Is IQ what is truly scarce?

There is a new view — or should I say an old view? — percolating in the blogosphere: "There is something special about IQ.  We must conserve IQ at very high cost, and gains in IQ will bring very high social returns." 

In practical terms, "Conservation of IQ" is used to argue for limits on immigration, against various meliorist attempts, and possibly even for eugenics.  I’ve heard it used to argue for outlawing marijuana, which of course destroys brain cells.

Imagine an evolutionary approach: given the Industrial Revolution and subsequent developments, perhaps IQ has higher social returns than was once the case.  So we must rebuild our intuitions to favor IQ more than otherwise.  When evaluating policy, one question is simply to ask whether it raises or lowers average IQ within a polity or region.

There is also a methodological argument: IQ is (arguably) prior to economic notions of rationality.  Perhaps economists should treat rationality as an open variable and dependent on IQ.

I don’t assign special status to The Conservation of IQ for two reasons.  The first is the Flynn effect, or the fact that measured IQs have been rising steadily over time.  This implies some combination of a) IQ gains come naturally under conditions of progress, and b) IQ statistics are to some extent phony and don’t measure real intelligence.  We can debate the mix, but either deflates fears that IQ is somehow especially scarce or endangered.  These data also suggest that IQ is an artifice to be unpacked rather than a primary category.

Second, defenders of the IQ view tend to read evolutionary biology and intelligence research.  My roots are in cultural history.  Clusters of amazing achievement come and go pretty quickly, usually through some mix of environmental effects and luck.  Look at Venetian painting.  It was much better centuries ago, but I doubt if Venetian IQs have been falling.  Once we see how such enormous differences can be explained by non-IQ factors, I again don’t obsess over the variable.

I do think economists should study IQ more.  And for sure I value it in friends.  But when analyzing social problems, institutions, social psychology, and economic mechanisms still command most of my analytic attention. 

A few of you had asked about IQ, I crammed my thoughts into this one post, so this is #04-07 in a series of 50.  Do, by the way, save your thoughts on immigration for other posts.


Steve Sailer must have made it into the top fifty, then.

"IQ" seems to hold the same meaning for some conservatives that "social class" holds for some liberals. It's this hard-to-measure phenomenon that separates everyone into groups that they can't do much to get out of.

"b) IQ statistics are to some extent phony and don't measure real intelligence."

I'm not sure why you would take the Flynn effect to mean this. IQ is supposed to measure intelligence, not the inherent capacity for intelligence at conception.

Paul Graham asks a similarly interesting question in his book Hackers and Painters.

He wonders how many Leo Da Vincis are currently walking the earth, but who are without
a Florence in which to flourish. I would guess that there are at least 5 Da Vincis in
the US alone, all of whose talents are untapped.

Traits like courage, ambition and persistence in the face of adversity may be as important as IQ and they may enhance the positive benefits of high IQ. Perhaps they should be measured as well. Or does the IQ concept incorporate them?

The first is the Flynn effect, or the fact that measured IQs have been rising steadily over time.

Maybe. The wikipedia article does note that there is evidence suggesting that in England and Continental Europe, the Flynn effect ended sometime in the 1990s, and that there has subsequently been moderate regression. So I'm not sure we can count on that.

As far as cultural factors, yes, I think those are important, as you note. But we have little to no control over cultural factors, and we can't measure them yet in any event. All we have is generalities there -- vague ideas that this incentive will encourage that positive behaviour and so forth. On the other hand, I think that ceteris paribus, living in a high IQ society (or perhaps a society dominated by high-IQ individuals) is preferable to a low-IQ society.

It seems pretty clear that _at best_ IQ measures not one thing but a strange and unreasonable grab-bag of skills, no one of which has any special connection to what people hoped IQ would do. (Binet, to his credit, seems to have understood that much better than the Stanford folks who made the modern Hash out of his works.) There are many, many things wrong with most discussions of IQ, but the fact that it's not a single or natural thing is what's most deeply wrong with most of them.

Perhaps another reason not to "assign special status to The Conservation of IQ" is that most of the people talking about the issue have high IQs and therefore will be inclined to think that high IQ is more precious or more important than it really is.

IQ may well be scarce, but the notion that there is such a thing as "the truly scarce resource" has no basis in economics or logic. A lot of people seem to be confusing IQ numbers with general human capital, which is indeed extremely undervalued - phasing out our dysfunctional public schools in favor of a voucher-based system would remedy this.

