The Most Surprising Thing I Learned Today

The most surprising thing I learned today comes from the opening paragraph of a paper by Anne Case and Christina Paxson:

In late 19th Century Europe, adult height was attained at age 26.

This is just one reminder of how radically life has changed in the last 100 years. At least in the developed world, we have moved from a life of subsistence to a life of luxury.

The rest of the Case and Paxson paper, titled “Stature and Status: Height, Ability, and Labor Market Outcomes,” is interesting, too. Dubner tangentially mentioned this paper in a post a while back, but I think it deserves even more discussion.

It is well documented that tall people tend to hold high-status jobs and earn high wages. There are many possible explanations for this: height is a useful job attribute for some reason; other people mistakenly think tall people are more intelligent than they really are; being tall in high school gives you the confidence to succeed in the work force; etc.

Case and Paxson suggest a completely new explanation for the link between height and high wages: taller people earn more because they are smarter on average. They document that, as early as age three (before schooling has had a chance to play a role), taller children perform significantly better on cognitive tests. These higher scores persist through childhood. I find their evidence pretty convincing — though this is not good news for my four year old son, who is currently in the 5th percentile for height, just like I was at his age.

It is not often that someone tackles a commonly-researched problem and is nonetheless able to offer a new and convincing alternative explanation. I offer them the highest compliment I can think of: I wish I had thought of that!


What? This isn't a new hypothesis is it? I could swear I've heard this already...


I went to law school. Everybody was short. I'd like to see a study of the height of lawyers versus the average population. It would be fun to see a study of height by occupation generally.


I love the tendency you Americans have to create and use all sorts of statistics... Funny! But does comparing height with so-called intelligence testing scores make any sense? I mean, really.


So now short people can be ridiculed for having a Napoleon complex AND being less intelligent.

J Potter

How tall are you now Steven?


Since the Dutch recently overtook the Americans' top spot in being the tallest people in the world, does this also hint at us being smarter than you guys these days? (I live in the Netherlands.)

Furthermore, how does this compare to the fact that on average Asians score a higher IQ than Western/Caucasian people? Whereas the average Asian tends to be a lot smaller than most Americans and Europeans...

Or did the research concern only better results for tall people relative to their own peer group?


I went to law school. Everybody was short. I'd like to see a study of the height of lawyers versus the average population. It would be fun to see a study of height by occupation generally.

My guess is that taller people, men at least, are more likely to be found in sales-related jobs.


As a counter argument, what is the average intelligence among players in the NBA, MLB, and NFL? These players are on average taller than the general population and stereotypically much less intelligent.

Ciaran McNulty

"I went to law school. Everybody was short. I'd like to see a study of the height of lawyers versus the average population."

JP - I'd similarly like to see a study of the intelligence of lawyers versus the general population :-)


Uhm, I don't think that examining any correlation that may exist at a young age is a good way to determine if there's a correlation. At a young age, height is not fixed. Naturally, when children under 18 are included height can measure how far along they are in development, not any intrinsic characteristic.


Can the apparently under-employed Freakonomics staff really not come up with anything better than this?

Height is partly determined by environmental factors such as early childhood nutrition and quality health care to prevent and/or treat certain illnesses. These environmental factors are partly determined by the family's socio-economic situation.

In addition, higher income families have an easier time guiding their children (through a combination of educational and social networking opportunities) into the higher-paying professions.

In other words, the common denominator between height and higher incomes is the socio-economic status of the child when s/he grew up.

Ditto with higher IQ scores - socio-economic factors (early childhood nutrition, formal and informal education) play a significant role.

But height itself - independent of socio-economic context - is unlikely to be a determinant of future earning potential.

Mystery solved. Everyone go home now.


jonathan Kurtzman

I know that in WWI, the officer class was about 6 inches taller and a large number of pounds heavier than the draftees from the cities. Nutrition for the well off and, as Jack London described in People of the Abyss, starvation lurked for many of the rest. No wonder people didn't reach full height until later and no wonder one can link intelligence to stature; poor nutrition damages the brain. BUT, the nutrition differences expressed physically led to a general feeling that the better classes were meant to be better, meaning that the class system sought a "scientific" explanation. This tainted thinking influenced the eugenics movement.

There is a wonderful book that describes the low intelligence of immigrants, notably the Jews from Eastern Europe. There is also a book which describes Austrian-German views about the limits of Jewish intelligence, that they were capable of imitation (holy Wagner, Batman!) but not innovation. Same eras, but some Jews were fed enough to show their brainpower. The idiots of the era assumed the eastern Jews were of a lower stock.

Height is a marker for the young person's ability to ingest nutrition. Being small can be labeled "failure to thrive" syndrome and one consequence is often learning issues. I have not spent any time going through the data, but I would assume the lower scores of the smaller end would be real. It may be that taller young children metabolize better and that this affects their brains.

As to the rest of the life . . .



ciccina is right


What if height correlates to health instead of intelligence? Good nutrition, absence of stress, and regular exercise have positive effects even on babies and toddlers (especially on babies and toddlers). Isn't intelligence also dependent on these variables?
I think height and intelligence are coincident with health. To respond to Serge's observation, it stands to reason that wealthy countries (such as the US and the Netherlands) are better able to provide nutrition, appropriate healthcare, vaccinations, and education to parents to nurture their kiddos. Hence, gains in height and intelligence.


If height is related to nutrition and assuming intelligence is at least somewhat hereditary, wouldn't it make sense that on average intelligent parents would find ways to feed their children better and therefore make them taller?

David R.

I remember but am not able to locate a WSJ article about how the more successful NFL teams have players with higher IQs. Athletes are more intelligent than average. Good looking people are more intelligent than average, too.

Are the stereotypes of stupid models, football players, and actors are reinforced by "news" because that is what people want to believe?


Well, Duh... Toddlers come in all sizes, but underneath the statistical noise there's a correlation between being a 'tall' three-year-old and good diet, good health, a stimulating and emotionally-supportive family environment, and - above all - the absence of all the bad things that contribute to low birth weight.

That last factor is well known to be correlated with IQ. And, for that matter, just about everything we can measure in terms of 'life outcomes'.

Nevertheless, I was as surprised as you are by the phrase 'attained at age 26'; I had believed that the epiphyses - growth in the long bones - became inactive in an individual's late teenage years.

andrea volterra

then NBA players average IQ should be higher than that of a random sample of people the same age. i bet it's not


The fact that the taller children scored better could just be that they were more physiologically developed than their peers. This could presumably mean that on average their brains had also developed further, accounting for the difference in scores.

David R.

Andrea (#18)- There may be a few NBA players who succeed despite their lack of intelligence, and perhaps these players get more than their share of TV time. But, the idea that the average IQ is low for the elite level of players in a team game is unsupportable.