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The Latest On Intelligence (danielwillingham.com)
218 points by danielford on July 17, 2012 | hide | past | web | favorite | 163 comments

"A great deal of time has been wasted in the effort of measuring the heritability of traits in the false expectation that somehow the genetic nature of psychological phenomena would be revealed."

There is a strong cultural bias among much of the research community to go out of their way to deny any genetic factors in intelligence. Perhaps this is well intentioned, but it is absurd.

I have come across very few squirrels that have mastered fire, or could be taught calculus, or even addition. I doubt that this is cultural or due to the squirrels upbringing, diet, social status, or how many books the squirrel has available to it, or the quality of it's teachers, or pathogens. Clearly then, it is possible for genetics to completely dominate other factors in determining intelligence. In the animal kingdom at large heredity/genetics account for basically all of the variation in intelligence.

The unanswered question is whether there is enough genetic diversity across the human species to cause intelligence to be significantly hereditable. The fear among scientists that try to keep the lid on this question is that the answer might be yes, and worse that such variations will correlate with geographic or national groupings. This would put a very nasty perceived scientific stamp of approval on racism (even though this would be unjustified), and could over time lead to discrimination and 'scientific racism'.

Anyway, in the end science will uncover the truth here, and in the meantime it is probably very prudent to not make any potentially inflammatory statements and to be very cautious about any studies that could fuel hate. I just find it absurd that whenever this kind of question comes up people start denying that there is any hereditary component of intelligence, and that IQ is completely meaningless, etc.

I love your example! Way out of my depth here, but i do have a question:

The squirrel obviously has a genetic trait that causes it to have a small brain. We can tell its iq just by looking at it, without considering its DNA. Would the same logic apply, when there is no visual/physical trait present?

Can one brain cell be dumber than another? Could they be wired in a less optimal way?

Genetics likely explain the difference between a retard and a functioning human, but csn they also explain the difference between an iq of 100 and an iq of 105?

When people have this debate about intelligence, the inevitable political argument is that maybe, we as a society could invest more in ourselves, our children and our neighbours children.

The relevant question, perhaps, should be: how much impact could "nurture" have? Is somebody with an iq of 120 physically limited to become smarter? Or is that person already in the range, where the genes were all good?

I dont think anybody doubts that a retarded person has a genetic disadvantage. But does the same apply to an average human being?

And if that limit exist, is it a personal limit, or one you share with most other humans on this planet?

The squirrel example is absolutely absurd - there are clear physiological, morphological differences between human beings and squirrels that influence whether or not squirrels even have the capacity to master fire, or whatever other silly comparison you choose. Furthermore, I think you will find that environmental factors plainly influence the behavior of animal populations (squirrels, chimpanzees, birds - any kingdom, genus or species you choose) far more than any particular genetic variation among them - animals of the same species without abundant resources behave quite differently from animals of the same species in an environment of abundance (one need only look at any pest species - animal or plant - to see that this is true).

There does not exist much variation across 'societies' of animals within the same species - one tribe of baboons is much like another tribe - but there exist vast gaps between societies of human beings, so far as these gaps influence the environment of individuals among populations, and entire populations as a whole.

There is no physiological model for human intelligence, and since only physiological traits are inheritable (though psychological traits may be derived from morphological differences) there is no model for genetic influence on intelligence. Since there is no model, you can only blindly test a black-box hypothesis - and the results from those tests appear to support the conclusion that there does not exist any inheritable, physiological difference that would influence intelligence, controlling for societal factors.

I don't think it's absurd, I only think initially that it was wishful thinking, now I see that it was only a poor example to a good idea that he explained later.

Yes intelligence has to do with heritability, there was initially an animal with had cognition (a word I much prefer instead of intelligence) this animal actually had descendants some of which are humans, we initially inherited this intelligence from him but also from other ancestors that developed this cognition latter as well.

You provided that we do not have a physiological model for intelligence, and I believe we will not have one for some decades at least if I'm to be optimist. That's a real large problem, another one is to relate this to genetics and environmental development, these would be a hard problem as far as I was told by some friends that are biologists.

My point regarding not having a model was to bring the genetics/environment statistics onto the same footing - the black box statistical evidence does not accept that genetics is a factor in measures of intelligence, but does accept that environmental factors such as income and health are.

I would also add, that the political agenda is not from those advancing the idea that environment influences human development, but from those that contend it is genetics.

Consider the sorts of policies someone who wanted to maximise productivity in society would develop if it was found that genetics was a greater influencing factor - why would you support development for poor populations of people if it was found that they simply don't have the same development potential? You would simply screen for the 'genius' gene and push the rest of society toward a supporting role.

In the case of the environmental view, you must now implement policies that raise the living conditions for the majority of people in society - better and more schools, better and more social programs, better opportunity - that's expensive, and there's not much money to be made.

"Consider the sorts of policies someone who wanted to maximise productivity in society would develop if it was found that genetics was a greater influencing factor..."

You have somehow completely missed and then parroted back my entire point. If it turns out that genetics plays a key role in intelligence, and therefore intelligence is hereditary, all sorts of nazi-like policies could be theoretically be falsely argued for using that as evidence. Seeing this obvious conclusion, some in the scientific community have become crusaders, trying to squash any debate or research into this topic, making it taboo.

Being taboo, or having very negative or even awful potential consequences doesn't make something true or untrue. The universe doesn't care that the consequences of some fact are moral or immoral.

I am not saying the truth is one way or the other. I am pointing out the willingness on the part of some scientists to refuse to allow investigation because of the potential consequences of knowledge of the truth.

Some? Who? I think that's an unfair accusation.

What I see sometimes in these discussions is people throwing the "hot potato" in the hands of their detractors, people that believe in the difference between groups throw the potato in the hands of the disbelievers and accuse them of being obtuse for trying not to advance an "obvious truth".

The other side just answer by accusing the others of being "racist".

The fact is the data is poor for a significant statistical analysis and for some reason this research has become heavily politicized, this in academia is a good enough reason for some people just ignore this entire field, but I never saw people trying to prevent this type of paper from being publicized or peer reviewed, last time I searched there's various being published every year.

EDIT: typos

Are you serious?

How can you say "that's an unfair accusation." and then in the next line say "The other side just answer by accusing the others of being "racist"."

I agree that there is no consensus, and no evidence that clearly helps determine the truth here. That is why I said it was an "unanswered question" in GGP.

However, we do have some ability to reason about this. Clearly genetics can play a role in intelligence. We don't know if it does between humans, but we do know that it could. Humans are very abnormally (as successful species go) genetically similar, probably because of various population bottlenecks.

