Discovery of Ancient Plague DNA in Siberian Teeth
In a groundbreaking study published in the journal Nature, researchers have identified the oldest known evidence of the plague, dating back approximately 5,500 years. This discovery pushes the timeline of the disease back by about 200 years, offering new insights into the prehistoric origins of one of history's deadliest pathogens. The team, led by evolutionary geneticist Eske Willerslev from the University of Copenhagen, analyzed teeth from 18 ancient hunter-gatherers buried in four cemeteries near Siberia's Lake Baikal. By extracting and sequencing DNA from dental pulp, they found remnants of Yersinia pestis, the bacterium responsible for the plague.
Implications for Understanding Plague Evolution
The findings reveal that the prehistoric plague developed in stages and infected several small family groups. Carbon dating of the bones indicates two distinct outbreaks, with the earliest cases occurring around 5,500 years ago. This predates previous evidence by two centuries and suggests that the plague was present in human populations much earlier than previously thought. The study highlights how the disease evolved from a less virulent form into the highly contagious strain that later caused the Black Death in 14th-century Europe, which wiped out a significant portion of the population.
Transmission and Impact on Ancient Communities
The research team, including co-author Ruairidh Macleod from the University of Oxford, found that the plague likely spread from marmots—large native rodents—to humans when people consumed raw organs or handled infected hides during butchery. Additionally, the disease could transmit between individuals through coughing and sneezing, indicating that respiratory transmission was already possible in prehistoric times. Many of the victims were young children aged 8 to 11, possibly due to their weaker immune systems. Notably, three young girls were buried side by side, two of whom were likely cousins, and an aunt and nephew were found together, though her niece was in a separate shared grave. This burial arrangement suggests that communities cared for their dead and maintained social bonds even in the face of devastating outbreaks.
Broader Significance for Human History
Understanding the history of the plague is crucial for comprehending human history, according to Willerslev. The disease has afflicted humans for millennia and continues to exist today, though it is now treatable with antibiotics. This ancient DNA evidence provides a window into how pathogens co-evolved with human societies and how early populations responded to infectious diseases. The study underscores the importance of interdisciplinary research, combining archaeology, genetics, and anthropology to reconstruct past events. As Macleod noted, the human element of the scientific work—knowing that people buried their dead with care—adds a poignant dimension to the findings.
Future Research Directions
This discovery opens new avenues for investigating the spread of ancient diseases and their impact on human migration and settlement patterns. By examining more ancient remains, scientists hope to trace the plague's journey across continents and understand how it adapted to different environments. The research also highlights the potential for ancient DNA to reveal hidden aspects of our past, from the evolution of pathogens to the social structures of prehistoric communities. As technology advances, further studies may uncover even older evidence of the plague, potentially rewriting the timeline of human-pathogen interactions once again.
This article is based on reporting by Phys.org. Read the original article.
Originally published on phys.org
