Tamil Nadu operationalises new lab to study excavated biomaterials

The Ancient DNA Laboratory at the Madurai Kamaraj University (MKU) was inaugurated last week by Finance Minister P T R Palanivel Thiaga Rajan

Over 1,500 million DNA fragments have been sequenced from samples of the remains of humans, animals, rice, and plants found during the recent archaeological excavations in Tamil Nadu by scientists from the state that will help generate ancient genomics data from the unearthed biomaterials.

The excavated materials will now be processed at the new Ancient DNA Laboratory at the Madurai Kamaraj University (MKU), inaugurated last week by Finance Minister P T R Palanivel Thiaga Rajan. The lab will conduct ancient DNA analysis of human, animal, plant, environmental, and microbiome of biomaterials unearthed at the recent archaeological excavations in Tamil Nadu that have created a buzz for their potential to help foster a better understanding of migration and its linkages with global population.

The results will be compared with thousands of ancient and modern human genomes across the globe to explain ancient human migration in detail and will be corroborated with Sangam Literature wherever possible.

The project is spearheaded by Prof G Kumaresan, Head, Department of Genetics, School of Biological Sciences, MKU, in collaboration with Prof. David Reich, a veteran in the field of ancient DNA analysis, from Harvard Medical School in the US.

“Our aim is to give scientific proof to the historical findings. We have begun the work of isolating DNA from the skeletal samples. So far, we have sequenced about 1500 millions of DNA fragments from 20 samples of humans, animals, and plants with help from various institutes,” Kumaresan told DH.

“The new lab will sequence the remaining samples. We are going through the DNA fragments that have already been sequenced minutely and will publish the results soon. The Harvard team will help us in comparing the findings,” he added.

The new lab, set up at a cost of Rs 3 crore with assistance from the Tamil Nadu and Union governments, will analyse several samples of animal and human skeletons found in excavations at Konthagai (burial site of Keeladi near Madurai), Sivagalai, Kodumanal, Adichanallur, and Mayiladumparai.

However, the task could be quite challenging as more than 99 per cent of the samples are contaminated with bacteria and the presence of human DNA is very minimal. “Anyways, this was expected as these remains could be several thousand years old. We are trying to take samples from whatever is left of the human DNA and analyse them as well,” Kumaresan added.

Since the remains are contaminated, the plan is to analyse the samples twice – once at the newly-established lab and the second time by Harvard experts to ensure that the findings are right and questions are not raised over them.

An expert team from Harvard, which has a huge database of ancient DNA, is expected to travel to Madurai by February to help the scientists here analyse the samples and discuss their findings.

The DNA collected from the samples will help understand agricultural and trade practices, while the organic molecular analysis would reveal the agricultural, cultural, and social practices in Tamil Nadu during 500 BC – 2500 BC.

“We will compare the data of ancient DNA and protein generated at our lab with global data to understand migration (of people) and the linkages with global populations. Every animal bone that has come to our lab is being analysed minutely to find out their exact species,” the professor added.

The findings of the ancient DNA analyses will be very crucial as carbon dating of artefacts found in Keeladi and Sivagalai have established that they are between 2,600 and 3,200 years old. The carbon-dating of an artefact in Keeladi revealed it belonged to 600 BCE, pushing the literature-rich Sangam Era behind by three centuries than earlier thought and making it contemporaneous with the Gangetic Plains Civilization of north India.

Kumaresan also said the lab has analysed several offering pots with remains of rice and millets that were buried in urns at sites like Konthagai. “We will now compare the data generated by us from the analyses on rice and with 4,000 varieties of rice available now. The data would be made available in the global databank to be used by the researchers further,” he added.