So, it could go either way. It is quite obvious to me that there is a very complex interaction between genetics and environment. Some populations benefit from breast feeding, other populations do not. This is genetic. There are clearly some hereditary differences which have a measurable consequence in brain development. To what extent do these explain that one random person might be an idiot, while another might be a genius? I honestly don't know, but we shouldn't shut down debate.

Yes, I am serious, and I am not disagreeing with your point, which as I wrote about in a comment bellow was clarified in your first response to me in this thread, I actually do agree about your last three paragraphs.

It appears however that you stopped reading my comment when you saw this the second quote that you wrote, here what I wrote before:

"What I see sometimes in these discussions is people throwing the "hot potato" in the hands of their detractors, people that believe in the difference between groups throw the potato in the hands of the disbelievers and accuse them of being obtuse for trying not to advance an "obvious truth"."

This type of accusation is fairly serious in academia it's akin to say that you just invented data to fit an experiment, mind that I do not have a side in all this, I'm interested in this as a statistician, my point was to get you to give some names of the people that "have become crusaders, trying to squash any debate or research into this topic, making it taboo." No one was given and I said that say this about a group of people and not give any name is unfair.

Everyone knows about who get accused of being racist, Linda Gottfredson for example who received grants from the Pioneer Fund, I do not know about others that received grants from this Fund but I can say about Gottfredson, she came to Brazil two years ago and talked to an audience of students in Brazil, some of whom have visible African ancestry and I can attest she's not racist, she does not differentiate people because of their ancestry and do not act different answering questions of asian-brazilians, people with jewish surnames or afro-brazilians, she's honest her research and that's all.

Mind also that I have spent some time in academia and the majority of people I saw really hates politicized research, there's exceptions of course, some social scientists, historians, some legal scholars and economists, but I did not count psychologists in this group. As I said to you I asked some psychologists to provide papers some of them fairly recent.

This was my last comment in this thread it was a good discussion.

Refusal to allow investigation? According to these papers, their has been very extensive investigation with a largely null conclusion. However people continue to push the idea that intelligence is genetic.

A null result doesn't prove that intelligence is not genetic, it only says that whatever genetic components there may be have not yet been disentangled from other genetic and environmental influences.

Edit: Also, another HN commenter raised the possibility that the authors of the present study may themselves be biased (https://news.ycombinator.com/item?id=4257220).

Consider the sorts of policies someone who wanted to maximise productivity in society would develop if it was found that genetics was a greater influencing factor...

Though I do realize that some people think this way, it strikes me as wholly bizarre. If you can identify a strong genetic component of intelligence, the obvious conclusion to me is to develop genetic therapies to boost the intelligence of the entire population, with the greatest gains to be had among those who would otherwise be on the lower end of the scale.

> There is no physiological model for human intelligence...

No? I've read several. For example:

"The pronounced convolution of the human cortex may be a morphological substrate that supports some of our species’ most distinctive cognitive abilities. Therefore, individual intelligence within humans might be modulated by the degree of folding in certain cortical regions. We applied advanced methods to analyze cortical convolution at high spatial resolution and correlated those measurements with intelligence quotients. Within a large sample of healthy adult subjects (n = 65), we detected the most prominent correlations in the left medial hemisphere. More specifically, intelligence scores were positively associated with the degree of folding in the temporo-occipital lobe, particularly in the outermost section of the posterior cingulate gyrus (retrosplenial areas). Thus, this region might be an important contributor toward individual intelligence, either via modulating pathways to (pre)frontal regions or by serving as a location for the convergence of information."



When we examined the same regression model excluding ICV, some cortical measurements were associated with IQ frequently in frontal and temporal lobe. It might conclude that human intelligence is significantly correlated with the cortical complexity coming from brain size, rather than cortical shape itself. The combination of various cortical measurements explained 52.57% of IQ. The results showed that they were more useful for prediction of human intelligence than alone.


I'm not defending these particular papers. I'm just baffled at the comment that there are "no" physiological models for intelligence.

The following paper appears to directly contradict your assertion that "there does not exist any inheritable, physiological difference that would influence intelligence":

"Variation in gray matter (GM) and white matter (WM) volume of the adult human brain is primarily genetically determined. Moreover, total brain volume is positively correlated with general intelligence, and both share a common genetic origin. However, although genetic effects on morphology of specific GM areas in the brain have been studied, the heritability of focal WM is unknown. Similarly, it is unresolved whether there is a common genetic origin of focal GM and WM structures with intelligence. We explored the genetic influence on focal GM and WM densities in magnetic resonance brain images of 54 monozygotic and 58 dizygotic twin pairs and 34 of their siblings. ... These findings point to a neural network that shares a common genetic origin with human intelligence."


I'll concede this point - there exists evidence that some physiological traits may correlate with intelligence. But there does not exist a model of why or how those traits influence intelligence.

I just curious how you can support your point about squirrels, besides you falling prey of the bias of trying to advance an argument with a sole point.

For example, can these squirrels ancestors had better nutrition than the average squirrel, can we know about that just after seeing they mastering fire or wondering if they could learn calculus? I believe this type of question, the relation between nutrition and intelligence, can be answered much easily than searching for genes and looking for some desirable psychological trait in there, this can be easily tested in animals as well in a large couple of generations.

Either way I am not a biologist or even an psychologist so this is my take as a mathematician/statician. Also I'm not so confident science will ever come as close to explaining this completely.

My point is that humans are much more intelligent than squirrels. Is this because of environment? Not at all, it is because we have the genetic programming to develop huge brains. The difference in intelligence between humans and squirrels is determined almost entirely by heredity.

The reason I point this out is that it is very common to see comments about heredity not being a factor in human intelligence. It may well be that heredity does not explain differences in intelligence between two humans, or it may be that heredity almost completely explains any differences in intelligence among humans. Science will eventually figure out the truth of the matter. However, heredity plays a very dominant role in determining intelligence, the only question is whether humans are all so genetically similar with regards to intelligence that environmental factors dominate genetic factors.

EDIT: The way I phrased the first paragraph sets up a false choice. Intelligence differences among humans could be hereditary, environmental, or most likely a complex combination of the two.

In the comments of this post however I saw exactly the same point you're saying in your first paragraph, maybe in other discussion forums people denying this is more common.

You're not alone. I've always wondered, how come different dog breeds have different behavior and intelligence levels. Yet certain breeds are much smarter than others and capable of greater learning capacity. Any kind of comparison, even scientific, between human races would be seen as racist and thrown out immediately. It conjures up all sorts of negative emotions. Hitler, Nazis, Eugenics, Master Races, Holocausts.

