It was in 2006 that geneticist Jennifer Klunk sat down in the basement of the Museum of London. There she sorted 50 boxes of bones. In one of the boxes were the remains of people who died as a result of the Black Death. In another were the remains of people who survived the same period. This made the geneticist wonder: What caused some to die, while others survived the highly aggressive plague? This was the start of a large study, which was recently presented in the renowned journal Nature. Follows for several generations The plague ravaged Europe, North Africa and Asia approximately 700 years ago. And according to the new research, the well-known pandemic has helped to shape our biology. The researchers have found this out after analyzing quantities of DNA. And according to the results, this “legacy” is not necessarily something to cheer about. Genes that at the time provided protection against the Black Death are now associated with increased susceptibility to various diseases. This is a finding that suggests that pandemics can have unexpected and harmful consequences for several generations. One of the worst Even today, the Black Death is described as one of the worst and deadliest pandemics in world history. In densely populated areas, it killed close to 50 percent of the inhabitants. Worldwide, it is estimated that between 75–200 million people died as a result of the plague. The disease was caused by the bacterium Yersinia pestis, and was transmitted to humans via fleas. One could die within just one day. And it is this bacterium, and its effect on certain genes, that the researchers have studied. And there must be one gene variant in particular that stands out. It is known under the name ERAP2. Namely, ERAP2 appears to have helped people resist the deadly bacteria several centuries ago. But today, the same variant can cause trouble. It is associated with autoimmune diseases, such as the intestinal disease Chron’s. The scientist holds up a tooth from one of the victims of the plague. Via teeth, it has been possible to find and analyze DNA. Photo: Matt Clarke/McMaster University Ancient DNA samples In the new study, 500 ancient DNA samples were examined. The samples came from English and Danish mass graves. The various samples were divided into three categories: Those who died before, during and after the Black Death. The researchers did this to see how genes that control our immune response changed as a result of the pandemic. After this, they constructed a form of copy of each DNA sample. The copies were exposed to both the plague bacteria and other bacteria. This way they could find out how the genes reacted. The analyzes showed that the immune genes in the samples before and after the ravages of the plague were very different. Researchers have extracted DNA from the remains of people buried in pits after the Black Death. These are located in East Smithfield in the UK. Photo: Matt Clarke/McMaster University – New information The findings thus reveal that some genes must have been absolutely crucial for surviving the deadly infection, the researchers write. Further analysis further revealed that there was one change that stood out: the ERAP2 gene did not function in those who died of the plague. The ERAP gene is a protein that ensures that we form a better immune response against various bacteria. The protein does this by cutting up the bacteria, then “introducing” them to our immune cells. But if you had a damaged version of this gene, your chances of surviving the Black Death were poorer. According to the Danish researcher Simon Rasmussen, this study contributes completely new and important information. – Normally in research we have only looked at, and been interested in, the plague’s DNA – not in human DNA, he says to videnskap.dk. – Important with such hypotheses Ole Georg Moseng is professor of history at the University of South-Eastern Norway. He specializes in the history of medicine, and has written several books on plague and other pandemics, among other things. He says it is important that research is done on the consequences of this plague. – The lightning-fast development in genetics is something that brings things forward. That we get hypotheses like this – that the genetic material can change after dramatic events such as plague epidemics actually are. Moseng says it is important to understand one thing when it comes to the Black Death, and that is that it alone did not ensure the extermination of large parts of the world’s population. This has happened over a much longer period. – This plague does not hit Europe in one fell swoop. The population in Europe will decrease over the course of 150 years, perhaps by 50 percent. It is because of many, repeated plague epidemics. Not just the Black Death, he says to news. He also points out that there is little source material to say how many died during the Black Death. Ole Georg Moseng is a Norwegian professor and expert on the Black Death. Photo: Privat A form of evolution Fortunately, there are some forms of evidence from the Black Death. in the form of DNA. And most likely the plague bacterium put such great pressure on the inhabitants of the time that it has forced a form of evolution of the human genome. – It is probably a fairly expected discovery. But now they have managed to prove it, says the Danish researcher Simon Rasmussen. And according to the researchers behind the study, pandemics will probably also have an effect on our genes in the future. The Black Death Illustration of the Black Death from the Toggenburg Bible (1411). Photo: Illustration, the Toggenburg Bible from 1411 A plague epidemic that ravaged Asia and Europe in the middle of the 14th century. The Black Death is considered the worst pandemic in history, 75 million people are said to have died from the disease. It is estimated that 60 percent of Europe’s population perished. New research suggests that the plague bacteria came from Asia, and that the plague outbreak in Europe occurred 15 years after favorable climate conditions in Kazakhstan and northern China. The most widespread theory is that it was a bubonic plague. The Black Death was named after the color of the bodies of those infected. Source: Great Norwegian Lexicon.
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This is how the Black Death shaped our genes – affecting how we react to disease even today – news Trøndelag
