Did a major epidemic of plague trigger a prolonged collapse in Europe’s population in late neolithic times – from around 5,600 to 4,000 years ago?

In Europe, the neolithic is part of the stone age, spanning the time from the introduction of agriculture by migrant groups from Anatolia, up until the bronze age.

Scientists now know that prehistoric plague infected neolithic farmers in Europe.

What hasn’t been clear until now is whether these early strains of the plague bacterium were even deadly. New evidence shows that they were, but other factors still don’t line up to support the evidence for a late neolithic epidemic.

Plague DNA found in human remains from over 4,000 years ago is genetically quite different to the plague strains which caused the Black Death in Europe. Prehistoric plague strains lack a gene that allows the bacteria to effectively hijack fleas, turning them into bubonic plague delivery systems.

They also have ancestral forms of other genes that are known to be important in promoting virulence. Detections of prehistoric plague cases were also quite scattered across archaeological contexts, without evidence of mass mortality accompanying outbreaks – until very recently.

All this has meant that researchers have hotly debated whether these infections caused by the plague bacterium Yersinia pestis would have been a death sentence in prehistory, or something more like a stomach bug that only occasionally causes severe complications, like plague’s ancestor, Yersinia pseudotuberculosis.

Nonetheless, the detection of many cases of plague in Europe at around the same time as a major inferred population slump – the late neolithic demographic decline – has led some to implicate........

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