Michael -- I'm willing to buy that for visual artists and maybe even composers, but do you really think it's true for writers? It's hard for me to believe that someone could be a great novelist or poet (at least before about 1920 w/r/t poets) without having a high IQ.

dk above, i think hits the nail on it's head.

In practical terms, "Conservation of IQ" is used to argue for limits on immigration, against various meliorist attempts, and possibly even for eugenics. I've heard it used to argue for outlawing marijuana, which of course destroys brain cells.

What a load of collectivist nonsense. IQ may be valuable in some special way or it may not, but regardless of any of that, my IQ belongs to me, and that means I have the right to use it, or not, or move it around, or destroy it if I so choose. To argue otherwise is to claim that I belong to the state, which is the most morally repugnant notion ever conceived by man.

There is a good article by Linda S. Gottfredson that talks about IQ and g in the context of education issues. See

Seems to be quite consistent with everything I've read in this area, and is a good summary.

"...marijuana, which of course destroys brain cells"

Really? Could you cite any research?,2933,172194,00.html

Many of the important inovation are made by people with outstanding ability in a particular area, but are quite ordinary in other respects. IQ is the "average" of many seperate abilities, and a weakness in one will often produce extra effort in developing other abilities where there is a greater possiblity to excel. Many physicist are poor spellers and had trouble learning to read (even Einstein), while professional writers often show a weakness in the understanding of even basic math. This may be a part of the reason that "high" IQ people often do not fulfill their potential. Real accomplishment takes effort and focus as well as ability, and being good at everything, which is needed to score really high on an IQ test,is not always an advantage.

So many fallacies†¦

1. The importance of IQ is an empirical matter. Whatever your ideological beliefs may be it is impossible to deny that IQ is the single best predictor of academic and economic success. Singe best predictor does not mean it explains everything, or close to everything. But more than hundreds of other variables people use.

2. The fact that IQ tests are an imperfect measure of true IQ is an argument for the importance of true IQ, hardly the opposite.

If *imperfect* measures of intelligence are the best single predictor of success in life, than logically true IQ is EVEN MORE IMPORTANT than what IQ-tests imply (essentially some of the variance is explained by variance in the test).

3. The premium for skill has been rising over the last 30 years. Some people mention human capital above. Both these measures are strongly linked to IQ.

In one of Murrays comparisons of Siblings with a sample of about 1000 people he found that

0% of those below 75
3% of those with IQ 75-89,
19% of those with IQ 90-110 went to college,
82% of those above 125.

These are staggering figures. It is simply silly to have a discussion of economic inequality in America and not mention IQ. By the way, unlike “class† intelligence is a well defined, consistent and measurable variable. Cowen is the one that is being fluffy here. It is furthermore nothing more than a straw-man that IQ should be able to explain everything to matter. It explains a lot, in a world where most social behaviour is hard to explain.

I would bet any amount of money that there is not one person in the Geroge Mason economic faculty that would score lower that average on an IQ test. I would even bet that there is almost not one person commenting here which belongs to the left half of the bell curve.

Do you think that is a coincidence? After all, if IQ is not that important, why do we observe these systematic patterns?

I'd like to riff on MIchael Blowhard by arguing that IQ isn't the real issue. I have become convinced that achievement is based primarily on hard work. certainly an above-average IQ is helpful in many areas, but it does not lead to what we think of as 'genius' - i.e. high-level achievement, which is the product of deep thought and hard work.

for further thoughts on this I'd check out the blog of author David Shenck, who's working on a book on this (I think he overstates the case for nuture, but I think some of his arguments are compelling).

1) IQ doesn't measure everything about intelligence. Which is why people with extensive brain damage who can't run their own lives well enough to stay out of prison can still have very high IQ scores.

2) There are societies in which people of average intelligence -- including those at the low end -- can do things which in other societies are considered to require high IQs. Playing musical instruments, speaking two or more languages fluently, composing poetry, etc.

Which suggests we're not making full use of current resources.

You do not know how Adam Smith, Watt, or Einstein scored on a IQ test, you are assuming your conclusion that people who make important contributions perform unusually well on IQ test.I know many Phd physicist who do not score very much above arerage on on IQ tests because of weaknesses in some of the subtests.

