Black Death Changed Our Immune Response, Caused Autoimmune Disease

Fast & Furious Gifts: Hobbs & Shaw it’s a lot of things. It’s totally ridiculous and fun, and there’s nothing wrong with that, but it’s also an exploration of what it means to change ourselves and those around us. Whether it’s the rather obvious juxtaposition of ordinary – albeit exceptionally muscular – humans versus the scientifically enhanced Idris Elba or the slightly less-nosed Snowflake virus, which can be reprogrammed to kill humanity or administer without the effort of vaccines, it’s all really about change.

One way or another, by the time the cars stop and the credits roll, the fate of mankind will have been decided. Sorry for the spoilers if you haven’t seen Hobbs & Shaw for the past three years, but Brixton Lore of Elba is defeated and the world is saved. Hooray! Score one for the good guys, we’ll need it to feel better about how nature has been kicking us in the eye for centuries. Longer.

An international team of scientists led by researchers from McMaster University and the University of Chicago say infectious diseases are one of the strongest selection pressures facing humanity, and this is especially true when outbreaks of particularly vicious diseases. Their new study, published in the journal Naturefocuses on what scientists call “the greatest mortality event in recorded history”, the Black Death pandemic that spread across the world in the 14th century.

RELATED: DNA From Ancient Grave Reveals Black Death Patient Zero

Considering that the disease wiped out large swathes of the human population, with some regions losing more than half of their population at once, it makes sense that we have undergone adaptive changes as a result of exposure to Yersinia pestis, the bacteria that causes Black Death.

To find out, the researchers collected DNA samples from 206 Europeans from two different population groups. One group was in Denmark while the other was in London, and both groups had representatives from before, during, and after the Black Death swept through the region. Of the total 206 individuals represented in the DNA data, 67 lived before the pandemic, 97 lived after its end, and the remaining 42 lived during the plague and died from the disease.

Scientists compared DNA samples over time, looking for genes that might have changed as a result of natural selection, specifically genes that might have mutated in response to the plague. They initially found hundreds of potential candidates, but were able to narrow the search by looking for genes with opposing frequencies before and after the pandemic.

The idea here is that any beneficial mutation would necessarily be rare in people who died from the plague, but their frequency would be expected to increase among survivors. Of the hundreds they initially identified, narrowing down to genes with this feature reduced the total list to 35. From there, the scientists compared the changes in the two population groups, in Denmark and London, to see what changes occurred in both places, something else we would expect if the changes were due to a common illness. This narrowed the list down to four genes, all of which appear to have been enhanced in response to the plague pandemic.

Later lab tests suggested that mutated versions of these four genes helped protect our medieval ancestors from Y. pestis and a host of other diseases. Among the adaptations were changes that allow the immune system to better detect proteins on the surface of bacteria. This facilitates identification and destruction. Another adaptation allows immune cells to talk to each other better, so that once a cell learns about the invader, it can tell everyone else. Researchers estimate that people with two good copies of this beneficial mutation were 40% more likely to survive an infection than their peers. In the midst of a deadly disease, our immune system was busy working not only to keep our ancestors alive, but also to make them better able to survive in the future. The only problem is that they didn’t factor in the cost.

These same genes that may have helped our ancestors stave off death as the world crumbled around them have also been linked to a buffet of modern autoimmune diseases. In the calculation of the moment, this makes some kind of sense. Even if these people, surrounded by their dead and dying loved ones, might have known that evolving would mean inflammatory bowel disease for their descendants, would they have cared? Could they have cared? And would we blame them if they didn’t?

In the end, it probably doesn’t matter. They did what they did. They survived. And now we are paying the price for our ancestors surviving the Black Death with creaky joints and chronic pain.

The day of the Dead

It’s a fan thing

Join SYFY Insider to access exclusive videos and interviews, breaking news, sweepstakes and more!

Free registration

Leave a Comment