I think deep down inside we are slaves to our genetics and many people know so and have significant evidence for it but are keeping quiet. And I don't blame them. The repercussions of telling the human race "Your success, happiness, intelligence, health, and entire life is limited by your genetics." would be horrific. Half the world would be on anti-depression medications if you told them that and proved it. No one wants to be told who they are before they're given a chance to discover themselves on their own. Also, genetics are not the end all of success. Just because someone doesn't have the genes that make them more likely to be successful doesn't mean they'll never be successful. There are other ways around. Aggression, luck, money, hard work, etc....

For instance, Ashkenazi Jews have the highest intelligence and very poor Spatial intelligence according to research. After them come north east Asians. Jews are disproportionately successful in numerous fields. 25% of Nobel prize winners are jewish and this is increasing. All of the major Hollywood studios were started by jews and are currently dominated by jews. The NYT's Joel Stein could only find 5 non-jewish executives in all of Hollywood. Most of the top writers are also jewish. Banking and finance is dominated by them as well. So is the fashion industry: Marc Jacobs, Ralph Lauren, Marc Echo, Calvin Klein, Estée Lauder, Kenneth Cole, and others are jewish. Levi's jeans as well. 2 of the internet's biggest companies, Google and Facebook were started by jews Larry Page, Sergey Brin, Mark Zuckerberg. People's refusal to acknowledge that genetics has anything to do with intelligence is exactly what has sprouted numerous conspiracy theories to try to explain why jews are so well achieved.

Also, look at men vs women. How many wars have women started compared to men? Nearly every war, genocide, and conflict has been caused entirely by men. Why is it that we never see the female versions of Hitler, Gangis Kahn, Napoleon, Stalin, etc... Because evolution has created extremely violent men (not all of us of course). Evolution wise, we're disposable. Women are not. The human race can easily be replenished with 99 women and 1 man. But not with 99 men and 1 women. And so women live much more "slow but steady" lifestyles while men are more likely to live "risky" lifestyles. Rewards are proportionate to risk. So men reap the rewards when it comes to inventions, companies, religions, nation building, etc...

> Evolution wise, we're disposable. Women are not. The human race can easily be replenished with 99 women and 1 man. But not with 99 men and 1 women

This is not how evolution works. It runs on which genes outreproduce which other genes within a species, and cares nothing for "the good of the species" or "the survival of the species". If men are more violent, it was because individually more violent males outreproduced less violent males - not because "males are disposable". (Even this is still a simplification relative to inclusive genetic fitness, but it's definitely not because "males are disposable!")


That's exactly how evolution works. Because there is an element of human choice as to which genes go on. We are a part of evolution. We choose what goes on. And we have chosen through war and death that violent men go on, and peaceful men die off. We have chosen that men are disposable, we build our armies with men, we sacrifice the men, and keep the women at home because they are the creators of humanity and men the destroyers and conquerers. Primative but it's reality.

All throughout history, wars are fought almost exclusively by men. Men killing men is alright by nature, because back since tribal times, the testosterone induced violent winner got the women and reproduced. Thus passing on his genes. The violent genes outreproduced the peaceful ones. Look at nature all around us. The violent dominate the peaceful, the aggressive dominate the passive, the intelligent dominate the dumb. The animals at the top of any foodchain are more violent, aggressive, and/or intelligent than the others beneath it.

I have a feeling we're both talking about the same thing just from a different viewpoint.

And it's a shame that postulating genetic group selection is so attractive, since ISTM that this is a very plausible case of group selection of memes about male and female tasks.

That example doesn't really apply if tribes continually split and the more violent tribes continually kill off the less violent tribes.

"Also, look at men vs women. How many wars have women started compared to men? Nearly every war, genocide, and conflict has been caused entirely by men. Why is it that we never see the female versions of Hitler, Gangis Kahn, Napoleon, Stalin, etc... Because evolution has created extremely violent men (not all of us of course)."

One thing is to say that a war is unlikely to be started by a woman (your historical observation); another thing is to say that a woman is unlikely to start a war (your claim). That's because, historically, the people in a position to start a war have mostly been men.

If W means that a given leader (i.e., someone who could have started a war if he or she wanted to) was a woman and S means that the leader started a war, by Bayes' theorem the probability of the leader having started a war, given that she was a woman, is

P(S|W) = P(W|S) P(S) / P(W)

Likewise for men (if ~ means negation):

P(S|~W) = P(~W|S) P(S) / P(~W)

You observed that P(W|S) is much smaller than P(~W|S); but to compare P(S|W) and P(S|~W) you also need to take into account how much smaller P(W) is than P(~W).

"Half the world would be on anti-depression medications if you told them that and proved it."

So at least their unhappiness isn't limited by their genes?

The horrific repercussions of loudly proclaiming the obvious are completely nullified by the near universal preference for comfortable illusions. Don't worry, be happy :)

The performance of laboratory mice in mazes varies considerably among tested populations, with some mice clearly being "smarter" than others. It's possible to train a mouse to be smarter, to learn, but the effect is only a few standard deviations from the norm at best, not orders of magnitude smarter.

Remember that genetics is, at best, all about probabilities. Just because your parents are athletic is no guarantee that you're an athlete. There's always a one in four chance that you get the worst possible pairing of genes, after all.

Intelligence is a complicated thing. A child who can remember things easily will be considered very "smart" even if they can't do much with that information, whereas one who's very clever at figuring things out will be considered "stupid" if they aren't able to memorize as well.

IQ is such an arbitrary metric that it hardly deserves scientific consideration. It completely glosses over any unusual talents someone might have.

This is an interesting result noted from the paper: "Even when improvements in IQ produced by the most effective early childhood interventions fail to persist, there can be very marked effects on academic achievement and life outcomes."

As noted by the author, this suggests that IQ only captures a portion of early childhood intervention benefits. And goes counter to those who suggest that early intervention programs serve no purpose if IQ doesn't remain high (IOW, IQ is only a portion of what constitutes success in life).

Kevin Mitchell has a very interesting take on intelligence here: http://wiringthebrain.blogspot.com/2012/07/genetics-of-stupi...

Basically he suggests thinking about the formation of intelligence to be something like trying to run an obstacle course while holding an armful of things and trying to drop as little as possible. Essentially, he is arguing that there is some optimal or standard brain and since any mutation introduced into the brain is more likely to be harmful than beneficial, more intelligent individuals are not those that inherited some specific genes for intelligence but are most likely those who avoided the most damaging non-specific mutations.