The dependence of income on IQ disappears when a regression includes education as one of the variables. If high IQ people were really scarce they would earn more, even without an education. The premium is paid for education.

From Adam Smith to Watt to Einstein to Kilby to the scintists that drive technologi today IQ has been a neccesary (of course not sufficient, but that hardly makes it less important) factor of production.

Whoa, I didn't know Adam Smith got his IQ tested! You learn something new every day.

"The difference of natural talents in different men is, in reality, much less than we are aware of; and the very different genius which appears to distinguish men of different professions, when grown up to maturity, is not upon many occasions so much the cause, as the effect of the division of labour. The difference between the most dissimilar characters, between a philosopher and a common street porter, for example, seems to arise not so much from nature, as from habit, custom, and education. When they came into the world, and for the first six or eight years of their existence, they were perhaps, very much alike, and neither their parents nor playfellows could perceive any remarkable difference. About that age, or soon after, they come to be employed in very different occupations. The difference of talents comes then to be taken notice of, and widens by degrees, till at last the vanity of the philosopher is willing to acknowledge scarce any resemblance.

As it is this disposition [to truck, barter and exchange] which forms that difference of talents, so it is this same disposition which renders that difference useful. Many tribes of animals acknowledged to be all of the same species, derive from nature a much more remarkable distinction of genius, than what, antecedent to custom and education, appears to take place among men. ... Those different tribes of animals, however, though all of the same species, are of scarce any use to one another. ... Among men, on the contrary, the most dissimilar geniuses are of use to one another; the different produces of their respective talents, ... being brought, as it were, into a common stock, where every man may purchase whatever part of the produce of other men's talents he has occasion for."


We are not “assuming† that Einstein and Smith had high IQs, we can infer it from their life history. I do find it amusing how much people are willing to decieve themselds to deny IQ. Anyone here honestly thinks Einstein and Adam Smith (that entered college when he was 15) had lower than averge IQ:s? If so than please make this claim openly.

There are no physics Phd in the united stated with low IQ. In order to be accepted at an physics Phd program you need to score high on the GRE. Basically no one that does not have a high level of intelligence can do this.
Case in point:

The average, AVERAGE, of people with intended graduate major in Physics is 740 math. Incidentally physics majors also score exceptional on the verbal part, despite the fact that many are not American (head of the g factor?). Given how restricted the range of people that take the GRE the average person that takes the GRE intending to study physics (presumably below the average person that actually gets accepted, let alone earn a Phd) is 135.
So they score low on a *part* of the test? Maybe this is why they invented factor analysis†¦

“The dependence of income on IQ disappears when a regression includes education as one of the variables. If high IQ people were really scarce they would earn more, even without an education. The premium is paid for education.†

This is a spectacularly stupid argument. The value of a fast computer processor would be 0 if you outlawed programming and hardrive. Does that make the processor useless?

I think it is entirely safe to say that there has not been very much, if any, selective preccures put on most human populations for the last couple of hundred of years. When populations explode, it means that everything is going through to the next generation. This doesn't mean that natural selection cannot occur in expanding populations, just that in extreme cases where environmental factors lead to incredible fecundity, they are much much less of a factor.

In this context, it is very, very difficult to argue that we can evaluate policies based on their effect on the IQ of the population.

Every top econ grad department use the heavily IQ-driven GRE to screen applicants.

And yet economists, as these economists, as these comments show, turn around and try to pooh-pooh the importance of IQ.

Something does not compute...

Mr. Sailer,

The effects of height disappear when one factors in years on professional basketball experience.

Anyone here honestly thinks Einstein and Adam Smith (that entered college when he was 15) had lower than averge IQ:s? If so than please make this claim openly.

Adam Smith openly stated that there was little difference in natural talents between a philosopher and a common street porter. As a professor in moral philosophy, this claim was presumptively based on introspection and experience - can you please list your evidence on the contrary?

As to the Flynn effect, I suspect a great deal of the increase was simply due to much better nutrition (and medicine) over the last century or two. We're several inches taller for much the same reason

Also, I believe even Flynn has stated the effects have stopped in the last couple of decades.

Indeed, according to We are about as smart as we're going to get, says IQ pioneer the Flynn effect is over, says Flynn. A quote

"Now the man who first observed this effect, the psychologist James Flynn, has made another observation: intelligence test scores have stopped rising.

