The Genomes Asia 100K has put their Indian paper out. It’s OK, and mostly focuses on the fact that Indians are enriched for inbreeding vis-a-vis other world populations. There are several layers to this. In some cases, as among South Indian Hindus and Muslims, there is cousin-marriage. But, in other cases, for example, Scheduled Castes and Scheduled Tribes, there seem to be extreme bottleneck effects due to delimited marriage networks. Finally, even among large population groups, such as Iyers, there seems to be some elevation of runs of homozygosity due to endogamy.
But that’s really not what I’m interested in. This preprint has a lot of Bengalis from Birbhum district in West Bengal of various castes. The UMAP (an advance over PCA in some ways) figures aren’t super informative, but you can see that their pooled sample recapitulates the Indian subcontinent. In fact, West Bengals on the whole are to the “west” of Bangladesh samples. Totally unsurprisingly.
The main reason I’m putting this post up is the UMAP plot below. It’s hard to read (they will clean it up for final publication), and I don’t know all the castes (I’m assuming “Nabasudra” is a typo). But some things that jump out
1) Bengali Brahmins are distinct.
2) Kayastha are generic West Bengalis.
3) Some of the West Bengal samples are in the Bangladesh (collected from Dhaka) distribution. These are probably descendants of Bangal migrants from the east.
4) Some groups are very distinct. That’s partly due to strong endogamy, and in the case of Santhals high East Asian ancestry (they’re Munda). Other groups are less distinct. The “Namasudra” seem to be two groups. One overlaps with the main Bengali cluster (slight bias toward Bangladeshis), while a second group is shifted toward Scheduled Castes.
I assume readers can make more heads or tails of this, as I don’t know much about caste in West Bengal (and yes, the figure is very badly labeled/colored; this is a preprint)
Addendum: Not comments about Jatts please. I will delete them.