That’s [runaway selection of intelligence boosting genes] all nice, though admittedly speculative, but those mutations are the ones that we would expect to not vary in human populations – they would now be fixed. In particular, there is little reason to expect that there would exist new mutations in such genes, present in some but not all humans, which act to further increase intelligence.

To test this he suggests using symmetry as a proxy for robustness in the individual. This fits well with the fact that all attempts thus far to find a common genetic basis for intelligence have failed, the correlation between intelligence and immune function, ideas that intelligence was indirectly selected when optimizing for healthy mates and findings that Nootropic like substances tend to have the least effect on already intelligent minds. In the last case, it is interesting to note nootropics should then be viewed not cheating but more leveling of the playing field. Taking this further, genetics are not the only obstacle course - there is still variation in the womb environment and early childhood. The interplay of genes and the stability of process in the growing brain; affected by a lack of stimulation, poor nutrition and a stressful womb environ would likely have more impactful effects on intelligence than pure genetics.

Am I the only one who reads these kinds reports and has that impression that today's psychology and biology is less than 0.1% of the way to provide a useful model for intelligence? The best measurement of intelligence that we have today (IQ tests) seem completely worthless for practical purpose compared to what we actually need to know to build solutions on. IQ tests are still too bad to measure actual "intelligence", as defined by our colloquial meaning and practical real-world potential. (as opposed to the official technical definition) Being able to measure people's intelligence would be extremely useful. IQ test results, not so much.

New findings about the impact of genetic vs environmental influences on IQ tests. Is about as useful finding new evidence about genetic vs environmental influences on people's ability to pass a "lick your elbow" test. Why should I care? It sure is interesting, and hey, anything "for science!". But, meh...

How do you explain the fact that when the law allows, companies all over the world give IQ tests to prospective employees? And that studies have shown that IQ is one of the best predictors of job performance?

Your first point would only elucidate a common misconception that IQ tests adequately measure intelligence. As to your second point, what studies are these? (I'd actually be interested)

I personally believe IQ is a fairly good predictor of intelligence the way people in (at least American) society think about it. This study attempts to prove that high IQ is good for most jobs. What it doesn’t prove is the high end of the spectrum where someone of 120 IQ compares with someone of 140IQ in extremely high level jobs. My experience is that creativity trumps IQ in most cases where people are considered generally intelligent. The people that really are viewed as most successful typically have a high or very high IQ, but are always very creative.

But isn't it fascinating how much we can learn about intelligence even if we rely on crappy metrics like IQ tests?

Just like you can learn a lot about music without having a formal definition of what "good" music is.

IQ is one of those “look for the keys under the streetlight” things. It's for people who really care about intelligence being something measurable as a decimal number. In every study that isn't a meta-study like this one, the tasks that were measured are available and will tell more of the story.

Our minds are modular, studies measuring ability at precise tasks can improve our understanding of it. I wish people didn't try to make silly sweeping statements on nature vs nurture something that science has to care about.

The only justification for this paper is that it is debunking a book that was originally pseudoscience, but the whole discussion that followed that book is flawed for letting that book set the framing that intelligence boils down to one number.

"The extent to which genes matter to intelligence varies by social class (genetic inheritance matters more if you're wealthy, less if you're poor)."

It's always seemed obvious to me that this ought to be true - that is that environment will matter more if you have greater differences in environment. In the extreme case if you feed kid A and don't feed kid B, then kid A will end up with an infinitely greater IQ than kid B.

The point is actually more subtle than that though. What they're saying is that holding social class constant, genetic difference is more important for the wealthy than the poor.

For example, kid A and kid B are both wealthy and have significant genetic differences related to factors affecting intelligence. In this case kid A and kid B are likely to have significantly different intelligence from each other.

Conversely, kids C and D are both poor and have similar genetic differences to A and B. They will show much less difference in intelligence from each other.

That fact is certainly not obvious, but it is fascinating.

Right. The implication, in my mind at least, is that fighting poverty should be one of the key goals of society. Being in poverty effectively hides gifts as poverty will dominate "natural" ability.

Perhaps related, "Preschool: The Best Job-Training Program": http://www.npr.org/blogs/money/2011/08/12/139583385/preschoo...

Reply to scott_s: In that article, note that the study addressed the effect of pre-school on strongly disadvantaged children: "Only disadvantaged children living in adverse circumstances who had low IQ scores and a low index of family socioeconomic status were eligible to participate in the Perry program."

Right, it's not an experiment for the conditions under discussion. It is, however, an experiment which demonstrates the importance of early childhood environment.

Or at least we should be pushing micro-nutrient supplements. And encouraging school lunch programs.

That's a pretty huge assumption, that micro-nutrients are a significant part of any difference.

You've assumed, first, that it's poverty that causes the lowered IQ, rather than that both poverty and lower-IQ are both effects of a common cause.

Second, even if there really is a causal chain, why in the world would you assume that the difference is related to nutrition? Why not, for example, cultural differences in the way that poor parents interact with children compared with the way that non-poor parents do?

If poverty doesn't cause lowered IQ how would explain children adopted into non-improrished households having higher IQs? I don't have good evidence that nutrition is the primary factor here, but there is a lot of research saying that nutrition is important with respect to IQ.

I come from a reasonably well off family. Ma parents did not think they could have children, so they adopted a boy and a girl. Then I came along.

I look like my parents, think like my parents and in many ways, behave like my parents. However, I have outright rejected their religious beliefs (so there are some differences, but these could be the lack on indoctrination or maybe circumstance. My sister met her biological mother for the first time when my sister was 23. They both smoked, wore similar clothes, had similar musical tastes, similar social past times - in just about every way, they were very alike. More importantly, my sister is almost nothing like me, despite the very similar nurture/environment. My brother was a very similar story, always in trouble with the law. My parents had a strict policy, if one got something, we all got it. However, they recognized strengths and nurtured those. So we have a family whose genetics have driven our looks, personalities, interests, careers (if you consider crime a career for my brother) and in my view, intelligence was also varied. Adoption did not influence my siblings as far as I can see (by comparison with biological parents). All I have ever seen in my life in nature, nature, nature. To add to this, we all have kids, and guess what? Our kids are all similar to their parents too. Looks/behavior and again, I'd argue intelligence. Having said all of that, we are all intelligent in our own ways. As an example, my brother is very street wise- he's a great manipulator, a player. He can handle himself in many situations. I fundamentally reject any urgument that nature plays no part in any aspect of what makes a person, including intelligence. Do you think the similarities end with looks?

Post hoc ergo propter hoc is one of the classic logical fallacies[1]. You persist in the assumption that poverty causes lower IQ, rather than the possibility that both poverty and lower IQ are correlated because they share a common cause.

