Scientists believe that extinct pathogens led to the decline of ancient civilizations

(ORDO NEWS) — Thousands of years ago, in the Eastern Mediterranean, several Bronze Age civilizations declined around the same time.

The ancient kingdom of Egypt and the Akkadian empire collapsed, and a wide-ranging social crisis occurred in the ancient Near East and the Aegean, manifesting itself in population decline, destruction, reduced trade, and significant cultural changes.

Previously it was believed that the culprits of the decline were climate change and changing addictions. However, scientists, having studied the discovered remains, found a new culprit.

In remains recovered from an ancient burial site on Crete, in a cave called Hagios Charalambos, a team led by archaeogenetics Gunnar Neumann of the Max Planck Institute for Evolutionary Anthropology in Germany has discovered genetic evidence of the bacteria responsible for two of the most serious diseases in history, typhoid fever and plague. .

Therefore, the widespread diseases caused by these pathogens cannot be discounted as a contributing factor to the social change so widespread between 2200 and 2000 BC, the researchers say.

“The emergence of these two virulent pathogens at the end of the early Minoan period in Crete,” they write in their paper, “highlights the need for the reintroduction of infectious diseases as an additional factor that may have contributed to the transformation of early complex societies in the Aegean and beyond.”

Yersinia pestis is the bacterium responsible for tens of millions of deaths, most of which have occurred in three devastating global pandemics. As disastrous as this disease may have been in past centuries, its impact prior to the Plague of Justinian, which began in 541 AD, was difficult to assess.

Recent technological and scientific advances, in particular the recovery and sequencing of ancient DNA from old bones, are revealing part of this lost history.

For example, we now suspect that the bacterium has been infecting humans since at least the Neolithic period.

Last year, scientists discovered that Stone Age hunter-gatherers likely died of the plague thousands of years before we had evidence that the disease had reached epidemic proportions.

However, the genomic evidence obtained so far has come from colder regions. Little is known about its impact on ancient societies in warmer climates, such as those in the Eastern Mediterranean, through DNA degradation at higher temperatures.

So Neumann and his team went to investigate the remains found in excavations in Crete, known for its remarkably cool and stable conditions.

They reconstructed DNA in the teeth of 32 people who died between 2290 and 1909 BC. Genetic data revealed the presence of a fairly large number of common oral bacteria, as expected.

Less expected was the presence of Y-plague in two people and two lines of Salmonella enterica, the bacterium that usually causes typhoid fever, in two others. This discovery suggests that both pathogens were present and possibly transmitted in Bronze Age Crete.

But there is one caveat. Each of the discovered lines is now extinct, making it difficult to determine how their infections may have affected communities.

The discovered plague probably could not have been transmitted by fleas, one of the traits that made other strains of the bacterium so contagious in human populations.

The flea vector carries a bubonic version of the plague: humans become infected when the bacterium enters the lymphatic system through a flea bite.

Therefore, the route of transmission for this ancient form of the bacterium may be different and cause a different form of plague. For example, pneumonic plague, which is transmitted through aerosols.

The researchers said the S. enterica lines also lacked key traits that contribute to severe disease in humans, so the virulence and transmission routes of both pathogens remain unknown.

However, the discovery suggests that both pathogens circulated in high-density regions of Crete.

Since diseases such as plague and typhus do not leave marks on bones, they are not often found in the archaeological record.

The team suggests that more detailed genetic screening of more remains from the Eastern Mediterranean could help reveal the extent to which these diseases affected the civilizations that lived there.


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