Was a plague really devastating Neolithic farmers 5,200 years ago, as a new study suggests?

About 5,200 years ago, not only did the plague spread across six generations of a Swedish family, New ResearchThe researchers analyzed both the ancient DNA from these people's remains and the pathogens that left traces on them.

There were three different strains of plague, the latest of which may have been significantly more virulent than the previous two, but none of them possessed the genes that enable flea transmission that underpins the spread of bubonic plague. Black Death A disease that wiped out half the population in some parts of medieval Europe between 1347 and 1351.

The authors of the new study analyzed ancient DNA from 108 Scandinavian Neolithic people found in eight “megalithic” large stone graves in Sweden and one sarcophagus (a coffin-like box buried in the ground) in Denmark. Plague Yersinia pestis It has been found in about 17 percent of people whose DNA has been sequenced, but this figure probably underestimates its frequency.

Over the course of about 120 years, three waves of the plague spread through the population: the first two were small and contained, but the third wave spread more widely.

Population decline

Researchers suggest that widespread plague around 5,200 years ago may have contributed to a significant decline in the Neolithic population of Europe. Population declines of similar magnitude to those seen during the plague epidemic have been found in archaeological surveys carried out in southern Scandinavia and many parts of Europe over the past 15 years.

We know this because the number of radiocarbon-dated archaeological sites declines dramatically during this period, and the two lines of evidence corroborate each other, as analysis of fossil pollen from plants and trees preserved in swamps and lakes also suggests that forests regenerated in areas previously cleared for farmland.

But while the population decline is undoubted, the idea that the plague was the cause is highly questionable. To understand why, we need to go back a little further.

Agriculture was introduced to southern Scandinavia by the descendants of immigrants about 6,000 years ago. People from present-day TürkiyeAs these farmers spread across the continent over the past 2,500 years, they interbred to varying degrees with local hunter-gatherers already present in Europe.

The peasant population in southern Scandinavia grew rapidly, peaking about 5,600 years ago, 400 years after their arrival, at which point the population began to decline, perhaps by 60-70% over the next 300 years.

The population decline was gradual, rather than a sudden event like the Black Death — in fact, population levels were already at their lowest when the plague struck, the new study finds — but it's possible the plague played a role, as populations remained low.

Britain is an interesting comparison: here too, agriculture was introduced by settlers some 6,000 years ago, Exactly the same patternThe population will peak after 400 years, then decline gradually, reaching its lowest point after 500-600 years.

There is little evidence that continental connections introduced plague after the first few hundred years of agricultural migration. New immigrants from the East since 4,500 years ago.

These immigrants had a type of genetic ancestry known as Eurasian Steppe Proto-Europe, which first appeared in the western half of Europe about 5,000 years ago. Significantly, the oldest evidence of plague in Britain so far comes from two later Bronze Age sites, dating back about 4,000 years.

It is also worth noting that agriculture arrived rather late in the northwestern corner of Europe. Migrant farmers arrived in southeastern and central Europe around 8,500 and 7,500 years ago, respectively. Again, wherever people looked, The patterns of population growth and decline are similar.

In other words, there seems to be some general process going on here that we don't yet fully understand. Possible explanations could be that violence erupts when the population peaks, or that the climate cools and affects crop yields. Disease outbreaks seem less likely as an explanation at this point.