[1] See http://www.skepdic.com/posthoc.html

The way you do a controlled experiment in science is that you have a number of subjects, you subject only some of them to some new condition, and then you look for statistically significant differences between the group subject to the condition and the one that wasn't.

That was what happened in the study I mentioned.

Now, you can say that this wasn't absolute proof and you'd be right, because science doesn't provide any absolute proof. But if you're going to throw out this evidence you're going to have to throw out the rest of modern medicine too.

The problem is that often there will be several factors linked together. Richer households will have better nutrition, but they'll also behave differently, have more books, associate more with other richer families, etc. It's really hard to unlink these factors, even when trying to control studies statistically.

Nutrition is a really low hanging fruit, and you have to be pretty poor for it to have any effect.

you can say that this wasn't absolute proof and you'd be right, ... But if you're going to throw out this evidence you're going to have to throw out the rest of modern medicine too.

No, what needs to be thrown out is armchair scientists who don't properly understand the scientific method. Just because you've shown a statistically-significant correlation between two phenomenon, there really is very little reason to expect that shoring up one of those phenomenon will actually have an effect on the other.

Let's look at the question at hand, the correlation between (low) IQ and childhood poverty. Observing that the poor are more likely to be undernourished and at the same time, children in poverty show fewer signs of inherited high intelligence, there is very little (one might even say zero) reason to believe that giving poor kids food will improve their intelligence.

People seem to nod their heads and say "yeah, whatever" when challenged on the difference between causation and correlation, but in fact there's a world of difference.

Here's an alternative speculation about the real causation of the observation. Being a single-parent household causes poverty because a smaller income must be spread across the same fixed expenses (rent, etc.) and nearly the same variable expenses (say, 3/4 the food, medical care, etc.), and thus the money "runs out" sooner. Being a single-parent household also causes lower IQ, because there is less parental involvement available to the child (helping with homework and the like), because a single parent must be consuming at least as much time working, more (per family member) doing necessary household chores, and thus less remains for the kid.

Through this chain of causation, throwing food at the problem may fix the malnutrition, but that's not the identified cause of the lower IQ, so if our goal is to improve IQs, then the investment was entirely wasted. We've still got as many single-parent households who can't invest as much time interacting with the child, and since the actual cause is still out there, there will be just as many lower-IQ kids. Your un-scientific jump to conclusions about the causation has wasted what you've invested to fix it, and worse, because you believed you were fixing it, you've actually blocked more legitimate efforts to fix the real cause.

Really: seeing a correlation is no reason to believe that there's causation in effect. This is true in philosophy, but just as true in science!

They do share a common cause: a lack of money. Increasing guaranteed income improves those measured outcomes: http://www.mitpressjournals.org/doi/abs/10.1162/003465399558... That is, by giving their parents money you improve children's cognitive performance. I'm not sure what more causal evidence you are looking for. Also see https://files.nyu.edu/mw109/public/loken_mogstad_wiswall_fam... for the statistics involves.

Poor isn't a culture.

Poor isn't a single culture, but it's quite likely that poverty has certain consistent cultural effects which could contribute to lower IQ.

Actually it kind of is.

Not that that isn't a great thing to do, but how does that help anyone overcome the limits on opportunity that poverty places on them?

Malnutrition can be one such limit of opportunity, if it harms development in childhood. It's also one of the easiest things to fix; giving children nutritional supplements and subsidized school lunches is pretty cheap and straightforward, compared to just about any other method of ameliorating poverty.

Ah, OK, I see what you're saying.

How do you define "poverty"? Most impoverished Americans have TVs and microwaves.

>Most impoverished Americans have TVs and microwaves.

What's your point? Ownership of an arbitrary appliance doesn't mean you're able to put food on the table or afford tuition for your children. You don't need to eat a TV every night to survive nor can you fill up your gas tank on microwaves. Besides, in the developed world, TVs and microwaves are a dime a dozen and are regularly discarded because their abundance makes them worth so little.


He asked a good question. To what level does the bar need to rise to eliminate poverty as something that holds someone back? Is easy access to food and education that level?

My gut feeling that wealth disparity is a bigger issue than absolute wealth. If the poor lived in mansions and drove Ferraris, but the rich owned entire islands and private rocket ships that travel to Mars, the poor people still wouldn't have access to what the wealthier people have, still setting them back from achieving their true potential.

>If the poor lived in mansions and drove Ferraris, but the rich owned entire islands and private rocket ships that travel to Mars, the poor people still wouldn't have access to what the wealthier people have, still setting them back from achieving their true potential.

It's not about absolute material equity, it's about comfortably meeting one's needs such that second order concerns (like studying or tinkering with a mobile SDK) become viable pursuits. Living in a mansion means you can likely afford food, rent, transportation, insurance, healthcare, tuition, and all the other expenses that leave the poor with little room for "achieving true potential".

Anecdotal evidence: When I was the poorest I have ever been I had a TV and microwave.

My microwave came with my apartment and the TV was free because a neighbor had just got a new one. I still had to live off ramen.

What's your point? Ownership of an arbitrary appliance doesn't mean you're able to put food on the table...

Most impoverished Americans overeat. The average poor American is borderline obese.


It's still cheaper (or at least perceived as being cheaper due to clever marketing by food companies) to gorge oneself on junk calories than to half-starve on fresh, healthy food.

A microwave costs a couple of days of labor in the U.S. and then lasts for a couple of years. It's a pretty basic item these days.

For evaluating the impact on life outcomes, why not define poverty as the state where (lack of) financial resources frequently limit the choices available to an individual?

I don't think poverty is fully explained by external factors, but I think that unexpected events do tend to have a larger impact on people with limited resources, often exacerbating their problems.

Your reply captures the sentiment very well - ownership of a microwave really isn't a good indicator of poverty. It IS a good indicator of the kind of systemic poverty that exists. Simply by luck of being born within the US, I'm privileged with higher wages which gives me the opportunity to purchase one, and easier access to buy such appliances. I can purchase one at any time (24/7) for an hour's wage, if not less.

For evaluating the impact on life outcomes, why not define poverty as the state where (lack of) financial resources frequently limit the choices available to an individual?

I like your definition for poverty. I'm well acquainted with our (US) social services that provide food, shelter, clothing, transportation, basic phone and internet service, and education funding to any parent, woman, or child, and some single men. By this definition, I'm led to believe that poverty doesn't exist within the US, even though myself and most of my friends and family fall below the "poverty line".

Feel free to ignore me, i've got nothing to hold up as any kind of authority on the subject, but i'm curious if my thinking is irrational.

