The skeletons of Roopkund lake in Uttarakhand, which has been a mystery for years, contain bones from an enigmatic group of eastern Mediterranean people that travelled to the Indian Himalayan site around 220 years ago, a study has revealed.

The research reveals that the site has an even more complex history than imagined.

Why is it called the mystery lake?

Situated at over 5,000 metres above sea level in the Indian Himalayas, Roopkund lake has long puzzled researchers due to the presence of skeletal remains from several hundred ancient humans, scattered in and around the lake’s shores, earning it the nickname Skeleton Lake or Mystery Lake.

Roopkund has long been subject to speculation about who these individuals were, what brought them there and how they died.

What did the study find?

The study, published in the journal Nature Communications, found that the skeletons of Roopkund lake belong to genetically highly distinct groups that died in multiple periods in at least two episodes separated by one thousand years.

Ancient DNA obtained from the skeletons of Roopkund lake - representing the first ancient DNA ever reported from India - reveals that they derive from at least three distinct genetic groups.

“We first became aware of the presence of multiple distinct groups at Roopkund after sequencing the mitochondrial DNA of 72 skeletons,” said Kumarasamy Thangaraj from the Centre for Cellular and Molecular Biology (CCMB) in Hyderabad, who started the project more than a decade ago.

Three distinct groups

Whole genome sequencing of 38 individuals revealed that there were at least three distinct groups among the Roopkund skeletons.

The first group is composed of 23 individuals with ancestries that are related to people from present-day India, who do not appear to belong to a single population, but instead derived from many different groups.

Surprisingly, the second largest group is made up of 14 individuals with ancestry that is most closely related to people who live in the eastern Mediterranean, especially present-day Crete and Greece.

A third individual has ancestry that is more typical of that found in Southeast Asia.

A time gap of 1,000 years

The findings also revealed a second surprise about the skeletons of Roopkund lake. Radiocarbon dating indicates that the skeletons were not deposited at the same time, as previously assumed.

Instead, the study finds that the two major genetic groups were actually deposited approximately 1,000 years apart.

First, during the 7th-10th centuries, individuals with Indian-related ancestry died at Roopkund, possibly during several distinct events, researchers said.

It was not until sometime during around 1800 AD that the other two groups, likely composed of travellers from the eastern Mediterranean and Southeast Asia arrived at Roopkund lake, they said.