Did the “Black Death” affect human evolution?

On October 20, 2022, the BBC website published an article by British journalist James Gallagher entitled “The plague that broke out 700 years ago affects your health.”

The author refers to a study by professors Hendrik Poinar and Luis Barreiro published in the scientific journal Nature. It talks about an interesting discovery by scientists: a mutation in the ERAP2 gene, which was discovered during the study of the remains of those who died from the plague. According to the research, the presence of such a mutation increased the chance of people to survive during the epidemic by 40%. However, Gallagher argues that the same mutation can cause autoimmune diseases such as Crohn’s disease. Our team decided to find out whether the gene mutation really caused natural selection among humans and whether there is a connection between the development of autoimmune diseases and the consequences of the 14th century plague pandemic.

On October 19, 2022, the scientific journal Nature published the results of a study by an international team of scientists from the US, France, Canada and the UK. Experts studied the remains of people who died from the plague during and after the pandemic in London and Denmark. In total, they analyzed 516 bone samples and found 4 significant genes for further research. They did indeed reach the conclusion outlined by BBC, but noted that more research was needed to prove this hypothesis.

On October 20, 2022, Michelle Starr published “The Black Death Shaped Human Evolution and We’re Still in Its Shadow” in ScienceAlert.

There he also argues that the plague still affects our lives nowadays, thanks to the ability to develop certain autoimmune diseases. According to the author, this is empirical evidence for a link between autoimmune risk and adaptation to an infectious disease that raged centuries ago. We note that the article does not mention the other three genes mentioned in the Nature publication.

We turned to Nariman Battulin, an expert, Candidate of Biological Sciences, Associate Professor, Head of the Laboratory of Developmental Genetics of the Institute of Cytology and Genetics of the Siberian Branch of the Russian Academy of Sciences (Novosibirsk), with a request to comment on the content of the article published by BBC:

Evolution is still working here and now, it has mowed down all the unfit. At the same time, a variant of the gene that protects us from the plague can also cause autoimmune diseases. In other words, now we are not afraid of the Black Death, but we will suffer from other diseases that are more likely to occur in carriers of this mutation. It turns out that evolution protects us from one disease, but increases the risk of developing others.

the expert explains.

Assessing the accuracy of the interpretation of scientific research materials on BBC website, Prof.Battulin notes the following:

Each of us has approximately the same set of genes, but their variants can be different: the larger the population, the more genetic variants, and each of them will give one or another trait. It can be disease resistance, height, eye color, the beauty of a peacock’s tail. If a variant provides an advantage, natural selection favors it, and its frequency can increase over generations. In order to correctly describe the results of the study presented in the article, it is necessary to say: The Black Death led to the fact that the gene became more common in the population, which provides resistance to the plague, but at the same time increases the risk of developing autoimmune diseases. That is, it must be emphasized that the epidemic led to consolidation, and not to the appearance of mutations that increase immunity to diseases.

Let’s analyze another article – “The Bright Side of the Black Plague”, which was published in the American Scientist magazine for November-December 2014. The author – Pat Lee Shipman – is sure that the pandemic has left only a positive mark on human DNA. Shipman writes about the study of anthropologist Sharon DeWitt, who studied the remains of people who lived before and after the plague. The researcher concluded that after the pandemic, human life expectancy in Europe increased to 50 years. The results of this study indicate that mortality and survivorship improved in the generations following the Black Death, and that the patterns observed are not simply an artifact of temporal changes in fertility. These results highlight the power that infectious diseases have to shape population-wide patterns of health and demography over both the short- and long-term.

At the same time, scientists and the author of the article on BBC website note that the risk of developing autoimmune diseases as a negative consequence of the presence of the ERAP2 gene.

For example, on October 20, 2022, Anastasia Nikiforova published an article in Hi-Tech journal entitled “Plague survivors left a special gene for modern people: why is it dangerous in the 21st century.” There, she argues that in our time, protection against the plague does not bring positive results, and the “version” of ERAP2 only increases the risk of autoimmune diseases. These include Crohn’s disease, rheumatoid arthritis and lupus. In her text, Nikiforova refers to a study by US scientists published in the journal Clinical and Translational Gastroenterology. However, the “side effects” of the ERAP2 mutation are only Crohn’s disease and other bowel diseases, not rheumatoid arthritis and lupus.

The last post we’ll be reviewing is “How the Black Death Changed Our Immune System” in the popular science journal Science, October 19, 2022. There are doubts about the accuracy of the results of the new study. Population geneticist Ziyue Gao of the University of Pennsylvania argues that if scientists can prove the presence of “bursts” of genes in more populations, then the possibility that the new results were skewed will be eliminated.

Conclusion

As a result, we can state that publications devoted to studies of the consequences of the Black Death describe both positive and negative aspects of the ERAP2 gene mutation. After analyzing a number of journalistic materials and receiving a comment from an expert, we came to the conclusion that mutations really protect us from the plague, and their carriers will gain an advantage if humanity again encounters its pandemic. However, the question of the influence of this gene on the development of autoimmune diseases has not yet found sufficient evidence and is debatable. This point was not indicated in the original publication on BBC portal, which is an inaccuracy in the interpretation of scientific research.

AUTHORS
© Daria Ivantsova, Egor Sarantsev, Veronica Kalinina, Natalia Tikhomirova, Eva Mikheeva, Anastasia Kudriavsteva