I'd thought genetics only mattered for the elite. I'd always used the olympics as an example of this. Take a few hundred people with the best drive, nutrition, and training from all over the world. What's left to set them apart? genetics.

If you're not elite, who cares? you can just eat better, work harder, train smarter, whatever.

To put it another way, how often is genetics the limiting factor? If you've really done all you can do to improve, then you can blame stuff you can't actually do anything about, like genetics.

The mental model I'm using here is that IQ is the result of something like (Genetic g) * diminishing_returns(nutrition). And that nutrition is something like K1*(social_factor) + K2 + noise(). So noise is going to result in smaller deviations when the social_factor is higher.

Before reading that website I would have expected that variations in the first term for nutrition would be small compared to the second term, so I wouldn't have necessarily expected this to show up between affluent and poor kids in the US. But between affluent kids in the US and kids from sub-Saharan Africa I certainly would have.

EDIT: In fact, I would have guessed the working-class/middle-class IQ differences were an order of magnitude lower.

I think it implies that if you're wealthy, you are able to fully meet your intellectual potential, thus the greater spread for wealthy children.

And conversely, if you are poor, you are hard pressed to gather the resources needed to improve your cognitive faculties, and may appear indistinguishable from someone who doesn't even want to gather intellectually enriching resources.

Be careful about coming up with an explanation for a result, and then thinking it is obvious: http://lesswrong.com/lw/im/hindsight_devalues_science/

Scott, that is a correct point, but that important warning works both ways in many controversies about scientific findings on issues that people think they know about from personal experience. Human intelligence research, when discussed among laymen, is particularly an area in which people make strong claims on the basis of "it's obvious that" or "everyone knows" when the strong claims are neither obvious nor things that everyone knows.

The way to reality-check someone's impression of how the world works is to gather more data. In human intelligence research, James R. Flynn (a co-author of the paper under review here) has enjoyed particular success in making claims that run against the "everyone knows" bias of individual differences psychologists, and then being backed up by other psychologistics (and getting published in the top journals in psychology) when data are found to back him up.

Here is what Arthur Jensen said about Flynn quite a few years ago, and he hasn't retracted this statment: "Now and then I am asked . . . who, in my opinion, are the most respectable critics of my position on the race-IQ issue? The name James R. Flynn is by far the first that comes to mind." Modgil, Sohan & Modgil, Celia (Eds.) (1987) Arthur Jensen: Concensus and Controversy New York: Falmer. Here's what Charles Murray (all right, neither a psychologist nor a geneticist, but, as the review points out, an author who has written about these issues) says in his back cover blurb for Flynn's book What Is Intelligence?: "This book is a gold mine of pointers to interesting work, much of which was new to me. All of us who wrestle with the extraordinarily difficult questions about intelligence that Flynn discusses are in his debt." As N. J. Mackintosh writes about the data Flynn found in his book IQ and Human Intelligence: "the data are surprising, demolish some long-cherished beliefs, and raise a number of other interesting issues along the way." Flynn has earned the respect and praise of any honest researcher who takes time to read the primary source literature. Robert Sternberg, Ian Deary, Stephen Pinker, Stephen Ceci, Sir Michael Rutter, and plenty of other eminent psychologists recommend Flynn's research.

A mental test, perhaps, to determine if something truly is "obvious": if the fact is reversed, and you can come up with a reasonable sounding explanation for the reverse, then the original fact is not obvious.

In other words, only consider something obvious if you could not explain the opposite.

Another good rule of thumb is that if you're ever in a position where you feel the need to assert that something is "obvious", it probably isn't.

All too often people try to end a debate by asserting that some point (from which their position inevitably follows) is "obvious". If it were obvious, they likely wouldn't be having the debate in the first place. It's much more likely that someone disagrees with the foundation of an argument than that they agree with the premises but are too stupid to see their consequences.

A mental test, perhaps, to determine if something truly is "obvious": if the fact is reversed, and you can come up with a reasonable sounding explanation for the reverse, then the original fact is not obvious.

This experiment has been tried, by a scientist who presented the exact opposite of various findings to undergraduates, who were readily able to invent rationales for the counterfactual statements, as reported in "A Sociologist’s Apology" (as posted on the website for the book Everything Is Obvious: *Once You Know the Answer).


Eliezer Yudkowsky cites the same experiment in the essay I linked, which was my motivation for bringing it up. I'm not proposing an experiment, however, but a mental tool for people who are trying to be honestly rational. And my motivation for why this tool will work is that experiment.

Of course, using this mental tool requires that you are honest with yourself when you try to explain the counterfactual statement.

Not sure if you were trying to imply something different, but that result would suggest that the students don't have adequate basis for claiming that things in those fields are "obvious" (or of their own confidence levels), not that the community of scientists in those fields lack adequate epistemic basis.

I'm sorry if I ended implying I was using hindsight, I meant to claim that this was obvious to me in advance. I'm pretty sure its even in my comment history where we were discussing someone's claim that IQ wasn't a real thing even though it was a heritable thing, and I asserted that "there isn't just one heritability of IQ" or words very close to that.

At the risk of being rude: I don't believe you. It's just too hard for us to disassociate current knowledge from our intuition. I do believe that your prior statements are in support of the one in question, but I do not believe that those statements make this one obvious. (That is, I don't believe you when you say your prior statements would clearly imply the current one.)

It's reasonable for you not to believe me, which is why I dug up the link: http://news.ycombinator.com/item?id=2210604

Except I think the author would point out that there isn't just _one_ heritability for things like height because height would be much more heritable in environments where everyone has adequate nutrition as opposed to in environments where nutrition was a matter of luck, for instance.

Rereading the blog post I was referring to, I'm not as certain that the author would actually agree with me here, but at the time I thought the point was so obvious that anybody who thought about it would agree.

Very interesting point, but I'd argue it has different implications to different fields of study. In physics, for example, if ten years from now it turned out that the existence of Higgs boson, in hindsight, was an "obvious" part of a wonderfully intuitive theory, most physicists would be elated and consider it a proof of the strength of their theory. Arguably a different story in social science.

I'm not sure that analogy works because the Higgs boson was not a surprise. It was predicted by the Standard Model of particle physics. I also worry that you're abusing the word "obvious."

This article is very hard to digest because of the writers switching of "intelligence" and "IQ". Intelligence =/= IQ. IQ is a score on a test, and intelligence is a vague set of mental skills and processes to solve problems of varying degrees and subjects. To say that they are equal is like saying that athleticism is equal to the number of pounds you can bench.

If the writer is talking about IQ, then these investigations aren't interesting, as IQ is a very small subset of intelligence (the ability to solve those types of problems on a test, which you can easily train for). If the writer is talking about general intelligence, then the writer really shouldn't be mentioning IQ at all, as it is notorious for being confused as actual intelligence.

