The Skeletons of Roopkund Lake: What Biomolecular Degradation and Pathogen Screening Reveal About the Medieval Himalayan Mortuary Event
By studying biomolecular degradation and pathogen DNA, scientists are reconstructing the distinct timelines and preservation histories of the diverse human skeletal remains at Roopkund Lake.
Dr. Anil Patel for SwavedaOctober 9, 2026
At 5,029 meters above sea level in the Uttarakhand Himalayas, Roopkund Lake holds the skeletal remains of several hundred individuals. Local lore traditionally attributes these deaths to a single, sudden catastrophe. It was long assumed that the remains belonged to a single cohort of pilgrims caught in a devastating storm. However, modern archaeogenetics has thoroughly dismantled this unified narrative.
A comprehensive, decade-long genetic study led by Éadaoin Harney and Niraj Rai analyzed genome-wide data from 38 individuals. The findings revealed that the Roopkund remains do not represent a single tragic event, nor do they belong to a single homogeneous population. Instead, the lake contains at least three genetically distinct groups deposited over multiple events, separated by nearly a thousand years.
Understanding how these distinct groups ended up in the same high-altitude sinkhole requires looking beyond basic ancestral classification. By examining the varying levels of biomolecular degradation in the bones and screening for ancient pathogen DNA, researchers are actively reconstructing the precise environmental and taphonomic (post-mortem preservation) histories of these disparate mass-fatality events.
The Three Genetic Cohorts of Roopkund
The 38 skeletons sequenced in the 2019 study published in Nature Communications split into highly distinct ancestral clusters:
- Roopkund_A: This group comprises 23 individuals of South Asian ancestry. They did not belong to a single close-knit population but were genetically diverse, reflecting various groups across present-day India. Radiocarbon dating places their deaths between the 7th and 10th centuries CE.
- Roopkund_B: This group consists of 14 individuals with genetic ancestry typical of the eastern Mediterranean, closely matching modern populations from Crete and Greece. They died around 1800 CE, nearly a thousand years after the Roopkund_A cohort.
- Roopkund_C: A single individual of Southeast Asian-related ancestry, who died around the same time as the Roopkund_B cohort.
Stable isotope analysis of bone collagen supports these genetic divisions. The Roopkund_B individuals had uniform carbon isotope values ($\delta^\text$) indicating a diet reliant on terrestrial $\text_3$ plants like wheat and barley. Conversely, the Roopkund_A individuals showed highly varied isotope values, reflecting a mixed diet that included $\text_4$ crops like millet.
Biomolecular Preservation and Pathogen Screening
Because the remains have spent centuries exposed to high-altitude freeze-thaw cycles, rockslides, and human disturbance, their biomolecular integrity varies widely. Ancient DNA (aDNA) preservation depends heavily on the local microenvironment. Bones submerged in the freezing, low-oxygen depths of the lake tend to preserve biomolecules far better than those scattered along the rocky, sun-exposed shores, which are subjected to rapid UV and physical degradation.
To rule out an infectious epidemic as the cause of these mass deaths, the research team conducted systematic pathogen screening on the bone samples. Using high-throughput metagenomic sequencing, they screened the extractable DNA against databases of known ancient pathogens.
The results, detailed in Supplementary Note 3 of the study, yielded no evidence of bacterial pathogens. This suggests that neither the medieval South Asian pilgrims nor the 19th-century Mediterranean travelers died of a plague or similar epidemic.
However, geneticists urge caution when interpreting negative pathogen data. Pathogen DNA is typically present in much lower concentrations than human host DNA, particularly in cases of acute infections where the bacteria may not have colonized the dense cortical bone of the long limbs used for sampling. Additionally, advanced biomolecular degradation in the more exposed skeletons could have destroyed fragile microbial DNA while leaving trace amounts of human mitochondrial DNA intact.
Reconstructing the Mortuary Events
The absence of pathogens, combined with physical evidence, points back to physical trauma as the primary cause of death. Physical anthropological assessments have long noted unhealed compression fractures on several skulls. These injuries, characterized by rounded, "spoon-shaped" trauma, lack the radiating fractures typical of weapon blows, suggesting they were caused by heavy, blunt objects falling from above.
⚖ Scholarly debate: While many researchers accept that a sudden, severe hailstorm with exceptionally large hailstones remains the most plausible explanation for the deaths of both cohorts, the exact circumstances remain a subject of active discussion. Some physical anthropologists argue that rockslides, which frequently plague the steep slopes surrounding Roopkund, could also account for the observed cranial trauma and the highly fragmented state of the bones.
What the biomolecular data does resolve is the temporal division of these tragedies. The medieval Roopkund_A group likely represents local pilgrims. The timing of their deaths aligns with the historical origins of the Nanda Devi Raj Jat, a major Himalayan pilgrimage route that passes near the lake.
The presence of the Mediterranean Roopkund_B cohort in the early 19th century remains an unsolved historical mystery. There are no written records of European or Aegean travelers visiting this hyper-remote Himalayan altitude during that period. Isotopic data shows they did not consume marine resources, meaning they had likely been living inland for a significant period before making their way into the high mountains.
By continuing to model biomolecular degradation patterns and applying more sensitive, targeted capture techniques for ancient pathogens, future studies may clarify whether these travelers succumbed to the elements, sudden physical trauma, or localized exposure to altitude sickness. For now, Roopkund remains a striking example of how archaeogenetics can peel back the layers of a single site to reveal entirely unrelated historical events preserved in the same glacial ice.