Black Death is still causing people health problems 700 years later

The Black Death – the terrible and contagious virus that destroyed up to half the population centuries ago – could still be having an effect on our health even 700 years after the fact.

Try to imagine what life was like in the mid-1300s, if you can.

It’s hard to envisage right?

Despite that, the pandemic at the time was the worst that could have possibly been conceived of – the Black Death.

Estimates suggest that as many as 200 million people died as a result of the disease, with those that survived – due to the lack of modern medicine – making it through either by the ‘Grace of God’ or more accurately a quirk of genetic mutation.

Now, incredibly complicated DNA analysis has discovered that the same mutations that helped people beat back the Black Death are linked to auto-immune disorders that people suffer with today.

Fascinating stuff, right?

The suspicion amongst researchers was that such a significant event in human history must have had an effect on evolution.

Those that survived must have had something that those that died didn’t, in short.

So, taking 206 teeth from skeletons, they were able to pinpoint whether their owners died before, after, or during the pandemic.

They discovered that if a person had the correct genetic mutations, they had a 40 percent chance of surviving the plague.

The gene in question is called ERAP2, and the ones who did survive then passed that gene mutation onto their children.

If you were lucky, you’d get it from both, leading to a high-functioning version.

"That's huge, it's a huge effect, it's a surprise to find something like that in the human genome," Professor Luis Barreiro, from the University of Chicago, told BBC News.

Another of the researchers, Professor Hendrik Poinar, called it ‘the strongest selection event in humans to date’.

To find out what they did, experiments were performed using Yersinia pestis, the bacterium responsible for the plague in the first place.

Professor Poinar described it as ‘like watching the Black Death unfold in a petri-dish’.

Anyway, 700 years later it seems as if the mutations – now much more common – are linked to auto-immune diseases such as Crohn’s Disease, meaning that whilst our ancestors staved off the plague with their genetics, it could be harming us today.

Professor Barreiro put it: "Those scars from the past still impact our susceptibility to disease today, in a quite remarkable way.”

We can’t expect the same to happen with Covid-19, though.

That virus primarily has killed the elderly, who aren’t going to have children anymore and therefore won’t pass on their genes again.

It’s the Black Death’s ability to kill just about anyone that makes it such an impactful selection event.

So impactful that we could still be reckoning with the consequences 700 years later.