The plague was already circulating in Britain thousands of years before the Black Death.
New research reveals that Yersinia pestis was widespread across Europe during the Bronze Age, with multiple strains circulating across the continent.
The earliest evidence of the plague in Britain has been discovered.
Researchers investigating Bronze Age human remains found in Somerset and Cumbria discovered the DNA of Yersinia pestis, the bacteria that causes the plague, inside three skeletons. As this DNA is very easily degraded, it’s also possible that other individuals may have been infected.
It’s not clear whether the three known victims were killed by plague or not, but this strain appears to lack virulence genes which later pandemic-causing bacteria would have.
Dr Pontus Skoglund, a co-author of the paper and the group leader of the Francis Crick Institute’s Ancient Genomics Laboratory, says, ’This research is a new piece of the puzzle in our understanding of the ancient genomic record of pathogens and humans, and how we co-evolved.’
’We understand the huge impact of many historical plague outbreaks, such as the Black Death, on human societies and health, but ancient DNA can document infectious disease much further into the past.
’Future research will do more to understand how our genomes responded to such diseases in the past, and the evolutionary arms race with the pathogens themselves, which can help us to understand the impact of diseases in the present or in the future.’
The findings of the study were published in the journal Nature Communications.
The most recognisable symtoms of Yersinia pestis are lumps known as buboes which form around swollen lymph nodes
The origins of the plague
While there are over 20 species of bacteria in the Yersina family, only three are known to cause disease in humans. Both Y. enterocolitica and Y. pseudotuberculosis are food and water-borne diseases which cause diarrhoea-like symptoms and often aren’t serious.
This isn’t the case for Y. pestis, however. It causes three diseases, bubonic, septicaemic and pneumonic plague, all of which are very serious and can cause death without treatment by antibiotics.
Genetic studies have shown that the plague bacterium evolved from Y. pseudotuberculosis and gained genes that allowed it to infect fleas and other animal hosts while boosting its defences against their immune systems.
This took place at some point in the past 20,000 years, though it’s not known to have caused its first major pandemic until around 1,500 years ago.
This was the Justinian Plague, which is believed to have begun in Central Asia before spreading into the Mediterranean and Europe. While its severity is a matter of debate, it was certainly nowhere near as deadly as the second plague in fourteenth century Europe, better known as the Black Death.
This is thought to have been the deadliest pandemic ever, and is estimated to have killed around a third of Europe’s population at the time.
Its impacts were so pronounced that it caused social, economic and environmental changes, with a study published last year suggesting pollen levels dropped substantially in some areas as so many of the workers who tended crops died.
It was followed in the nineteenth and twentieth centuries by a smaller pandemic originating in China which subsequently spread around the world as global transport improved. It is this strain of the virus, known as Y. pestis orientalis, that is the main cause of sporadic outbreaks today.