July 24, 2013

IQ and Iodine in WWII

The World's Awesomest Newspaper reports on a study from a few years ago:
In a report published in the National Bureau of Economic Research, James Freyer, David Weil and Dimitra Politi examined data from about two million enlistees for World War II born between 1921 and 1927, comparing the intelligence levels of those born just before 1924 and those born just after. 
To do this, they looked to standardized IQ tests that each recruit took as a part of the enlistment process.

While the researchers didn't have access to the test scores themselves, they had another way of gauging intelligence levels: smarter recruits were sent to the Air Forces, while the less intelligent ones were assigned to the Ground Forces. 
Next, the economists worked out likely iodine levels in different cities and towns around America using statistics gathered after World War I on the occurrence of goiter. 
Matching the recruits with their hometowns showed researchers that the men from low-iodine areas made a huge leap in IQ after the introduction of iodine. 
The men born in low-iodine areas after 1924 were much more likely to get into the Air Force and had an average IQ that was 15 points above that of their slightly older comrades. 
This averages out to a 3.5 point rise in IQ levels across the nation.

You can see something of a Flynn Effect in the historical record of conscription in the two world wars. American elites were shocked by what a sizable fraction of draftees in WWI were illiterate and/or kind of slow. WWII draftees were somewhat more satisfactory to the big shots. 

In particular, mechanical skills were very good. Thanks to Henry Ford, et al, young American men entered the military in WWII knowing more about repairing internal combustion engines than any other country's soldiers. In contrast, the Japanese started the war in the Pacific with elite technicians capable of bombing Pearl Harbor, but they couldn't ramp up the numbers anywhere near as fast 

But, I hadn't been aware of this 1924 bump.

Kiwanis International is the main charitable supporter of iodizing salt in poor countries.

I'm going to take some days to do some work around the place, so comment moderation gatekeeping  will lag. You might consider not posting comments until I resume regular posting
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21 comments:

Chief Seattle said...

Does Vietnam have iodized fish sauce?

Peter the Shark said...

"young American men entered the military in WWII knowing more about repairing internal combustion engines than any other country's soldiers."

It's true, and I think Ambrose tries to make a big deal of that in one of his books - but I don't see how that had much of an effect on the war. Sure, the average German probably wasn't as good at improvising some quick fix to a balky truck or tank engine in the field as the average American soldier, but a far bigger problem for the Germans was the lack of adequate numbers of tanks, trucks and drivers in the first place, and lack of fuel was an even bigger issue.

James Thompson said...

Couldn't find the paper, so no capacity to comment on this interesting estimate. Seems a bit improbable to me, just at the moment.

stari_momak said...

1) Kiwanis. I'm sure that Steve, as a promising young man, was a member of Key Club in high school. I was. Pretty good exemplar of social capital. The Kiwanis guys we were associated with weren't world beaters. Most had pretty ordinary, middle class jobs. But they gave their time to make their community, and the world, a better place. They had a good time along the way, but they also really contributed to social capital.

2) Goiter. Anyone notice that both Rachel Jeantel and Trayvon Martin's mother had a...something...about their necks that resembled goiter.

stari_momak said...

Someone noticed on Jeantel.

https://www.facebook.com/thelastword/posts/514480368606814

David Davenport said...

... between 1921 and 1927 ...

Congress passed the Immigration Act of 1924.

Anonymous said...

I'm still thoughtful, IQ actually measures the 'real intelligence'*?
* True Intelligence = intellectual curiosity.

Anonymous said...

The West is full of praise for mendacious Mandela.
We are told that Mandela steered SA from massive bloodshed.
But imagine there's 'peace' between Jews and Palestinians in Israel/Palestine, and the levels of violence against Jews are on the level of anti-white violence in SA since end of apartheid. Would the 'liberal' media be praising the 'peace' and be pretending all is hunky dory and getting better?

Truth said...

"I'm going to take some days to do some work around the place, so comment moderation gatekeeping will lag. You might consider not posting comments until I resume regular posting"

Hey Komment Kontrol Jerk; "The cat's away!"

Anonymous said...

How much is Liberal compassion related to fear?

White Liberals fear blacks but they don't fear pudgy short hispanics like Zimmerman.
o, they to try to soothe black rage with expressions of outrage but viciously bark at Zimmerman as evil white guy though he had a black business partner, tutored black kids, defended a homeless black guy against the police, and took a negress to the prom.

Mark Plus said...

Don't people who live in coastal areas like the Florida peninsula get enough iodine from the salts in ocean mists?

Mark Plus said...

