The DNA of a Basque and a Sardinian who besieged Barcelona in 1652 uncovers an unknown epidemic | Science

The works of the La Sagrera AVE station in Barcelona uncovered more than 500 bodies a few years ago. Some lay in small holes of four or five bodies and others were crammed into mass graves with more than 70 skeletons. They were soldiers of King Felipe IV who died in 1652 during the siege of Barcelona.

This episode is known in Catalan as the Guerra of the Reapers in reference to the peasants who took up arms with their sickles against the Spanish king and allied with the French, Louis XIII. This episode inspired the national anthem of Catalonia – “Let the enemy tremble / when they see our banner: / how we make golden ears fall, / when it is convenient to cut chains” -. Now a study shows that many of those fallen on either side were likely killed by the same bacteria.

In the seventeenth century, the place where La Sagrera station is located was the town of Sant Martí de Provençals, located at the gates of the Barcelona wall. The bodies found in the graves did not show any signs of violence. Many kept their uniforms and some even wore their boots, something very rare during the shortages and hardships of a war. Next to it were vessels and even dozens of coins with the effigies of various Spanish and Gauls kings. It appeared that the undertakers were in a great hurry to dispose of the dead and whatever else they had touched, according to the team of scientists who have analyzed their DNA for the first time. Several historical references assure that there was a plague epidemic that affected both sides.

Aerial view of the La Sagrera burials.didac pamies

The works of the AVE have continued and the bones of those combatants are now in boxes stored in the Museum of History of Barcelona. Shortly before the outbreak of the coronavirus pandemic, the CSIC geneticist Carles Lalueza-Fox went to the museum to drill the teeth of two of the corpses and analyze their DNA. The results, just published, show that it was a Basque and a Sardinian. Sardinia at that time was part of the Spanish crown.

“This work helps us understand the composition of the army at that time, which is not well known,” explains Lalueza-Fox. “Just at this time the armies of Europe professionalized and internationalized in such a way that many of their troops were mercenaries,” adds the researcher. His team has analyzed the DNA of three other bodies, still unpublished. There is another Sardinian and two non-Basque inhabitants of the Iberian Peninsula, he explains. The investigator hopes to soon be able to confirm or disprove another of the historical claims: that among the troops there were also Irish soldiers of fortune. His team is awaiting the results of DNA analysis of another 20 dead that could solve the case.

But the most interesting thing that the DNA of the deceased shows is the true cause of their death. Researchers have found no traces of plague, but they have found a type of bacteria in the salmonella genus that causes paratyphoid fever. “The curious thing is that the plague bacteria is a pathogen that tends to be very well preserved in the teeth, while the bacteria found [Salmonella enterica serovar Paratyphi C] it remains much less, ”explains Lalueza-Fox. “If there had been plague in the camp we should have found it,” he argues.

In 2018, another team of geneticists unearthed mass graves in Mexico with dead indigenous people after the arrival of the Spanish conquerors. At that time a mysterious disease called cocoliztli it killed between 50% and 90% of the original inhabitants of the area. The researchers analyzed the DNA of some of those killed and found salmonella bacteria.

Lalueza-Fox’s team now shows that genetically the bacteria found in the La Sagrera soldiers are very similar to those found in the remains of American Indians. However, they are very far from other variants of salmonella found in medieval Europe prior to the conquest of America. In times when there were no antibiotics, typhoid and paratyphoid fevers caused by these bacteria could kill up to 20% of those infected, the study explains. “Until now it was thought that the causes of the epidemics in America were measles and smallpox,” says Lalueza-Fox. “What our work shows is that probably the paratyphoid fever caused by this salmonella was also in the cocktail of diseases carried by the Europeans that caused that debacle,” he says. After the conquest, the disease returned to Europe and 160 years later it probably killed the supporters of Felipe IV who were besieging Barcelona and possibly also the reapers who defended it, the researcher concludes.

A year before the death of these soldiers there was an outbreak of plague, recalls the historian of the Autonomous University of Barcelona Luis Betrán Moya. “In the chronicles of the time and after the city suffered a terrible plague contagion during the previous year of 1651 it is easy that with this generic name of plague the increase in deaths among the soldiers besieging the city was reported”, he explains . “Diseases such as typhus and typhoid fevers were very common among the soldiers of the armies until reaching the contemporary period, related to the poor conditions of clothing, food and hygiene in the soldiers. Therefore, what the DNA shows in this article has perfect credibility ”, he adds.

“It is interesting that paratyphoid fever is often found in old specimens and is very rare today,” says Johannes Krause, a geneticist at the Max Planck Institute for Evolutionary Anthropology and a member of the team that isolated the salmonella bacteria that cause it. epidemic in postcolonial Mexico, which was “one of the greatest pandemics of the 16th century.” “It seems that these gastrointestinal diseases were more common in the past due to poor hygiene,” he adds. His colleague Alexander Herbig highlights the mobility of this pathogen. “The ancestor of the bacteria from Mexico and those found now in Barcelona probably arose in Europe, possibly in Spain. The problem is that it is difficult to reconstruct the routes through which it was expanded. We have to investigate it more “

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