High in the Himalayan Mountains of India there lies a shallow body of water called Roopkund Lake. However, Roopkund Lake, also known as Skelton Lake, has an eerie past, a past that is still a mystery to scientists today.
Unexplainably, Roopkund Lake is filled with hundreds upon hundreds of human bones, it's these bones that give the lake its appropriate, yet spooky, nickname.
The origin of the bones at Skeleton Lake are as good a mystery as any. Some hypothesize that a group of people were caught in a massive storm and drowned, others speculate an avalanche could be the reason, or even giant hail.
Just recently however, results from the DNA testing of 38 skeletons has blown either of those ideas completely out of the water.
"Through the use of biomolecular analyses, such as ancient DNA, stable isotope dietary reconstruction, and radiocarbon dating, we discovered that the history of Roopkund Lake is more complex than we ever anticipated," said geneticist David Reich of Harvard Medical School.
It turns out that these skeletons came from as far away as the Southeast Asia and what is now modern day Greece, as well as the island of Crete. And they did not arrive together, but instead intermittently over a period of 1,000 years. Some specimens were, however, proven to be indigenous to the area.
"We were extremely surprised by the genetics of the Roopkund skeletons," said evolutionary biologist Éadaoin Harney of Harvard University.
"The presence of individuals with ancestries typically associated with the eastern Mediterranean suggests that Roopkund Lake was not just a site of local interest, but instead drew visitors from across the globe."
Scientists used isotopes extracted from bones to track the origins of these skeletons. Isotopes are found in the soil and can vary greatly from region to region. The isotopes are absorbed by plants, and the plants then consumed by humans. These isotopes then become part of human bones or teeth and can therefore be found thousands of years later.
"Individuals belonging to the Indian-related group had highly variable diets, showing reliance on C3 and C4 derived food sources. These findings are consistent with the genetic evidence that they belonged to a variety of socioeconomic groups in South Asia," said archaeologist Ayushi Nayak of the Max Planck Institute for the Science of Human History.
The fact that the skeletons came from far away regions isn't the most bewildering of the findings from the study. It was proven through radiocarbon dating that the bones from the Indian-related specimens had arrived between the 7th and 10th centuries CE. While the Mediterranean and Southeast Asian groups didn't arrive until sometime between the 17th and 20th centuries CE.
Evidence of other regions and times could possibly be found with future tests on other skeletons, but for now, with this small amount of results, the Roopkund Lake mystery only intensifies.
"It is still not clear what brought these individuals to Roopkund Lake or how they died," said geneticist Niraj Rai of the Birbal Sahni Institute of PalaeosciencesRai.
"We hope that this study represents the first of many analyses of this mysterious site."
