Centre for Cellular and Molecular Biology (CCMB)
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Queen Ketevan of Georgia
HYDERABAD: Early in July when India ‘gifted’ Georgia the relics of its ancient Queen Ketevan, 400 years after she was brutally tortured and killed, it put the spotlight back on two things – the extraordinary work of Centre for Cellular and Molecular Biology (CCMB) scientists and the potential of DNA analysis.
Now, only with the help of bones and teeth – unearthed through excavations – scientists in Hyderabad are unravelling several ancient mysteries; some of them many centuries old.
The case of the queen, for instance, was deduced from the remains of her right arm that, by some quirk of fate, had travelled all the way to the St Augustinian convent in Goa. CCMB scientists, when roped in, compared the mitochondrial DNA (usually passed on to children from their parents) extracted from bone cells to conclude what may have happened hundreds of years ago.
“Bones or teeth are strong and do not mutilate like other body organs. Petrous bones (located at the base of the skull) and tooth pulp are particularly good sources of DNA. The DNA is first isolated and then analysed," explained Kumarasamy Thangaraj, director, Centre for DNA Fingerprinting and Diagnostics (CDFD). He was previously the chief scientist at CCMB.
And these analyses can throw up very interesting details. "For example, thousands of year-old bone samples can tell you how the genome has modified since then. We can find out what kind of diseases they might have had in those days; what type of food they may have eaten then and how those ancient populations relate to the present population,” Thangaraj said.
The Tale of Queen Ketevan
In 1613, the emperor of Persia, Shah Abbas I, led an army to conquer the Georgian kingdom and took Queen Ketevan as prisoner. For about a decade, the queen remained in Shiraz, Iran as a prisoner.
History says the Persian Emperor of modern-day Iran executed Queen Ketevan of Georgia when she refused to convert to Islam. In 1624 two Augustinian friars unearthed the queen's remains, and one of them brought the relic to the St. Augustine convent in Goa.
"We carried out ancient DNA analysis on the human bone remains excavated from the St. Augustine convent by sequencing and genotyping the mitochondrial DNA. The investigations of the remains revealed a unique mitochondrial DNA, which is absent in India, but present in Georgia and surrounding regions. Since our genetic analysis corroborates archaeological and literary evidence, it is likely that the excavated bone belongs to Queen Ketevan of Georgia. We found the DNA was that of a female as there were no Y chromosomes. We compared it with 30 samples from Georgia, out of which two samples matched,” said Kumarasamy Thangaraj.
Roopkund lake skeletons
The significance of DNA analysis was reinforced even in the case of the Roopkund lake skeletons – also unravelled by CCMB scientists. As many as 38 skeletons scattered around this 'mystery lake’ in the Himalayas were analysed to ascertain that they belonged to three distinct groups – Mediterranean, South Asian and Southeast Asian.
"A group of 23 individuals’ ancestry was traced to a range of variation of present-day South Asians; another 14 had an origin typical of the eastern Mediterranean. We also identified one individual with Southeast Asian-related ancestry,” said the CDFC chief sharing how the study established another detail – not all the remains belonged to the same era. “The remains of those with South Asian ancestry dated back to 800 Common Era while all other individuals were from 1800 Common Era," he added.
But most importantly, these findings helped in busting some wrong hypotheses that had been prevalent up until then. While one theory said that the skeletons were that of traders who perished due to an unexpected event, while crossing the borders, another claimed that they were of a king and his troop. “The third hypothesis was that they were pilgrims who were visiting Nandadevi and perished on the way. However, the findings proved otherwise and confirmed that the skeletons belonged to different populations,” Thangaraj said.
Currently, CCMB and CDFD are working on several forensic cases where bones that are months, or even years old, have been found in crime scenes. The excavated bones are being analysed at labs that specialise in ancient DNA studies.
Apart from these institutions, other labs in other parts of the world like Harvard Medical school too are doing similar work, say scientists.
What study on population by CCMB reveals
As part of a study on human evolution, CCMB sequenced 523 ancient humans to show that the primary source of ancestry in modern South Asians is a prehistoric genetic gradient between people related to early hunter-gatherers of Iran and Southeast Asia. After the decline of the Indus Valley civilization, its people mixed with individuals in the southeast to form one of the two main ancestral populations of South Asia, whose direct descendants live in southern India.