Without a consistent, objective definition, "intelligence" makes no sense. If you would like to dissociate IQ and intelligence, go ahead, but IQ is a metric that has correlations with many other factors (test performance, income, a whole slew of things really).

Correlations mean almost nothing. Just going off your list:

-IQ:Test Performance - Of course. IQ is a grade off of a test. It correlates with itself. If you mean tests such as the SAT or tests in a school, then yes, IQ does help somewhat with that, as it was designed to (the first IQ test, created by Alfred Binet, was designed to find students who would not do well in a regular school environment). However, do high test scores mean high intelligence? Not necessarily, as most test scores can be improved drastically with a class focusing only on the test, showing different tricks that the test maker's use. Same with IQ tests.

-IQ:Income - Income (generally) means higher education level, and modern education teaches the general forms of questions asked on tests, such as the IQ tests. Education trains the mind to think along the lines of what the IQ test uses to grade performance. Also, spoken another way, if IQ (which is "intelligence") correlate with income, then one can say that income correlates with IQ ("intelligence"). If this correlation is weak, then it is meaningless. If it is strong, then that is a very strong evidence for eliminating the lower classes to raise the "intelligence" level of a nation.

Most other factors follow along these lines. The problem with correlation is that it is not, in any way, a suggestion or a proof of causation. There can be infinitely many other factors that can be influencing the two.

I do agree that without a consistent, objective definition, one cannot possibly study intelligence. However, IQ is not a good definition of intelligence. At best, it tests "academic" intelligence, and at worst, it tests test-taking ability.

Taking from Wikipedia:

>"Individuals differ from one another in their ability to understand complex ideas, to adapt effectively to the environment, to learn from experience, to engage in various forms of reasoning, to overcome obstacles by taking thought. Although these individual differences can be substantial, they are never entirely consistent: a given person's intellectual performance will vary on different occasions, in different domains, as judged by different criteria. Concepts of "intelligence" are attempts to clarify and organize this complex set of phenomena. Although considerable clarity has been achieved in some areas, no such conceptualization has yet answered all the important questions, and none commands universal assent. Indeed, when two dozen prominent theorists were recently asked to define intelligence, they gave two dozen, somewhat different, definitions." -APA report quoted in the article.

The examples you gave exactly match my intentions. I'm not sure where we are disagreeing, unless you are interpreting the phrases "intelligence" and "intelligence quotient" as more exclusive than most people. If that is the case, give me your definition of "intelligence", and we'll see where we go from there.

I'm saying that interpreting IQ as intelligence is extremely narrow-minded and misleading to the general public. There is absolutely no evidence that IQ is a decent measure of intelligence. My point is that intelligence is a much broader subject than simple IQ, and using IQ as a measure of intelligence will produce both false positives (by training for the exam) and false negatives (by not targeting other areas of intelligence than the specific area used in some types of academia).

I am not saying that there is a specific definition of intelligence that is good. I am saying that IQ as intelligence is not good. I wouldn't have a problem if people did use the terms "intelligence" and "IQ" so interchangeably. If the linked article talked only about IQ, then I would have no problem, but the article specifically talks about intelligence, and then uses studies on IQ to try to makes points about intelligence.

By the way, if you are looking for a better theory of intelligence (which is beside my point), then you should look at Cattell-Horn-Carroll Theory (http://en.wikipedia.org/wiki/Cattell-Horn-Carroll_theory) as an example.

> There is absolutely no evidence that IQ is a decent measure of intelligence.

Other than it correlates with all sorts of positive life factors, you mean? Like health, earning power and lack of a criminal record?

Nobody is saying that IQ is intelligence, including the author of the article. But it's a fairly large component of it.

Any argument containing the word "intelligence" at all is hard to digest, because the idea is so totally vague as to be useless.

Unless you operationalize it as something measurable. Such as IQ.

There is no point talking about intelligence in the abstract unless you can actually say what you actually mean in such a way that 30 readers won't develop 30 completely different interpretations of what it is you are saying.

What is "actual intelligence"? And let's not, like Humpty Dumpty, say that words mean just what we choose them to mean.

Daniel Willingham knows a lot about this subject (I took into to cognition with him a couple of years ago). Of course in the linked article he is just paraphrasing other people's work, but he does a lot of similar stuff himself especially on developmental neuroscience in learning and reasoning. It is very interesting to be taught by someone who knows a ton about learning and how to learn from the neurological point of view.

I didn't read the entire paper, but to someone who did, how much of a link is there between genetics and IQ? I know this isn't a popular subject, but if I remember correctly I believe that Ashkenazi Jews constitute 3% of the population yet have won 27% of the Nobel prizes in science.

I would think that much like how different types of people from different regions have differing athletic capabilities, there would also be differences in mental facilities as well -- some better at music, some better at math, etc. Thoughts?

It says a lot about it. For instance:

"She examined the IQs of Black and mixed- race children averaging 8.5 years of age who were adopted by middle-class families who were either Black or White. The children who were of half-European origin had virtually the same average IQ as the children who were of exclusively Black origin. Hence European genes were of no advantage to this group of 'Blacks.' Children (both Black and mixed-race) adopted by White families had IQs 13 points higher on average than those adopted by Black families, indicating that there were marked differences in the environments of Black and White families relevant to socialization for IQ; indeed, the differences were large enough to account for virtually the entire Black–White gap in IQ at the time of the study."

It says less about Jews in particular, which I'd guess is because of a lack of data. There's not a heck of a lot of Jews up for adoption, relative to blacks. But it does note:

"It is important to note that even at the highest estimates we have of Jewish IQ, Jewish accomplishment exceeds what would be predicted on the basis of IQ alone. Nisbett (2009) has argued that the numbers of Jewish Ivy Leaguers, professors at elite colleges, Supreme Court clerks, and Nobel Prize winners are greater than one would expect even if average Jewish IQ were 115. He has also noted that remarkable as the superior achievement of Jews is, the achievement difference between Jews and non-Jews is far less extreme than differences between groups in many other comparisons that cannot be explained on purely genetic grounds, such as the achievements of the Italians versus the English in the 15th century, of the English versus the Italians after the 18th century, of Arabs versus Europeans in the 8th century, of Europeans versus Arabs after the 14th century, and of New Englanders versus Southerners throughout American history."

While it is certainly plausible that there is some big genetic influence on intelligence due to ethnicity, like there is in athletics, we have yet to find convincing evidence of it.

