“Napoleon’s Retreat from Moscow”, oil on canvas by Adolph Northen, 1851
Surprisingly fatal disease-causing bacteria, recently discovered in the teeth of Napoleonic soldiers, are believed to have precipitated the collapse of the French emperor’s enormous infantry during his retreat from Russia.
Em 1812, Napoleon Bonaparte invaded Russia with one of the largest armies in history — the “Great Army“, made up of around half a million men.
But when they were forced to withdrawharsh winter conditions, hunger and Diseases decimated the invaders. Historians estimate that they died around 300,000 soldiers.
Historical accounts, early DNA studies, and remains of body lice found on soldiers support the idea that typhus and trench fever contributed to the fall of the army. However, a wider debate persists about the French withdrawal and the role of disease.
“It’s one of the greatest mysteries in history: Why did Napoleon lose?“, states Barbieri Reme, postdoctoral researcher at the Institute of Genomics at the University of Tartu, Estonia, cited by .
Ancient DNA contains a clue. Genetic material recovered from historical fossils, skeletons and mummies has revealed mysteries of our ancestors trapped in time.
In a new one, published on Friday in Current BiologyBarbieri and his colleagues suggest that two previously unsuspected pathogens hit Napoleon’s huge army: Salmonella entericaa bacterium that causes paratyphoid fever, and Borrelia recurrentisa bacteria that is transmitted by body lice and causes recurrent fever.
Both they would have been deadly for the soldiers, who suffered from hunger and intense cold.
“We expected to find pathogens that had already been reported”, says the geneticist Nicholas Rascovanco-author of the study and responsible for the Microbial Paleogenomics Unit at the Pasteur Institute, in France.
But when researchers analyzed DNA from the teeth of 13 Napoleonic soldiers, did not find the bacteria that cause typhus or trench fever, two diseases that had previously been associated with skeletons from that location.
Although the team did not detect these diseases, that does not mean they did not plague Napoleon’s army, Rascovan emphasizes. “What our study shows is that there was a whole series of diseases that were affecting these people”, he states.
In 2002, investigators excavated a site containing a mass grave of 2,000 to 3,000 people in Vilnius, Lithuania. Napoleonic artifacts lay scattered around the skeletons. These included old buttons and beltssuggesting that the remains represented soldiers from Napoleon’s army who had retreated from Russia in 1812.
Rascovan and his colleagues selected only 13 individualsto preserve as many skeletons as possible. They also chose this reduced number because they needed teeth that were in the best condition.
In the laboratory, the team forcibly opened the soldiers’ teeth. They put the scraped dental pulp into a DNA sequencing machine. Once sequenced, scientists sorted through the DNA results looking for disease-causing bacteria. They compared the DNA suspected of being pathogenic with known genomic sequences and then associated it with the two bacteria.
“Just by reading historical accounts, it was impossible to suspect of these two pathogens”, says Barbieri. But by developing this new methodology, researchers were able to identify bacteria from small fragments of DNA. “Personally, I am also very excited about the methodology”.