The IQ testing during the Second World War probably gave the government a good reading on the cognitive abilities of the young adult male population and showed how many men from the gutter could benefit from higher education. I suspect these data played a role in including college assistance in the G.I. Bill of Rights.

My father, an Oklahoma farm boy, turned 18 in 1945, and the Army Air Corps drafted him, despite the powering down of the war that year. Based on his IQ test, the Air Corps trained him as a cryptographer, which says something about his cognitive abilities at the time. He didn't have to leave the U.S., and he got an honorable discharge in a few months. But he qualified for G.I. Bill benefits, and he used them to go to the University of Oklahoma to earn a pharmacy degree.

ScarletNumber said...

or you could just turn off moderation

Anonymous said...

http://dailycaller.com/2013/07/25/race-relations-have-plummeted-since-obama-took-office-according-to-poll/

sheeeeeeeeeeeiit

pat said...

Cretinism has been a problem in southern Europe as long as it has been inhabited. There isn't enough iodine in the soil.

In the sixties the great American baritone Cornel MacNeil when singing in Parma got disgusted with the audience booing the tenor. He advanced to the footlights and yelled at the audience "Basta cretini".

Being called cretin in Italy was still a familiar insult then. The audience came out of their seats after him and they duked it out on the stage. MacNeil we're told did well in the fisticuffs. His nickname was always "Big Mac".

Cretinism died out with government actions and the increase in imported food. It had been that whole isolated towns in the Italian Alps were filled with nothing but cretins.

Albertosaurus

Anonymous said...

Did Beavis and Butthead ever make a crack about Boeing airplane company by saying 'boing!!'?

Gringo said...

Anonymous @7/25/13, 7:46 AM
How much is Liberal compassion related to fear? White Liberals fear blacks but they don't fear pudgy short hispanics like Zimmerman.

Similarly, liberals have no problem with those who trash Christianity- think Piss Christ- but do have a problem with those who trash Islam. Again, a fear factor.

Anonymous said...

Liberals keep looking at the distant past when there was plenty of low hanging fruit in the IQ game - offer free public education to immigrants, correct a few nutritional deficiencies, and viola, IQ has gone up. Nowadays we keep spending more and more billions on free school lunches, expensive school systems and yet the numbers never budge. Gee, I wonder what has changed? I have no idea....

K

Anonymous said...

Cretinism has been a problem in southern Europe as long as it has been inhabited. There isn't enough iodine in the soil.
...
Cretinism died out with government actions and the increase in imported food. It had been that whole isolated towns in the Italian Alps were filled with nothing but cretins.


Here is the etymology of "cretin", from Wikipedia:

The etymology of cretin is uncertain. Several hypotheses exist. The most common derivation provided in English dictionaries is from the Alpine French dialect pronunciation of the word Chr├ętien ("(a) Christian"), which was a greeting there. According to the Oxford English Dictionary, the translation of the French term into "human creature" implies that the label "Christian" is a reminder of the humanity of the afflicted, in contrast to brute beasts.[1] Other sources suggest that Christian describes the person's "Christ-like" inability to sin, stemming, in such cases, from an incapacity to distinguish right from wrong.[2][3]

There could also be a connection to Crete; though iodine deficiency is more Alpine than coastal Mediterranean.

gwern said...

Chief Seattle: Vietnam has official iodization programs, but they're not very successful. However, they probably aren't as bad off as one might expect because they're such a coastal nation and all the seafood will generally increase iodine intake.

James Thompson: this paper is totally plausible. Iodization has huge effects on IQ; it would be bizarre and weird if oen *couldn't* find some sort of effect like this. In any case, there's a draft version of the findings at "The Economic Effects of Micronutrient Deficiency: Evidence from Salt Iodization in the United States" http://www.dartmouth.edu/~jfeyrer/FeyrerPolitiWeil_iodine.pdf and the fulltext can be found at http://ge.tt/7Lwdwlj/v/1 (but no guarantees this link will stay up).

David Davenport: er, and how many people were immigrating per year? Just run the numbers, even if you're incredibly pessimistic about immigrant IQs, you simply can't get this huge a boost on a national level just from shutting down immigration.

pat: and the Swiss Alps, too. Some of the most striking iodine research was done in Switzerland because some of the regions' soil were *so* deficient.

---

If anyone is interested in the general topic, I've compiled some of the relevant literature in http://www.gwern.net/Iodine (toward a meta-analysis of iodine's post-natal effect on IQ, which seems to be ~0).

G.H. said...

Could endemic iodine deficiency explain why Armenia has unimpressive average IQ despite a respectable (and presumably well nourished) smart fraction?