Bengali ancestry of Sri Lankan Tamils

SL Tamil y-chromosomes from the 1000genomes project have been uploaded to YTree, an internationally recognised Y-DNA phylogenetic tree.

Some new, unique subclades have been discovered as a result, which prove paternal ancestry among the SL Tamils from both North and South India.

The most interesting haplotype discovered is J-Z7255, an unique subclade that has only been found in Bengal and Sri Lanka:


The time to most recent common ancestor (TMRCA) of all three individuals has been calculated to around 1000 B.C. This would place it in Bengal's protohistoric period (ancient Vanga).

How did a Bengali Y-chromosome end up in Jaffna?

The most likely explanation is this SL Tamil had a Sinhala paternal ancestor who assimilated into the Tamil identity during the South Indian conquests of North-East Sri Lanka.

Interestingly, the myth of Bengali prince Vijaya migrating to Sri Lanka has been preserved in Sri Lankan Tamil folktales and chronicles, but in a garbled form.

Prof. Indrapala, the foremost expert on the history of SL Tamils states the following:

"The manner in which the Sinhalese legend came to assume this position in the traditional history of the Tamils may not be difficult to explain.

The Sinhalese of the Jaffna district as we have already seen, were at no time completely dislodged by the Tamils. Many of them probably became assimilated to the Tamil population in due course. The story of Vijaya would have been current among these people at the time of Tamil settlements. When the Sinhalese became assimilated into the Tamil population, a garbled version of the Vijaya legend would have still lingered in their memory.

At at time when their origins were forgotten, these people may have used the legend to explain the origin of the Tamil kingdom instead of that of the Sinhalese kingdom."

Other unique haplotypes shared by SL Tamils also suggest paternal ancestry from ancient Gujarat and Kerala:

Both these unique haplotypes trace their time to most recent common ancestor (TMRCA) to 700 B.C.  The migration of men carrying these unique haplogroups into Sri Lanka could have occurred at any time period after that.

Vedda DNA ancestry

The Veddas are the indigenous people of Sri Lanka, and are directly descended from Balangoda man and other mesolithic hunter gatherers.

However, the Veddas are not purely indigenous and have mixed extensively with West Eurasian enriched populations over the last 3000 years (both Dravidian and Indo-Aryan speakers). 

This is proven by the below chart.

The red bar correlates with indigenous south asian DNA. The dark purple and green bars correlate with West Eurasian DNA. The yellow bar correlates with East Asian DNA.

Source: Downie 2016

1000genomes - Sri Lankan Tamils in the UK (STU) data

The 1000 Genomes Project (abbreviated as 1KGP), launched in January 2008, was an international research effort to establish by far the most detailed catalogue of human genetic variation.

Scientists sequenced the genomes of at least 1000 anonymous participants from a number of different ethnic groups including over 100 Sri Lankan Tamils in the UK (STU).

Initially, over 100 Sinhalese in the UK were also have meant to have been sampled, but for reasons unknown this was cancelled.

The data from the 1000genomes project shows significant genetic variation within the Tamil samples (plotted in black on the below chart), with some individuals clearly being of Dalit background (labelled below as S.C - scheduled caste and represented as a black triangle).

Plot courtesy of geneticist Razib Khan. Annotations added. 

(As you go up the cline, the amount of indigenous South Asian hunter gatherer DNA increases. The Bangladeshis are shifted to the right of the cline due to East Asian admixture.)

This furthers highlights the need for future genetic studies on Sri Lanka to take into account caste and region, as there is much genetic variation within the same ethnic group. Taking a single average of all these divergent castes hides an underlying complexity.

Average results from 1000 genomes project. Courtesy of geneticist Razib Khan.