How the Great Depression shaped people’s DNA | Hacker News Reader

How the Great Depression shaped people’s DNA

nature.com

67 pointspseudolus27 comments

This smells of p-hacking to me. Only 2 of 6 tests showed statistical significance and it was a relatively modest effect. Not impossible that there's an actual causal link. But I'm not quite buying yet given the amount of normalization they did and size of the effect.

This seems to also validate the feelings of black Americans who themselves may not have experienced segregation but were born soon after from parents who had. And I wonder how many generations it can have effects. E.g. could there still be markers from the effects of slavery?

Absolutely, I don't know if they're identified yet but generational trauma and stress is definitely a thing and it gets passed down

When we use phrases like "generational trauma" being passed down, we end up misleading a lot of people on how genetics work. This phrase is often used in a political context, and to my knowledge there is not a good scientific foundation for it.

Information on epigenetic inheritance

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6172332/

I'm familiar with generational trauma from a psychological perspective, but wouldn't a genetical/physiological aspect of it have to be self limiting? I mean, I'm sure we all have millions of years of trauma in our genetic past.

The same could be said for trauma that is passed behaviorally, it is limited eventually. I would actually suspect they are related

The findings may validate the feelings of anyone oppressed or suffering long-term deprivation, but what does it really mean for their descendants? For example, what were the long-term effects, not just for black Americans, but for survivors of the Irish Potato Famine or the Holocaust? And if the effects were negligible for these latter two groups, what does that mean for the former?

Considering most humans in most places at most times lived in deprived circumstances, I wouldn't jump to conclusions just yet on the nature of Schmitz et al.'s findings. Remember their findings 'could be linked,' not 'are linked.'

Exposure to famine, or more generally malnutrition, is linked with diabetes and heart disease. Exposure to DDT effects epigenetic changes, resulting in predisposition to obesity. It's hard to believe that generations of oppression inflicted on black and indigenous Americans wouldn't have a lasting impact. Especially given the prevalence of obesity, heart disease and diabetes in those populations.

https://heart.bmj.com/content/84/6/595

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7428621/

https://www.thejuggernaut.com/south-asian-diabetes-incidence

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4124473/

Slavery has introduced a strong evolutionary pressure which has a measurable effect on the genetic mix present in African Americans. Sadly, the subject is barely researched (the last time I checked, the only paper tackling the subject directly had been written by a team of Chinese researchers that are now studying the genetics of Uyghurs...), for understandable reasons (no one wants to risk having their research misrepresented by racists in search of scientific justifications).

The article is missing any discussion of why this should be. You wouldn't expect epigenetic changes to simply be the direct result of, say, lack of food. Instead, it would seem like this must be a "deliberate" adaptive response, to prepare for what is likely to be a life of hardship. It might cause faster aging, but if so, one would expect that it also has some other effects that improve earlier survival and reproduction in a harsh environment.

"to prepare for what is likely to be a life of hardship"

But then we had boom times a mere 15 years later. Human society causes mass changes at short time scales. Biological mechanisms we may have facilitating adaptation to more long-term changes are likely to be counterproductive when the socioeconomic environment changes.

Maybe in the past times of hardship would tend to be either quick (a year or two) or slow (a generation of so), but as expected lifespans increase and as technology causes more intermediate length boom-bust cycles, epigenetic changes could be maladaptive over the lifetime of the individual. This is moreso true when the adaptations needed are not those of a hunter-gather (such as earlier onset puberty), but of an industrialized society (where early puberty can impact lifetime employment).

And with anything biological weird side-effects, or even mistakes can happen. Looking at the wikipedia article "Epigenetic effects of smoking" has this blurb: " CYP1A1 was found to be hypomethylated in the placentas of fetuses prenatally exposed to cigarette smoke, along with the transposable element AluYB8.[4] Methylation of transposable elements is one of the primary ways they are prevented from replicating or moving within the genome."

So you've got increased mutation rates (from the transposable elements and other effects) in infants exposed to cigarette smoke. Increasing mutation is a literal gamble for a genome to do, as only a few mutations will be beneficial.

Sometimes the situation is bad enough the body needs to gamble. But this doesn't mean the effects will be net beneficial, just that the body not making changes is also a bad idea.

TL;DR: This is something we need to pay attention to as a side-effect of geopolitical and economic policies.

How does early puberty effect employment? My interest is peaked.

General psychosocial effects on performance in school which directly impacts employment prospects. The link isn't direct, but it's there.

https://psychlopaedia.org/learning-and-development/puberty-a...

https://www.apa.org/monitor/2016/03/puberty

How do we know it's not some other, vaguely related environmental factor? For example pesticides carried by dust bowls would surely take more impact on states that got a lot of unemployment during that time.

The war in Ukraine and Russia, the pandemic, lockdowns, the economic crisis. I mean this era we’re in should be called the Great Methylation.

This is honestly still pretty mild by historical standards. With the possible exception of the covid lockdowns, but a year and a half is not actually that long. It sucks, but compared to the long term stresses people have suffered before, it doesn't stand out. We'll be lucky if the early 2020s stand out enough to be so named.

You would be "lucky" to be taken seriously when comparing 1.5 years of recent history with other well-known periods that most people think of as decades in length.

When we thematize World War II we start many decades before the first gun shot.

The events in Tigray alone, once the internet is restored and the full extent of the damage can be assessed and broadcast to the world, alone will probably be enough to give the early 2020s a name. When the worst mass atrocity in a generation can go on because the rest of the world had so many other problems to deal with, and so few people knowing about it, it highlights how bleak this period has been.

> not actually that long

It may appear so if you look at the more above-surface phenomena without checking the trends behind the underlying causes.

Already that which some now call "shrinkflation" is a 15 years old phenomenon, and it is far from being at the end of the analysis: it shows cultural crisis, decadence, an economic crisis which reveals the fragility of a system, not fixed in spite of former crumblings.

> it doesn't stand out

There is an interpretation of the formula that reinforces the above: appearances, over-the-surface phenomena "stand out". You see the above but supposedly look at the below, in the "underground", the causes. If you don't, there's another bad trend for the record.

Shrinkflation has been around for a lot more than 15 years. This Andy Rooney clip is from 1995, and looks at a trajectory of paper towel and toilet paper shrinkage since the 1970s: https://youtu.be/Q1lukmmJOHo

> Shrinkflation has been around for a lot more than 15 years

Sorry: I meant to point to the "accelerated" phase, very evident in some territories (with banners around claiming "We are keeping your prices down" and low quality new merchandise just below, for example), that seemed to start with the 2008 crisis.

Okay. I seemed to have not noticed anything particularly new starting around then. But I take your word for it.

It depends on where you have lived. In Europe, it seems to be wedged into a different world. One of the latest: they now sell shoes with hollow soles for heels to hit on thickness-providing blades: "It makes them lighter", I am told by clerks. "It is a public health concern and they would have been banned by the Authorities just not long ago, just before this unclear point of transition when it seems they don't anymore", one replies.

But anyway the point was exactly about those "peaks above the clouds" that have a whole mountain below, and then some Himalayas as its base...

Now that you mention shoes, I see your point. I got some very bad, very cheap shoes a couple of years after 2008.

or "Another way to explain the surging deaths of seniors when Cuomo was in office."

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