"Far from indicating that now we really are getting dumber, this may suggest that certain of our cognitive functions have reached — or nearly reached — the upper limits of what they will ever achieve, Professor Flynn believes. In other words, we can’t get much better at the mental tasks we are good at, no matter how hard we try."


You claim I am using circular reasoning, simply because you don’t understand what I am saying.
But before I start let me just take a second and ponder the fact that there are people here several people seriously questioning the fact that Albert Einstein had a above average IQ.

It is not circular logic to empirical facts to infer that Einstein or Smith had high IQ. There is historical data about those individuals. To this we can link systematic patters of behaviour that are known today.
People that like Smith are able to complete advanced education at a young age almost without exception have very high IQ (and yes I realize that the education system was somewhat different back than). People that do advanced physics or score very perfect math grades (which Einstein did as a child) also tend to have above average IQ, almost without exception.

There is therefore nothing strange or circular in pointing out that both those individual almost certainly had high IQ.

There are no great physicist or great Economists today that do not have high IQ. Knowing this about humans today it’s just childish to reduce to accept that the pattern was not true historically. Einstein did not have a extraordinary high level of abstraction and general intelligence, and claim that his innate ability had nothing to do with his success as a scientist.

“can you please list your evidence on the contrary? [that there is difference in natural talents between a philosopher and a common street porter†

IQ is largely, but not completely genetic. We know this beyond any reasonable doubt through massive research, for example on identical and non-identical twins.

According to the consensus view of the Task Force established by the Board of Scientific Affairs of the American Psychological Association the heritability of IQ for adults is 0,75.

Even if this is not the exact figure there is not doubt that the heritability is substantially higher than zero. To the extent that you think a successful philosopher or economist needs a high level of abstract thinking there is a innate difference between the average person and the average top philosopher.

The first is the Flynn effect, or the fact that measured IQs have been rising steadily over time.

The Flynn effect is much debated. Some find surprisingly little evidence for any significant closure of the IQ gap. In a recent debate between Flynn and Murray, Flynn was noted for relying heavily upon intelligence test results for military personnel. The obvious problem here is that the military has altered the ASVAB substantially over the years. You can look around VDARE, Steve Sailer's site, and Gene Expression for some more reasons to call into question the idea that the Flynn effect will save us from idiocracy.

Steve Sailer points out one common sense objection to the Flynn Eefect.

Clusters of amazing achievement come and go pretty quickly, usually through some mix of environmental effects and luck. Look at Venetian painting.

Yes, look at Venetian painting. Look at any period of European cultural achievement. Just don't look at sub-Saharan Africa, then take a look back at Europe and East Asia, and then tell us the same thing.

I don't want to bring up the immigration angle, but needless to say, when it comes to any policy planning where IQ is concerned, those who are banking that we won't find genetically-based differences in intelligence among racial groups at the end of the day are taking one hell of a gamble with our future.

My problem is the way IQ is reduces to a single number that is then used to put people in boxes. Below is a list of subtest the are used to make up "IQ". If you look at the list,it is obvious that that someone could do very badly on some of them, which would lower their IQ, and still have the ability to get a Phd in physics or do well in many other fields. I do, in fact, know several physicist whos over all IQ score is in the average range. Einstein had diffculty learning to read so probably had some low scores on subtest that have high correlations with reading, but not with math.

stanford binet IQ test measures the following skills

Information: Similar to "Trivial Pursuit," this subtest measures fund of factual information. It is strongly influenced by culture. An American education and intact long-term memory will contribute to a higher score. Sample question (not really on the tests): "What is the capital of France?"

Comprehension: This subtest measures understanding of social conventions and common sense. It is also culturally loaded. Sample question: "What is the thing to do if you find an injured person laying on the sidewalk?"

Digit Span: Requires the repetition of number strings forward and backwards. Measures concentration, attention, and immediate memory. Lower scores are obtained by persons with an attention deficit or anxiety.

Similarities: This subtest measures verbal abstract reasoning and conceptualization abilities. The individual is asked how two things are alike. Sample question: "How are a snake and an alligator alike?"

Vocabulary: This test measures receptive and expressive vocabulary. It is the best overall measure of general intelligence (assuming the test-taker's native language is English). Sample question: "What is the meaning of the word 'articulate'?"

Arithmetic: Consists of mathematical word problems which are performed mentally. Measures attention, concentration, and numeric reasoning. Sample question: "John bought three books for five dollars each, and paid ten percent sales tax. How much did he pay all together?"

