It is wonderful when different disciplines arrive at the same conclusions independently. Recent work in Austronesian languages by Gray, Drummond, and Greenhill arrived at the conclusion that Austronesian originated in Taiwan c. 5,200 years ago, and experienced a rapid expansion pulse c. 4,000 years ago that resulted in the colonization of island Southeast Asia.
This colonization event left its traces in the genomes of present-day eastern Indonesians; the pre-Austronesian inhabitants of those islands were Papuan-like, or, in terms of traditional physical anthropology Australoid, whereas the expanding Austronesian mariners were Mongoloid. If the expansion happened within the time frame in question, it can be dated by dense genotype data by looking at the relative lengths of Australoid and Mongoloid segments in extant individuals.
This is exactly what a new paper has achieved. It has determined that the "Asian" admixture signal in Eastern Indonesia dates to 4,000-3,000 years ago.
This is what the linguistic analysis by Gray et al. had to say:
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The paper has some brilliant visualizations of information, one of which is reproduced on the left. Notice the cline of Papuan ancestry in Eastern Indonesia, east of the Wallace Line.
From the paper:
PNAS doi: 10.1073/pnas.1118892109
Genetic dating indicates that the Asian–Papuan admixture through Eastern Indonesia corresponds to the Austronesian expansion
Shuhua Xu et al.
Although the Austronesian expansion had a major impact on the languages of Island Southeast Asia, controversy still exists over the genetic impact of this expansion. The coexistence of both Asian and Papuan genetic ancestry in Eastern Indonesia provides a unique opportunity to address this issue. Here, we estimate recombination breakpoints in admixed genomes based on genome-wide SNP data and date the genetic admixture between populations of Asian vs. Papuan ancestry in Eastern Indonesia. Analyses of two genome-wide datasets indicate an eastward progression of the Asian admixture signal in Eastern Indonesia beginning about 4,000–3,000 y ago, which is in excellent agreement with inferences based on Austronesian languages. The average rate of spread of Asian genes in Eastern Indonesia was about 0.9 km/y. Our results indicate that the Austronesian expansion had a strong genetic as well as linguistic impact on Island Southeast Asia, and they significantly advance our understanding of the biological origins of human populations in the Asia–Pacific region.
Link
This colonization event left its traces in the genomes of present-day eastern Indonesians; the pre-Austronesian inhabitants of those islands were Papuan-like, or, in terms of traditional physical anthropology Australoid, whereas the expanding Austronesian mariners were Mongoloid. If the expansion happened within the time frame in question, it can be dated by dense genotype data by looking at the relative lengths of Australoid and Mongoloid segments in extant individuals.
This is exactly what a new paper has achieved. It has determined that the "Asian" admixture signal in Eastern Indonesia dates to 4,000-3,000 years ago.
This is what the linguistic analysis by Gray et al. had to say:
It shows an Austronesian origin in Taiwan around 5200 years ago, followed bya settlement pause (pause 1) between 5200 and 4000 years ago. After this pause, a rapid expansion pulse (pulse 1) led to thesettlement of Island Southeast Asia, New Guinea and Near Oceania in less than 1000 years.which is entirely consistent with the 4,000-3,000 year old colonization of Eastern Indonesia deduced by genetic recombination analysis.
From the paper:
These results strongly suggest that the admixture cline in East Indonesia reflects the spread of individuals of Asian ancestry coming from the west and admixing with resident groups of Papuan ancestry. Second, the time of admixture is highlyconsistent for the two different datasets, which were estimated bytwo different methods, and suggest that the admixture began about 4,000 y ago (Figs. 1E and 2E and Table 3). This time is in excellent agreement with estimates from archaeological and linguistic data for the arrival of Austronesian speakers in East Indonesia about 3,500–4,000 y ago (9, 21). For example, the oldest pottery found in East Indonesia, associated with the Austronesian culture, dates back to 3,500 y ago (22). Moreover , a Bayesian analysis of Austronesian languages dates the Austronesian expansion into Indonesia to about 4,000 y ago and also suggests a west to east spread across East Indonesia (9).This is a wonderful co-validation of the (once controversial) use of Bayesian phylogenetics in linguistics, and time depth estimation via recombination in genetics, calibrated with "hard" archaeological evidence. It will be great to see the same consensus arrived for other families as well.
PNAS doi: 10.1073/pnas.1118892109
Genetic dating indicates that the Asian–Papuan admixture through Eastern Indonesia corresponds to the Austronesian expansion
Shuhua Xu et al.
Although the Austronesian expansion had a major impact on the languages of Island Southeast Asia, controversy still exists over the genetic impact of this expansion. The coexistence of both Asian and Papuan genetic ancestry in Eastern Indonesia provides a unique opportunity to address this issue. Here, we estimate recombination breakpoints in admixed genomes based on genome-wide SNP data and date the genetic admixture between populations of Asian vs. Papuan ancestry in Eastern Indonesia. Analyses of two genome-wide datasets indicate an eastward progression of the Asian admixture signal in Eastern Indonesia beginning about 4,000–3,000 y ago, which is in excellent agreement with inferences based on Austronesian languages. The average rate of spread of Asian genes in Eastern Indonesia was about 0.9 km/y. Our results indicate that the Austronesian expansion had a strong genetic as well as linguistic impact on Island Southeast Asia, and they significantly advance our understanding of the biological origins of human populations in the Asia–Pacific region.
Link
