Diabetes, arthritis, and multiple sclerosis trace roots back to the Black Death | Hacker News Reader

Diabetes, arthritis, and multiple sclerosis trace roots back to the Black Death

studyfinds.org

34 pointswhalesalad17 comments

“Trace their roots” seems too strong a claim to me.

https://en.wikipedia.org/wiki/Arthritis#History: Evidence of osteoarthritis and potentially inflammatory arthritis has been discovered in dinosaurs. The first known traces of human arthritis date back as far as 4500 BC

https://en.wikipedia.org/wiki/History_of_diabetes: The condition known today as diabetes (usually referring to diabetes mellitus) is thought to have been described in the Ebers Papyrus (c. 1550 BC). Ayurvedic physicians (5th/6th century BC) first noted the sweet taste of diabetic urine, and called the condition madhumeha ("honey urine")

And of course, the article (“Evolution of immune genes is associated with the Black Death”) doesn’t say it, either, just saying that it selected for a more active immune system, increasing the risk that it becomes too active.

Makes sense, too, as they wouldn’t have been able to find many genes associated with these diseases if they mutated during the bubonic plague.

Yes, I agree. I also heard arthritis came from neanderthal dna.

These diseases were of course present before in the gene pool, else the plague could not have selected for it.

The interesting part about this is that these health issues are also linked directly with chronic stress.

As one can imagine and many have experienced first-hand over the last few years, these have been stressful times. Perhaps more studies will come out regarding stress's effect on suppressing various functions of the immune system during a pandemic.

It has especially been interesting to see the mood shift as well. People are generally irritable, angry, anxious, and have regular panic attacks compared to years prior.

Which may also explain the statistics of substance abuse being at all time highs:

https://www.cdc.gov/media/releases/2020/p1218-overdose-death...

I had a weird viral infection when I was 24. At least, that's what the doctor thought -- strep, flu, etc. all came back negative. It only lasted three days, and I was up and running again. However, it hit me during a horribly stressful time in my life -- both occupational and personal.

Well about week or so after, I seemingly woke up with a rather unusual rash-like condition. Went to a doctor, they had no idea what it was, got sent to a derm, and even they were puzzled. I shit you not, they were literally on WebMD with me in the room debating amongst themselves what it could be.

Turns out it was a rather rare subtype of an autoimmune disorder that was triggered. Of course, I have absolutely no family history of the disease (that I know of). Since I was "lucky" enough to win that lottery, I was also "lucky" enough that it never went away (it ebbs and flows, but we're two peas in a pod till I die). I'm just thankful it's not worse (yet) nor some other worse condition.

I am not as 'immortal' nor resilient as I arrogantly thought. It happened to me, and it can happen to anyone too.

Oh yea, stress is the #1 thing that makes it worse.

This is wild stuff! I would be curious which traces other pandemic pathogens like smallpox and influenza have left on us.

Edit: of course, other diseases probably left their mark on our DNA. But it seems the signal is easiest to detect with diseases that occur in large, sporadic outbreaks that rip through entire populations, thus making overall survival on having protective mutations. Since it is endemic in the Old World since prehistoric times, the changes encouraged by smallpox might be hard to find now. But there are populations in the Americas and Australia who it has been introduced to much more recently...

That article is overstating the findings. Killing off 50% of the population can only double the prevalence of a given mutation.

Aka if 20million of 100 million have X, and you kill off 50 million people then at most 20 million people of 50 million people have X. Sure jumping from 20% of the population to 40% of the population is a major change but 20% is already a large percentage of the population.

Sort of. It's not black-and-white. If the gene provides a reproductive benefit then going on from there the gene prevalence only increases.

Also genes can be complex, with partial sequences providing partial benefit etc.

Genetics is rarely that simple.

Take the scenario where Gene X has a mutation that causes a chance to get a disease.

Gene Y also increases the likelihood of developing this disease, but Gene Z mitigates the effect of Gene Y.

Maybe you also have Gene A, B and C which don't directly effect the disease, but lead to less bioavailability of nutrients that prevent the disease.

Now multiply this by tens of thousands, and maybe you also need to include RNA for some diseases/disorders and it's suddenly not very simple.

None of which matters unless those mutations are common in the population. Remember they didn’t DNA test a significant percentage of the population’s remains they only found things that where already common.

As to your point, suppose you have 100 mutations that are impacted by the Black Death but none are president in more than 0.001% of the population. Does it actually change much if some of those go to 0.002%? No

A 99% die off or similar bottlenecks can make huge changes at the population level, but a single 50% die off simply isn’t that impactful.

But then, subsequent breeding will skew these results far more than the initial event. You just need a mutated Genghis Khan.

If they had some long term evolutionary advantage then without or without the Black Death they become prevalent either way.

Genghis Khan, is known for having a great number of dependents but many of those people have zero DNA that actually traces back to him. Something like 30% of everyone living 1000+ years have decedents making up a noticeable fraction of the world’s population today. However, without some evolutionary advantage any given bit of their DNA only has a ~50% chance of being passed on to their kids.

> In subsequent bubonic plague outbreaks over the next 400 years, mortality rates decreased. This could have been the result of changing cultural practices, pathogen evolution, or human genetic resistance.

Multiple rounds.

None of which where anywhere near deadly enough to change European genetics.

In theory it’s possible a 50% bottleneck to push a trait from 45% of a population to at most 90% at the extreme end. However, 45% of a population having some trait(s) without earlier evolutionary pressure is extremely unlikely. Thus, the prevalence of those traits would trace back to that earlier genetic pressure.

Genes that already provide a protective function alone but cause problems in combinations like 2 copies or with other similarly protective genes are naturally going to stay around but not become prevalent. A serious event or events creates a situation where these genes become common enough to hit the bad combinations much more often.

Naturally not everyone has type I diabetes and MS.

Sure, but again all that changed was a slight change in the frequency of this interaction not the existence of it.

It’s simply not enough change at the population level to turn extremely rare genetic disorders into common problems.

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