chinese came out as goldminers but didn't bring women. Racist attitudes limited the options for those who didn't return to China.

German Dziebel said...

Of interest:

"Genetic distances among Taiwanese aborigines
(Gst50.040195) are such that inter-population variance
indices are higher than those found among Pacific populations
(Gst50.026919) which are geographically isolated
and contain major biogeographical barriers between
them in the form of vast open oceanic distances. Corroborating
these statements are the low heterozygosity
values (Table 1), severe heterozygote deficiencies (Supporting
Information Table 10), high number of loci
exhibiting positive inbreeding coefficient correlations
(Supporting Information Table 11) and the lowest intrapopulation
variance of all the groups of populations analyzed
(Hs50.743899) exhibited by the Taiwanese tribes
(Table 2). Altogether, these data suggest that while Taiwanese
tribes are genetically different from each other,
they are internally highly homogenous, likely due to continued
endogamy and genetic drift."

Contrary to the logic of out-of-Africa theorists, the Taiwanese example clearly shows that low intragroup genetic diversity doesn't mean that the population is recent. It's high intergroup genetic diversity coupled with high linguistic differentiation that's the better predictor of a source population.

Annie Mouse said...

Past studies have indicated that there were multiple waves out of Taiwan and probably reverse flow.

These differential effects could also represent variations in the source population over time. For example the Maori with their more homogeneous population could represent the an earlier cultural wave with later waves coming from a more admixed source population with the same cultural behaviours.

Ed said...

Wasn't there a paper out in 2008 or so that also showed the Dai to be the ancestors of Austronesians? I think they labeled them "Taiwan Natives" though.
http://www.ncbi.nlm.nih.gov/pubmed/18482451

terryt said...

"Genetic distances among Taiwanese aborigines (Gst50.040195) are such that inter-population variance indices are higher than those found among Pacific populations (Gst50.026919) which are geographically isolated and contain major biogeographical barriers between them in the form of vast open oceanic distances"

Taiwanese population does not have to be very ancient to be more ancient than the Pacific population. The latter is only 3000 years old at most, and much of the eastern region is even younger.

"For example the Maori with their more homogeneous population could represent the an earlier cultural wave with later waves coming from a more admixed source population with the same cultural behaviours".

The 'wave' idea is widely accepted. Much of the Melanesian look of Austronesian people beyond the northern Solomon Islands is almost certainly the result of later waves from northern Solomons and the original Bismark archipelago population. However the homogeneous nature of the Maori population is probaly the result of widespread cultural connections after the initial colonisation. However it is also widely accepted that the culture of Central Polynesia has been changed significantly by developements both within the region and from further west. So in a sense Maori do represent the earliest cultural wave that began in Taiwan and developed further during its short stay in the Bismark Archipelago.