Ancient DNA analysis indicates that Yersinia pestis, the bacterium responsible for the plague, was present in Europe as early as the Neolithic period, potentially contributing to significant population declines. Research published in Nature suggests these early strains lacked the genetic mutations that later enabled the pathogen to be transmitted by fleas, altering how the disease likely spread among prehistoric human populations.
Evidence of Prehistoric Plague in Europe
Geneticists have identified Yersinia pestis in human remains dating back approximately 5,000 years. According to a study led by researchers at the University of Copenhagen and published in Cell, these ancient bacterial strains were found in skeletons recovered from sites across Europe and Asia.
The presence of the pathogen during the late Neolithic and early Bronze Age challenges previous assumptions that the plague was a relatively modern phenomenon. By analyzing dental pulp from these remains, scientists reconstructed the bacterial genome, confirming that the disease was circulating long before the recorded pandemics of the Middle Ages.
Why Early Strains Differed from Modern Variants
While the prehistoric Y. pestis shares a common ancestor with the bacterium that caused the Black Death, it lacked specific genetic adaptations. Research detailed in Current Biology highlights that the early strains were missing the ymt gene.
This gene is essential for the bacteria to survive within the gut of a flea. Without this mechanism, the prehistoric plague could not be transmitted through flea bites, which is the primary vector for bubonic plague. Instead, scientists hypothesize that this ancient version of the disease may have spread through direct contact or respiratory droplets, potentially manifesting as a pneumonic or septicemic infection.
Did Plague Cause a Population Collapse?
The "Neolithic Decline"—a period characterized by a notable reduction in human settlement density in parts of Europe—has long been a subject of archaeological debate. Some researchers suggest that the emergence of Y. pestis may have acted as a biological driver for this demographic shift.
However, the scientific community remains cautious. According to an analysis in Nature Communications, while the presence of the pathogen is confirmed, direct evidence linking a specific plague outbreak to a mass mortality event in the Neolithic period is still being debated. Scholars note that environmental factors, climate change, and shifts in agricultural practices also occurred during this timeframe, making it difficult to isolate the plague as the sole cause of population loss.
Key Takeaways
- Ancient Origins: Yersinia pestis has been identified in human remains dating back to 3000 BCE.
- Transmission Methods: Early strains lacked the ymt gene, meaning they were likely not transmitted by fleas.
- Demographic Impact: While the plague was present, researchers continue to investigate whether it was the primary cause of population fluctuations during the late Neolithic.
- Genetic Evolution: The pathogen evolved significantly over millennia, eventually acquiring the traits that led to the devastating pandemics of later history.
Frequently Asked Questions
Was this the same plague that caused the Black Death?
It is an ancestral form of the same bacterium, Yersinia pestis, but it lacked critical genetic mutations that made the later medieval plague highly contagious via flea vectors.
How do scientists find the plague in ancient bones?
Researchers extract DNA from the dental pulp found inside teeth. Because the interior of a tooth is protected, it often preserves ancient bacterial DNA better than other skeletal components.
Could this plague still exist today?
The specific prehistoric lineages identified in these studies are extinct. Modern Yersinia pestis has evolved into different lineages that still circulate in small animal populations today.