Steppe-->Brahmin? Final evidence against Harvard's claim

I received a reply from Harvard's Dr. David Reich to the mail I had sent (check previous post comments).

Hi Ashish,

 

The Z-scores are formal tests for model fit – appropriately calibrated by a block jackknife – and the tail of large Z-scores are simply reflecting the reality of model failure.

 

What the analyses are showing is that the “Indian Cline” is in fact best modeled as a two-dimensional cloud not a one-dimensional gradient: a mixture of three source populations that cannot be simplified to a mixture of two source populations as we had done in previous modeling for example in Reich et al. Nature 2019.

 

As such, what our enrichment analyses are showing is simply that the groups of traditionally priestly status tend to be enriched for the Steppe-related source population after controlling for the proportions from the other two.

           Yours, David 

I will address these points in this analysis post. This will be final evidence to disprove the confident Steppe--->Brahmin causality claim made in the study.

Scratching my head! - Pt 2 - Major statistical analysis gap in Narasimhan paper undermines steppe->Brahmin theory

In a previous post, I had critiqued Narasimhan et al 2019 for the inference that steppe ancestry is significantly related to modern Indian Brahmin groups, and hence provides evidence that this steppe ancestry is causal to the Indo Aryan languages.

Nevertheless, the fact that traditional custodians of liturgy in Sanskrit (Brahmins) tend to have more Steppe ancestry than is predicted by a simple ASI-ANI mixture model provides an an independent line of evidence—beyond the distinctive ancestry profile shared between South Asia and Bronze Eastern Europe mirroring the shared features of Indo-Iranian and Balto- Slavic languages (58)—for a Bronze Age Steppe the origin for South Asia’s Indo-European languages.

I gave 3 main reasons why this reasoning and analysis was faulty.

1. Correlation is not causation, Brahmin steppe can be enriched by way of intermarriage with steppe rich brides. It may not have anything to do with the steppe causing the formation of brahmin jAtis.

Scratching my head! - Criticism of Narsimhan VM et al 2019 - Pt 1

In this post, I will start getting my thoughts about the seminal SC Asian paper organized in written form. I have had these stored in my head for 2 years. The data in the paper is absolutely fantastic, and we get the first aDna from South Asia ie Swat valley. But there are so many conclusions and data analysis choices made by the authors that left me scratching my head, so much so that this post got delayed because I just have so much to say but don't know where to begin.

Brahmins from NW india have ~15% frequency of European mtDna - New paper

From:

Gagandeep Singh, Srinivas Yellapu, Harkirat Singh Sandhu, Indu Sharma, Varun Sharma & AJS Bhanwer (2021): Genetic Characterization of the North-West Indian Population: Analysis of Mitochondrial DNA Control Region Variation, Annals of Human Biology, DOI: 10.1080/03014460.2021.1879933

https://doi.org/10.1080/03014460.2021.1879933

The authors sampled 197 total people of NW India from the Jat Sikh, Bania, Khatri, Brahmin & SC castes. One of the main findings is below.

North-West Indian population groups had a total of 55.86% of samples characterised as belonging to South Asian ancestry haplogroups (M, U2, U4), followed by West Eurasian (40.18%, H, HV, I, J, K, N, R, R0, T, U1a, U5a, U7, U8a, W, X) and East Asian (3.96%, A, B, C, D, F, G ) (Fig. 1).

The below analysis is mine, after studying the raw data in the paper.