Performance Scales:

Object Assembly: Consists of jigsaw puzzles. Measures visual-spatial abilities and ability to see how parts make up a whole (this subtest is optional on the revised Weschler tests).

Block Design: One of the strongest measures of nonverbal intelligence and reasoning. Consists of colored blocks which are put together to make designs.

Digit Symbol/Coding/Animal House: Symbols are matched with numbers or shapes according to a key. Measures visual-motor speed and short-term visual memory.

Picture Arrangement: Requires that pictures be arranged in order to tell a story. Measures nonverbal understanding of social interaction and ability to reason sequentially.

Picture Concepts: A new subtest on the WISC-IV. Requires matching pictures which belong together based on common characteristics. Measures non-verbal concept formation and reasoning; a non-verbal counterpart of Similarities.

Picture Completion: Requires recognition of the missing part in pictures. Measures visual perception, long-term visual memory, and the ability to differentiate essential from inessential details.

Matrix Reasoning: (WAIS-III only) Modeled after Raven's Progressive Matrices, this is an untimed test which measures abstract nonverbal reasoning ability. It consists of a sequence or group of designs, and the individual is required to fill in a missing design from a number of choices.

If economists don't like IQ, why don't they rely more on non g-loaded tests, such as GPA, history tests on econ, multiple choice tests for economics. I think it's pure hypocrisy: economists are in practice closet IQ fetishists at research universities (I clearly remember Casey Mulligan being advertised and perceived as being a zero in terms of any current ideas, but a great hire because he's so frickin' smart, which he is).

Economists brag about their realism vs other social scientists via their assumption of self-interest. But they are wimps on realism relating IQ (remember the JEL fatwa on Herrnstein and Murray to advertise their PC bona fides). It's clearly politic to pick your battles. So be it, but it's still wrong, and cowardly.

The effects of height disappear when one factors in years on professional basketball experience.

Hmmmmm.....hmmmmm....lets think real hard about a possible reason for this which does not appeal to the strange notion that height simply doesn't matter in basketball.....


....hmmmmmmm.....this is such a perplexing one, but I'll hazard a a guess:

Maybe because players who cannot cut it have shorter careers.

If you're not very tall, you are at a disadvantage in basketball and are more likely to have a short career. In other words, you have to be exceptionally good as a short player to make it. Thus the level of individual success among basketball players, regardless of height, tends to converge over time. Just as you might expect when looking at practically any metric in any competitive field where the disadvantaged face elimination.

Just a guess.

This is utter garbage. Back in the 19th century. . . racist prejudices

The source of group differences is revealed by evidence and inference not morality.

Practice taking IQ tests. Or just do some biofeedback.

No, see these two recent papers. Practice effects are hollow score gains, not genuine improvements in ability.


Your problem is that you have no sense of humor or irony. The prospect of obviously high IQ people denying the existence of IQ should be a source of mirth, not outrage.

If IQ doesn't matter, then find me a nuclear physicist with an IQ of 85.

Help me here guys. A few years ago there was a study demonstrating that amazingly Ivy League graduates had on average the highest incomes. What the study also showed was that persons who did not go to Ivy League Schools but could have gone (met admissions criteria) earned just as much as the Ivy League grads. Would suggest that there benefits (signaling and social networks) to an Ivy league education, but ultimately IQ is what drives earnings (on average). Who wrote the study?

Jason Malloy,

Thanks for the links. I will have to peruse the studies more later. But, in terms of economic growth, I don't think it matters whether the gains are in a narrow task-specific domain or at the g-level. The division of labor alleviates this pressure. People only need to improve (become "smarter") at the narrow tasks they face.

I don't think it matters whether the gains are in a narrow task-specific domain or at the g-level. The division of labor alleviates this pressure. People only need to improve (become "smarter") at the narrow tasks they face.

Nope. The g factor is pretty much the whole story. Ree & Earles (1994) for instance found the correlation between g and job training success was 0.76. All the non-g portions put together added nothing to the prediction.

I have posted my own take on the original question:

Right. It's like how you couldn't have created the 1996 Bulls out of a bunch of random tall guys. On the other hand, you couldn't create any NBA team out of a bunch of guys of average height, no matter how fine all their other qualities. Thus, height is definitely a scarce commodity for the purposes of assembling winning NBA teams.

