Genetics issues in ancient India

[Steve Farmer]

Geeta Bharathan writes:

> You might be interested in a recent article:
>
> Susanta Roychoudhury et al 2000.
> Fundamental genomic unity of ethnic India is revealed by analysis of
> mitochondrial DNA
> Current Science Vol 79 No 9: 1182-1192.
>
> You can download it from:
> http://www.iisc.ernet.in/~currsci/nov102000/contents.htm
>
> I have not read the article in detail, but it seems to be well done.
> Nevertheless, I would be cautious about making generalizations based on single
> genes/genomes, including in the European study cited below. It still is one
> line of evidence, and one that still is fragmentary.

There are now about 15 recent genetic studies of possible
relevance to migration issues in ancient India. I've collected
these to write a planned review article early next year. If
anyone is interested in an overview of the papers, I've posted
the abstracts of the most important at the following website:

http://www.safarmer.com/genetics

As you'll see if you work through the abstracts, there is very
wide divergence in these studies. If you turn to the original
articles, you'll also find numerous sampling problems and
other methodological difficulties. The temporal resolution of the
studies isn't normally sufficient to shed much if any light on the
so-called Aryan migration issue. The paper by Roychoudbury et al.
may possibly contain some supporting evidence for it (see esp. p.
1188) in its finding that haplogroup U, which is often
characterized as a Caucasoid marker, "is more frequent among most
populations of northern India (Brahmins of Uttar Pradesh, Rajput,
Muslim) who probably have had more admixture with individuals of
Caucasoid background through multiple invasions of India in
historical times than populations of the eastern or southern
region...." (p. 1188). But other papers, including an earlier
paper which Roychoudhury coauthored in 1999, point to different
conclusions. The results, to put it lightly, are all over the block.

It is important to note that mtDNA studies like this may not be
as relevant to invasion/migration issues as studies of y-chromosome
polymorphisms, which (in constrast to mtDNA studies) trace male
and not female lineages. There are only a handful of y-chromosome
studies so far of India; all of them are extremely small. They
also come up with directly contradictory results. One of these,
Bhattacharyya NP, et al., Genome Res. 1999 Aug;9(8):711-9, has
Roychoudhury as a coauthor. Copies of the original paper can be
downloaded from:

http://www.genome.org/cgi/content/full/9/8/711

There is of course much interest in seeing what you can or cannot
say about migrations in historical times using data from both
mtDNA and y-chromosome polymorphism studies. Most papers, like
Kivisild et al. (see abstracts in the first link) were designed
to
deal with data in distant prehistorical periods but have been
misused in attempting to interpret the Aryan question. Some of the
existing papers are contaminated not only by methodological but
by political/ethnic biases as well. Caveat lector!

The question of what *legitimate* light mtDNA and y-chromosome
data might -- or might not -- throw on the Aryan issue will be
discussed by one of the lead members of Cavalli-Sforza's
group (an expert on y-chromosome and mtDNA issues)
at a conference at Harvard University this coming May. Unlike most
of the authors of the papers cited in the abstracts above, he
is an expert on population biology in historical as well as
pre-historical periods. It is important to recognize at this
point that few of the existing papers were designed with
historical issues like the Aryan question in mind.

Steve Farmer