South Asian Genotype Project, Spring 2019 update

It’s been a while since I updated the South Asian Genotype Project. Well, I updated almost everyone (‘projectmembers v2’ tab is one what you want). A few people had strangely formatted text files, so I’ll go add them tomorrow. Thanks to everyone who has submitted so far!

One of the main things that I’ve been curious about is undersampled groups. I finally got an Uttar Pradesh Kayastha in the data set (well, technically my second…but the first is a friend). I also got a submission of a Bengali Brahmin with origins in the west, and another in the east (in fact, from Comilla, which is where my own family is from). And, I got the submission of another West Bengali Kayastha.

Finally, I got another Maharashtra Kayastha.

If you click the image above you see some obvious things:

  • Bengali Brahmins don’t seem to be geographically structured. The eastern and western individuals are near each other on the PCA. Additionally, they are very close to Uttar Pradesh Pradesh Brahmins. Not the main Bangladesh cluster.
  • In contrast, the West Bengal Kayastha is positioned close to the Bangladeshis, though outside of that particular cluster.

In other words, to some extent Bengal’s landscape reflects both aspects of the South Asian genetic variation: it is strongly structured by caste, and, geography also plays a role. People from western Bengal have less East Asian ancestry and more affinity with peoples to the west on the Gangetic plain. But Bengali Brahmins are genetically entirely dissimilar from other Bengalis.

The dissimilar position of Kayastha groups across South Asia is in contrast to Brahmins. Though Brahmin groups in Bengal and South India seem to have mixed with local groups (they are always somewhat shifted to the regional substrate), overall their genetic character indicates shared common ancestry. In contrast, the different Kayastha groups seem much more likely to be a case of local populations who arose to fill a particular occupational niche that emerged with polities which required a bureaucratic class.

3 thoughts on “South Asian Genotype Project, Spring 2019 update

  1. Thanks for this. I really enjoy everything you do. But one small request: In your PCA plots, can you choose colors/shapes that are more distinguishable from one another? Labels with arrows on the plot would also do it. I can’t distinguish many of the ones in this plot, and I’m not colorblind. I love these posts, and I’d like to get as much as I can out of them!

  2. Most of the Indian caste people would be in-between North Indian Brahmins and Tamils, just like Gujrati Patel, Marathi Kayastha, Bengalis etc.

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