Similarly, in answer to Tyler's title question, "Is IQ what is truly scarce?" the answer is, of course IQ is scarce. Economics is the study of scarcity, so most everything is scarce to some extent. But, surely, any honest study of the world around us would suggest that IQ is one of key scarce factors along a host of dimensions. It's time for economists to start studying IQ.

Steve Sailer wrote recently about the basketball player John Amaechi, 6'-10'' and 270 pounds, who played terribly because he didn't like the sport and was only in it for the money. Now at that height this guy could have been a brilliant player if he put in the effort and trained himself a bit, but he had no motivation and felt no sense of purpose in what he was doing. However all must be agreed that he had the POTENTIAL, whereas most people's height renders them unfit to be a fantastic basketball player. I think this is what Steve means by the 'restriction of range' he talked about in an earlier post in relation to IQ.

Likewise with the highest art or learning. The average guy in the street is incapable of creating great art as he is outside the required range (spatio-visual IQ for painting, architecture, verbal for poetry, literature etc). But within the range there remains a great divergence in artistic accomplishment, and I think that is where Murrays four preconditions have an impact. Dante and Albert Camus both had high IQ's, but the preconditions for Dante (belief, purpose etc) were much more condusive to artistic accomplisment than Camus' (atheist nihilism), and so despite both being 'in the range', their final output was wildly different in terms of high beauty and greatness.

Tyler - 'Look at Venetian painting. It was much better centuries ago, but I doubt if Venetian IQs have been falling.' Murray's four preconditions ended after Napoleon took over and gave it to Austria, and it's hearty individualistic nationalism was eventually subsumed into greater Italy. Nationalism is a good artistic muse providing purpose and inspiration - Michelangelo sculpted the David as a symbol of Florentine nationalism.


Note that these claims are glaringly inconsistent.

The claim that IQ generally cannot be increased by practice and the claim that success in job training is heavily dependent on g are not contradictory in any way that is obvious to me.

The reason economists do not take IQ seriously is that they understand how tiny differences in _natural comparative advantages_ can be amplified by positive feedback effects

Well, do they understand anything about minimal requirements as Sailer has been pointing out using his basketball examples?

If amplified natural comparative advantages could explain the wealth of nations, we might expect a world where national wealth and national IQ were much less consistently correlated.

The naïve social Darwinism of intelligence researchers has been thoroughly disproven.

You'll need something other than your word to back that statement up.

Again, if IQ is meaningless, then find me a nuclear physicist, any nuclear physicist, with an IQ of 85.

One thing I think might be important here: you probably aren't as good as you think you are (for most values of "you") at evaluating someone's intelligence based on conversing with them. I know people in my own field whose work I can judge, who range from verbally quick enough to make a living as stand-up comics, all the way to people who almost need to take each sentence in a conversation offline and think about it for awhile.

It's really common to hear people say stuff like "well, I talked to these three guys, and they're not all that bright." But while I'm sure verbal quickness and obvious intelligence are correlated with real intelligence, they're not the same thing.

I think there have been experiments showing that listeners evaluate the intelligence of the speaker differently when the speaker has an English or Boston accent than when he has a Texas accent. I've also heard the claim that you can make a character in a TV show or movie seem smarter just by making them talk faster. And you certainly can mistake education for intelligence in casual conversation.

Along with that, IQ is a composite of a bunch of different skills, right? People within some specialized field may have a very different distribution of those skills than others--for example, I'd guess that visual artists must have some amazing sense of spacial relationships. (It would be interesting to hear from Jason on this, since intelligence testing is something he studies.)

I think a bunch of the comments back and forth with Tino are based on a terminology issue: IQ is used both as the test and as the thing (g, general intelligence) that IQ tests try to measure.

You can try to evaluate someone's intelligence in the broad sense by their work--in fact, that's what we really care about. But there's no way I can see to find out how some historical figure would have done on an IQ test. It's clear that Einstein, Darwin, Newton, Smith, etc., were all very smart guys, but we don't have an IQ test score available for any of them.

The suggestion is that it is 70% hereditable - well, if it was 10% hereditable the social Darwinists would still be correct in saying that it matters.

I'm not disputing the degree of heritability as observed by statistical correlation etc. What's unclear is the _economic_ significance of inherited variation: social Darwinists assert that it has an absolute effect on job talents, as opposed to a comparative impact through specialization effects. This claim is extremely dubious.

