There were some questions about the Indian ancestry of the Thai. The dataset released by the Reich lab has some Thai. I pulled that data, and some other Southeast Asian groups, and Tamils and Tajiks. The merging only left 62,000 SNPs, but that’s probably enough to answer this question. The PCA above shows the West Eurasian shift of some groups. The Thai definitely seem pulled to the Tamils, and are similar to the Cambodians, but with a bit more Indian ancestry and less “southern” Southeast Asian.
Below the fold are admixture and TreeMix plots. Basically you see what I’m talking about but in more detail. The Indian-like ancestry in the Luzon samples is really Spanish. The Ami and Atyal are Taiwanese aborigines. You see that they have the least West Eurasian ancestry. Even southern mainland Chinese seem to have some of that, indicating long-distance gene flow. But groups like Miao, Vietnamese/Kinh, and Dusun (Austronesians from Borneo) don’t the Indian ancestry that Thai/Lao/Cambodians/Malay have.
I wonder how the other Indonesian people score in the same comparison?
Obs, I’d guess the Achenese would have the most Indian ancestry of all Indonesian groups. I’m not sure if low level Indian ancestry is uniformly present in the bigger groups like the Javanese, Sundanese, Minangkabau, etc. Like Razib stated with the Dusun, I would imagine most of the smaller tribal peoples in Borneo, Sumatra, Sulawesi don’t have any.
It’s pretty tricky to get a sense of ethnic groups averages here I think; the samples tend to be fairly obviously scattered with some variance persisting* and small differences in representative samples vs ground truth and regional structure make it hard to say about that. I think we are on firmer terms with talking about ranges, but even then we could be limited.
(Similar figure using data from Eurogenes Global 25. Far fewer samples from Cambodian, Malay and Burmese tho : https://imgur.com/a/vyuyIDN)
*perhaps because it’s recent, perhaps because of regional population structure we can’t see – even the Uyghurs have some dispersal here?
how did the indian ancestry get to thailand? via the east bengal route towards burma, then thailand explaining why they may have more indian ancestry than cambodians/laos as the flow of ancestry begins to dilute and taper off. or from South indian explaining the script/buildings?
It would surprise me hell a lot if the pattern was any different. Burma is closer to Inda than Thailand is. Likewise for Thais and Laos etc. Also under the even-gene-exchange scenario, smaller populations will experience greater influences from a larger population than the other way around. It is fairly safe to assume that India supported a far far larger population than SE Asia for much of the past 10000 years.
Can we be certain that the W. Eurasian ancestry in Luzon is all Spanish? The island was once home to Indicized culture, same as the rest of SE Asia.
Can we be certain that the W. Eurasian ancestry in Luzon is all Spanish? The island was once home to Indicized culture, same as the rest of SE Asia.
yes. it’s western european. i looked at autosomal, and poking around the Y is more R1b.
basically the extent of indicization in phillipines was really modest.
Have we ever wandered how much Tai, Mon-Khmer and Indian are Thai?
some in the case of the former. a bit in the northeast in last case. (e.g., ahom were tai)
Razib, do you think Bengalis have Thai admixture or just Austroasiatic Khasi and Tibeto Burmese?