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Roman Empire's use of lead lowered IQ levels across Europe, study finds

theguardian.com

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Re: Roman Empire's use of lead lowered IQ levels across Europe, study finds

#51

Post by nahnahno »

curmudgeon22 wrote: post #3

> On average, lead levels in children’s blood at the peak of the Roman empire could have risen 2.4 micrograms per decilitre, the researchers found, reducing their IQ by 2.5 to 3 points. When taking background lead into account, childhood blood levels may have reached about 3.5 micrograms per decilitre. > A 2021 study by the Centers for Disease Control and Prevention in the US found blood levels in children aged one t…

2.5-3 micrograms per deciliter is nothing. Wouldn’t even come up as elevated by current childhood screening guidelines. I very much doubt 2-3 IQ point difference.

Re: Roman Empire's use of lead lowered IQ levels across Europe, study finds

#52

Post by bpodgursky »

thaumasiotes wrote: post #23
curmudgeon22 wrote: post #3

> On average, lead levels in children’s blood at the peak of the Roman empire could have risen 2.4 micrograms per decilitre, the researchers found, reducing their IQ by 2.5 to 3 points. When taking background lead into account, childhood blood levels may have reached about 3.5 micrograms per decilitre. > A 2021 study by the Centers for Disease Control and Prevention in the US found blood levels in children aged one t…

> reducing their IQ by 2.5 to 3 points I seem to recall reading an article that observed that every time we do a study of the effect of lead exposure on IQ, it gets larger. IQs aren't changing much, but lead exposure is going down, and so we keep imputing the same IQ gaps to ever-smaller quantities of lead.

People are downvoting, but yes this is accurate.

There are confounders between houses with lead and other demographics and contribute to the gap and aren't completely controlled — aspects of social class and low mobility that are hard to explicitly capture, it's all old housing.

So as the lead level drops and the gap remains steady (increasingly dominated by the confounding factors), more and more IQ gap gets attributed to the small lead-level gap between those living in old housing with abated lead pipes + paint and new pipes + new paint.

Re: Roman Empire's use of lead lowered IQ levels across Europe, study finds

#53

Post by CyberDildonics »

davorak wrote: post #31
CyberDildonics wrote: post #21

Earlier quoted context omitted.

Lots of people across the world don't have fluoride in their water, you could compare populations right now. https://en.wikipedia.org/wiki/Water_fluoridation_by_country

I doubt you can do a clean comparison, likely too many confounding factors, at least to pull anything out easily.

If someone thinks they can figure out 1500 years from now if the 'fall of the west' was because of fluoride, it's probably easier to look at the countries in the west that do and don't use it now.

Re: Roman Empire's use of lead lowered IQ levels across Europe, study finds

#54

Post by martinpw »

pea wrote: post #34
PeterHolzwarth wrote: post #15

I have no idea if this is true (and honestly can only barely remember the reference, which I read maybe a decade or two ago), but I believe I saw a comment that the interior of lead pipes eventually develop a "calcified" (don't know what else to call it) lining of the lead reacting to water, such that lead stops leeching into the water that passes through the pipes. I believe this came up when reading something about…

Yes, the piping in my parents’ house is all lead, but not worth replacing due to the above. It’s pretty common in old houses in Britain

Very interesting. I recently found out the house I grew up in in the UK over 15+ years had lead pipes that were never replaced, and I always wondered why they were not replaced and if it had some cognitive impact. This lining effect likely explains the reason, and offers at least some reassurance.

Re: Roman Empire's use of lead lowered IQ levels across Europe, study finds

#55

Post by hodgesrm »

PeterHolzwarth wrote: post #49
peeters wrote: post #46

> Roman Empire’s use of lead lowered IQ levels across Europe, study finds I'm not a fan of this phrasing. None of the findings had anything to do with measuring IQ levels in ancient Europe. They were about measuring historical levels of lead, which they then just plugged into modern models to presume some levels of cognitive effects. A study that was actually able to measure cognitive disparities and correlate them w…

Fully agree, @peeters - as I've mentioned elsewhere in these comments, there's a long-standing trend of trying to identify the one true cause of the fall of the Roman Empire. Each explanation falls short - it's just a complicated thing (and heck, the empire didn't really fall, it just shifted east.)

