Day: July 9, 2022

The Toda are different

July 9, 2022 5 Comments filed under Razib Khan

A new paper on Southwest Indian genetics highlights the Toda sample from Genomes Asia. People in the comments of this weblog have asserted this small southern tribe may have the most “Indus Valley Civilization” ancestry in the subcontinent. This is perhaps an exaggeration, but, looking at the admixture plots the Toda clearly have hardly any steppe ancestry, but a lot less “ASI” ancestry than their tribal neighbors, with the balance being something like the IVC ancestry.

Genomes Asia doesn’t make it’s data public, and for ancestry purposes I don’t think they’ve done the best job.

Global 25 is good, but a minor issue

July 9, 2022 57 Comments filed under Popular, Razib Khan

ArainGang, has posted a pretty interesting map of various ancestry components in the subcontinent by population. It’s pretty good, especially for the south and west of the subcontinent. But, there is something weird going on in the northeast: a lot of these populations have “Ancestral Indian” (Andamanese) ancestry but hardly anything else East Asian. This seems wrong. In fact, the Khasi are on a cline to Bengalis. I ran a few analyses on samples with the Andamanese and I just don’t see that Global 25 is doing this right.

In the Global 25 model above the Khasi are 33% Ancient Indian, proxy for AASI, who are most closely related to the Andamanese. But you see in the analysis here the Khasi are along the India cline, but very shifted to the Han Chinese.

I ran a three-population test with a bunch of populations. You can see here that though the Andamanese are in the data set, the Khasi are best thought of as a mix of Han Chinese with an on-elite North Indian population.

pop a pop b f3 stat error Z-score
Khasi UP_Dalit Han_N -0.0012727 0.000328938 -3.8691
Khasi UP_Bihar_Kanjars Han_N -0.0010221 0.000334709 -3.0537
Khasi IP Han_N -0.00120191 0.000481175 -2.49787
Khasi Sintashta_MLBA Han_N -0.00080455 0.000392122 -2.05179

What does this mean? I don’t think it’s a big deal. If the population does not have East Asian ancestry to a great extent the plot by Araingang looks fine. But, obviously, Global 25 has some kinks that people need to consider. This is important because people often come to me with Global 25 as if it’s authoritative. It’s not. It’s just another way to reduce genetic variation in a human consumable fashion.

Brown Pundits