Mystery of Himalayan Skeleton Lake unravelled
doi:10.1038/nindia.2019.133 Published online 30 September 2019
Gene detectives have solved the mystery surrounding the origins of hundreds of skeletons surfacing on a Himalayan lake every summer.
The Roopkund Lake, popularly known as Skeleton Lake, is situated at an altitude of more than 5000 metres in the Uttarakhand Himalayas and remains frozen for most part of the year. But when ice cover melts during summer, skeletons of several hundred humans surface on its edge. Ever since the discovery of these skeletons by a British forest guard in 1942, the cause of the death of these humans has remained a mystery.
Now, an international research team that analysed the DNA of the human remains, seems to have the first credible clues1.
“We have managed to understand the exact ancestry of the individuals who died in two separate events,” says Niraj Rai, one of the lead researchers from the Birbal Sahni Institute of Palaeosciences in Lucknow, India.
One group, Rai says, died around 1200 years ago and the other only about 200 years ago. “Genetic analyses reveal that these people came from South Asia and the Mediterranean regions,” he adds.
To trace their exact origins, the researchers, including geneticist David Reich from the US-based Harvard Medical School, measured the levels of carbon and nitrogen isotopes in the femur bone collagen of 38 individuals. Such isotopes reveal a person’s diet, and thus point to their native place.
The team found that 23 people ate specific plants, and animals thriving on millet – a dietary habit common in South Asia. Fourteen people, they say, consumed wheat, barley and rice – an eastern Mediterranean diet. Dietary habit, bolstered by the genetic analyses, suggests that the lake people were close to modern South Asians and natives of present-day Greece and Crete.
Detailed analyses further reveals that the people of South Asian origin arrived near the lake around 800CE, whereas the natives of Greece and Crete arrived around 1800CE, indicating that they did not die in a single catastrophic event.
The lake is not on any major trade route, but on a present-day pilgrimage route. The researchers say that the lake people, mostly middle-aged unrelated men and women, were probably pilgrims. Then how did these pilgrims die?
They have no signs of pathogens in their bones. “Instead, we found that most of the skeletons have traumatic features, including unhealed broken fragments attached to the skull,” says Rai. “This suggests that the primary cause of their death is probably due to a hailstorm, which frequently happens in the vicinity of the lake.”
“The study is impressive since its conclusions are based on sound technology and science,” says Ramasamy Pitchappan, formerly with the Madurai Kamraj University in Tamil Nadu, who studies human migration and evolution and is not involved in this research.
Pitchappan believes the whole study was based on secondary samples. He says the study would have had much more value if the researchers collected samples directly from the site. They might have missed out on different cultural traits and artifacts that the two disparate populations might have had, he says.
However, Rai and his teammates are tenacious. They plan to further analyse the traumatic marks on the skeletal remains to determine the exact cause of their death with more accuracy.
1. Harney, E. et al. Ancient DNA from the skeletons of Roopkund Lake reveals Mediterranean migrants in India. Nat. Commun. 10, 3670 (2019)