Also IQ is closely related to success, but not always a specific measure of success. For example a poor artist might have a high IQ and be a success at making fancy art but not making money because he never really wanted to make money.

If such a poor artist is adequately satisfying his wants, he is economically successful by definition.

You can't have it both ways: either repeated training is correlated with g or it's not.

I think you've misinterpreted something, but I'm not sure. See the papers I linked above.

The g factor highly predicts training success. The training does not increase g. Practicing the test increases an IQ score, but not the g factor extracted from the test.

IQ scores may or may not be elastic: the evidence is murky on this point.

Murky in what way?

What's the mean IQ of North Korea?

I'm saying that a relatively high mean IQ is a minimum requirement for a high level of development. I'm not saying that economic development is an inevitable consequence of high IQ. You'll be hard pressed to find me any state (outside of a few oil-rich Arab microstates like Qatar) that has a mean IQ of 80 yet is highly developed. Yes, of course, if you pursue Stalinism with any vigor, you're going to run your country into the ground economically no matter how bright your population is. I have little hope, however, that a nation like Zimbabwe will ever be South Korea economically.

I don't know what North Korea's mean IQ is. I'm not aware of any data on the matter. I'll bet it is still likely higher than the mean IQ of Mexico, however.

Group differences in IQ scores seem to be related to ethnical and cultural factors rather than simple geographical origin.

OK. But clearly ethnic groups have their origins in geographical areas. That is what I'm referring to.

For various reasons, such dependence tends to depress overall competitiveness and economic development

Again, you've proposed no plausible mechanism for how things like 'economic development' or 'labor division' are supposed to increase IQ in concrete terms. Yet, you are already appealing to other abstractions like 'lack of economic competitiveness' to attempt to dismiss seeming anomalies. At this point, your arguments in favor of 'economic development' as a cause for an increase in intelligence doesn't appear to constitute anything beyond an appeal to 'spooky economic action at a distance.' That might work in quantum physics, but it doesn't work in social sciences. How about providing some concrete examples of how economic development might increase IQ that can be examined and debated?

This is clearly untrue. For one thing, some jobs are less stimulating than others: people who expend their whole life in such menial jobs find no occasion to exert their cognitive abilities. They naturally lose the habit of such exertion, and become less intelligent as a result.

To the best of my knowledge, there is no evidence that a stimulating job environment noticeably increases IQ in younger (or older) adults. Likewise, I'm not aware of any evidence that suggests that a dull work environment substantially diminishes IQ.

I certainly don't see any evidence that work environment is likely responsible for IQ differences on the order of, say, a standard deviation such as we see between African-Americans and white Americans or between Arabs and Europeans.

The interesting question which gets back to Tyler's original post is whether the number of high-IQ people is a scarce enough resource that it's limiting growth in some or all countries.

Assume that the IQ distribution is given and we can't change it. Assume there are some jobs which require at least an IQ of C to do well. (Think of mechanics or clerks.) Let's call the portion of the population with IQ>C, P.

If your economy doesn't need at least P people in those high-IQ fields, then the supply curve for those jobs is relatively elastic--there are plenty of people smart enough to be good mechanics or clerks, say, but mostly they're working on farms or something. In this region, your economy can grow relatively quickly even if growth requires the high-IQ fields.

At some point, your economy can hit the point where further growth requires more than P fraction of the population in high-IQ jobs. At this point, the supply curve for high-IQ people becomes inelastic, and economic growth is limited by lack of smart enough people.

In reality, this is a pretty simple model. Perhaps there are good substitutes for many high-IQ occupations, though it's not clear that there are. Two incompetent mechanics are probably not able to do everything that one first-rate mechanic can do. Barely-literate clerks will probably not add much to the functioning of businesses or bureaucracies. But there surely are some substitutes--putting the rare doctors behind a wall of nurses and specialized technicians to handle the routine stuff, moving the really clever mechanics to the factory where they design the gadgets, and making the maintenance of the gadgets as simple as possible.

It seems pretty obvious that some jobs just require a lot of intelligence, and can't be substituted well at all. If some mysterious disease killed everyone in the world with an IQ over 120, we'd still have most parts of our society, but we'd probably have a heck of a time developing new drugs or space probes or keeping Moore's law going. I'm assuming here that those things are much, much harder for people with lower IQs; enough so that just throwing ten researchers at the problem that would have taken one smart one isn't a solution.