Or as some wag once put it, the empire then continued to decline and fall for another 1000 years.

Re: Roman Empire's use of lead lowered IQ levels across Europe, study finds

#56

Post by User23 »

pseudolus wrote: post #5
leptoniscool wrote: post #2

I wonder if future historians will see a similar drop after widespread use of plastic

Perhaps not with respect to IQ but there’s a chance that future historians might correlate the use of plastics with increased rates of infertility.

Next do fluoride.

That’s been “debunked” though right?

Re: Roman Empire's use of lead lowered IQ levels across Europe, study finds

#57

Post by Ferret7446 »

I can't help but be pedantic and point out that since IQ is normalized, their average IQ would be 100 whether or not they used lead.

More philosophically, the condition of life is inherently susceptible to damage, so you practically have to draw the line at what level of damage you want to try and mitigate given the realities of the time. Do you want to be wrapped up, only breathing, eating, and drinking perfectly calibrated mixes of chemicals?

Re: Roman Empire's use of lead lowered IQ levels across Europe, study finds

#58

Post by sebmellen »

__MatrixMan__ wrote: post #27
sebmellen wrote: post #14

Earlier quoted context omitted.

Anogenital distance is likely the preferred measure. > Males with a short AGD (lower than the median around 52 mm (2 in)) have seven times the chance of being sub-fertile as those with a longer AGD. > Swan et al. report that the levels of phthalates associated with significant AGD reductions are found in approximately one-quarter of Americans tested by the Centers for Disease Control and Prevention (CDC) for phthalat…

I was imagining something a bit more impactful (and easy to find in the data), because as far as that one goes, it's not clear why anyone should know or care. Maybe high school graduation rate (an inverse proxy to indicate bullying)?

Obviously not as easy to screen for, but this is a very clear indicator of how strong the known adverse effects of plasticizers are.

Re: Roman Empire's use of lead lowered IQ levels across Europe, study finds

#59

Post by adzm »

lostlogin wrote: post #48
pea wrote: post #34

Earlier quoted context omitted.

Yes, the piping in my parents’ house is all lead, but not worth replacing due to the above. It’s pretty common in old houses in Britain

If the water PH changes, the value in replacing those pipes might become more apparent.

But my sweet water!

Re: Roman Empire's use of lead lowered IQ levels across Europe, study finds

#60

Post by somenameforme »

trimethylpurine wrote: post #42
thaumasiotes wrote: post #23

Earlier quoted context omitted.

> reducing their IQ by 2.5 to 3 points I seem to recall reading an article that observed that every time we do a study of the effect of lead exposure on IQ, it gets larger. IQs aren't changing much, but lead exposure is going down, and so we keep imputing the same IQ gaps to ever-smaller quantities of lead.

IQs aren't changing much Isn't IQ a comparative representation of one's standing within their contemporary age group? My understanding is that within a given group the median should be 100. So you won't see it change between groups. This is highly relevant when you're talking about different groups being exposed to different concentrations of lead. As an extreme example to make the point, if people born in 1970 were…

You're right about how IQ is measured with 100 being the average and, generally, 15 points being a standard deviation. But numerous tests also record raw scores and these can be compared between generations. Scandiland and other places with compulsory conscription + IQ testing are the goldmine here. This is what led to the observation of the 'Flynn Effect' - the observation that IQ between generations was increasing, and later to its apparent reversal that generally started sometime around 1990 in the developed world. [1] That paper reports a later date, because it's about America in which studies on this topic lagged substantially behind Europe.

It's not easily explained by things like immigration since it is also present (though less pronounced) even within families. The hypothesis I find most compelling is that IQ levels have "naturally" been declining for decades, but improvements in nutrition, education, etc were helping to offset, and even rise beyond, these declines. But as nutrition, education, etc reach the point of diminishing returns, the declines dominate.

[1] - https://www.sciencedirect.com/science/article/pii/S016028962...

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