If we assume high-IQ people are a resource that limits economic growth, we probably ought to regret the large numbers of smart people going into zero-sum stuff like tax law.

At this point, the supply curve for high-IQ people becomes inelastic, and economic growth is limited by lack of smart enough people.

If this was the case, high IQ people should earn a larger compensating differential in poor countries than in rich countries, which would incent massive "brain drain" from the _developed_ to the _developing_ world! This is not what we observe, and compensating differentials are well explained by the usual factors, such as human capital accumulation, risk, and the pleasantness or difficulty of work.

I also suggest it works the following way
1) think of an area of land from history "how long has this country had a reasonable degree of civilization" (this could be a cause or an effect or both)
2) now think where are those people now? how much have they intermarried with other groups?
3) highlight those on costal areas, especially peninsulars.

just like you could use similar arguments to talk about skin colour.

Both of which seem to relate reasonably well with what we observe.

RE (1): I think about 4000 years is enough to make a very significant difference to IQ of a group if selection pressures are in the right direction. significant differences might even occur in just a couple of hundred years.


I think you need a couple other assumptions or parts of the model to know which way brain drain would go between societies. For example:

a. Country A is just richer than country B, due to more natural resources or history or whatever. They're both at the same point in the development of their economy. Country A could plausibly bid away most of Country B's smart people, even if Country B started with more smart people than Country A.

b. Country A has developed a lot further down the path toward needing smart workers than country B. This bids the wage for smart workers up in country B relative to country A.

Both of those have brain-drain in the direction of poor to rich countries, and (b) seems like it plausibly describes the world as we see it now. Alternatively, you could have something like:

c. Country A has a surplus of very smart people, enough that their economy, though very rich, isn't able to use them all up. Country B is very short on smart people, but has enough money (maybe due to natural resources) that it can bring them in from country A.

This might be a description of how the brain-drain functions in big oil-producing countries.

All this is oversimplification, and I'm not claiming any accuracy for this model. But it seems like this is what's being assumed when we talk about high IQ people as a critical resource, and it does seem plausible at first glance.

Well then, we are at a chicken-or-the-egg point. Is economic development the product of intelligence of a population or is intelligence the product of economic development? I'm much more inclined to believe the former, especially when you see persistent lags in IQ scores among not only people from the Third World but also their descendants in the First World.

Mike: how would the "persistent lags in IQ scores" you refer to among the word's poor nations clarify the chicken-or-the-egg point either way? Clearly, if intelligence in a population is furthered by economic development, then lack of economic development in a poor country would tend to calcify persistence of low IQ scores. Just the opposite would presumably occur in rich countries.

What you seem to be contending is that low IQ scores condemn an already poor nation to indefinite poverty. But this seems to be strongly contrary to common sense. There are numerous examples of nations that have begun to grow strongly after sensible economic policies are put in place. Surely if you were you correct in at least a few of these, low IQ scores amongst the populace would stop economic development in its tracks. Indeed, taking your argument to its logical conclusion, it would appear that Indians are more intelligent than Japanese, because per capita GDP is expanding more rapidly in India than in Japan.

"I referred to persistent lags in IQ scores from those who's origins trace from low-IQ regions of the world (like Africa or Latin America) versus those from high-IQ regions (like Europe or East Asia)"

Aren't you confusing 'low-IQ-regions' with 'darker skinned people regions'? I mean, the origins of Latino's in the States trace back for a considerable part to Europe (yes, Europeans did immigrate to Latin America as well) and Asia (think about the native Americans).

Peoples do not have a certain geographical origin, they tend to migrate. To list an example: both the Finnish and the Hungarians migrated to Europe from the same region (close to the Urals, I believe) in the 12th century; think about the linguistical similarity in the Finnish and Hungarian languages. However, Finland is (and has been since about 1850) economically far more succesful than Hungary. What then explains the divergence in welfare (which started before the Soviet oppression, mind you)? Is the cold climate of Finland more conducive to intelligence than the hot summers of Hungary. Or do soft variables such as culture and institutions play a bigger role than race?

Peter Scaeffer:

Asian immigrant succeeded in US because they were industrious and hard working people. However if you had tested their IQ in the 19th century (California Gold Rush, etc.) they would score pretty low.

check yourself here :)

if iq rate growth as reached it peak, many other variables r in play here. technological advances can keep gdp and living standards growing

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