People always ask this incorrectly. The real question is "To what degree does genetics determine the difference of average IQs between groups." The link between genetics and IQ is near 100% in an absolute sense, as tapeworms and dogs generally will score a 0 on any test.

Even the worst possible environment...say, repeated concussions to the head via a hammer, will still result in a human scoring far above any non-human.

Even the worst possible environment...say, repeated concussions to the head via a hammer, will still result in a human scoring far above any non-human.

I'm pretty sure you're wrong. I think research suggests that dolphins, parrots, bonobos and some other animals have tested higher than humans.

At standard IQ tests? Surely the creature doing a a standard IQ test needs at the very least opposable thumbs?

There will of course be exceptions, but a brain damaged but somewhat functioning human will always score better than a non-human at human-designed intelligence tests.

The argument isn't that a dolphin or bonobo isn't potentially smarter than a brain damaged human, but that by designing our tests for human use we are explicitly excluding non humans.

What are you trying to point out? That IQ tests as they are written for humans are biased in favor of humans?

Intelligence between humans and animals can (or could) be compared, but--like when testing between human populations--you wouldn't use a test that is so heavily biased against one of the groups that they can't even attempt it.

Both scientific and athletic achievements have an alternative explanation: culture. If there was a good sample of adopted children from a group with such achievements, one could examine these hypotheses in more detail.

That's an incredible statistic. If the cause is cultural then it's a wonder there isn't a plethora of books advising on how to raise children the Ashkenazi way. Are there any such books?

Typical HN racism and misogyny aside, why not go to the top of the intellectual world and listen to Chomsky and Einstein? There's no end of opinions from them. Chomsky in particular answers emails quickly. So no need to ape some culture's forms, but rather ask their most successful members.

The problem is, their answers don't please many who'd ask such questions. Einstein claimed:

"This crippling of individuals I consider the worst evil of capitalism. Our whole educational system suffers from this evil. An exaggerated competitive attitude is inculcated into the student, who is trained to worship acquisitive success as a preparation for his future career."

Or take Chomsky:

"A lot of the educational system is designed for that, if you think about it, it's designed for obedience and passivity. From childhood, a lot of it is designed to prevent people from being independent and creative. If you're independent-minded in school, you're probably going to get into trouble very early on. That's not the trait that's being preferred or cultivated. When people live through all this stuff, plus corporate propaganda, plus television, plus the press and the whole mass, the deluge of ideological distortion that goes on, they ask questions that from another point of view are completely reasonable...."

So let's turn the question around (because it's not about Jews being the Master Race or being culturally superior to say Africans): how do we triumph over dominant institutions which are out to turn us into idiots?

We don't want to know what Chomsky or Einstein thought about the educational system, that's irrelevant. What we really want to know is how their parents treated them. Actually, we want something more general -- commonalities in Jewish upbringing, especially of those who went on to be successful.

I'm not sure who "we" are, and why "we don't want to know" things despite wanting to be smarter. In any case, Chomsky certainly wasn't secretive about his education and parenting. Did you look it up?

"My father was, professionally, a Hebrew scholar, and worked with Hebrew grammar. And my mother was a Hebrew teacher. My father sort of ran the Hebrew school system in the city of Philadelphia, and my mother taught in it. He taught in Hebrew College later. There's a Graduate University of Jewish Studies, Dropsie College, which he taught in."

"Actually, I happen to have been very lucky myself and gone to an experimental-progresive Deweyite school, from about the time I was age one-and-a-half to twelve [John Dewey was an American philosopher and educational reformer]. And there it was done routinely: children were encouraged to challenge everything, and you sort of worked on your own, you were supposed to think things through for yourself -- it was a real experience. And it was quite a striking change when it ended and I had to go to the city high school, which was the pride of the city school system. It was the school for academically-oriented kids in Philadelphia -- and it was the dumbest, most ridiculous place I've ever been, it was like falling into a black hole or something. For one thing, it was extremely competitive -- because that's one of the best ways of controlling people. So everybody was ranked, and you always knew exactly where you were: are you third in the class, or maybe did you move down to fourth? All this stuff is put into people's heads in various ways in the schools -- that you've got to beat down the person next to you, and just look out for yourself."

Ok, raised by teachers/scholars who even ran a school system, and went to a school which cultivated critical thinking. Surprising that he turned out to be such a successful academic...

No need to turn to racist theories, or cultural mysticism. Answers are quite simple, but not everyone wants to hear them.

But that's the cargo cult way. You end up replicating a lot of unrelated random things and may still lose the essense of it.

Sort of. In achievement-obsessed South Korea, there's wide reverence for judaism and study of the Talmud, despite the country historically being very non-jewish. http://www.thejc.com/lifestyle/lifestyle-features/48771/why-...

While not completely the same or as limited in scope, I have come across this a number of times. http://en.wikipedia.org/wiki/Minnesota_Transracial_Adoption_...

These kind of studies have been done, and it is my recollection that genetics still appear to have a significant impact. Of course, people can still argue that various sociological effects can explain most of this, like lowered expectations for certain races, etc.

Would love to see some cites.

Certainly culture plays a role, but it's hard to argue that the reason a non-representative proportion of olympic runners are black is due to culture. http://static.guim.co.uk/sys-images/Sport/Pix/pictures/2008/... really demonstrates this fact.

What that picture doesn't show, though, is that there are a lot of almost-world-class sprinters who are european, asian or of other ethnicities. The edge that being of a certain ethnic background gives you in sprinting is only really important at the very top of the competition. I'd imagine that for the majority of people, training and dedication make up a far larger component of their success or failure at sprinting.

Interestingly, in the article it indicated that genetics appeared to play a bigger role in the intelligence of wealthy people. I'd imagine this is a similar situation. Genetics may give you a slight edge at the very top of academia, but otherwise education is the key.

Education is the low hanging fruit in increasing overall intelligence.

Right, but my question is for only the genetic effects (even with adopted children of different cultures there will be other differences that are not genetic). It would be difficult to determine, but there are enough statistical techniques that one could get a good idea. Surely different races can't have identical distributions of various "skills" -- the only question is how much they are offset from each other.

>but if I remember correctly I believe that Ashkenazi Jews constitute 3% of the population yet have won 27% of the Nobel prizes in science.

Can we get a citation on this?

"Nobel Prizes have been awarded to over 800 individuals, of whom at least 20% were Jews, although Jews comprise only 0.2% of the world's population.": http://en.wikipedia.org/wiki/List_of_Jewish_Nobel_laureates

Although this need not be explained by genetics. It could just as easily be explained by culture.

It would be strange to assume uncritically that Nobel prizes were given out in a way which was completely unbiased. For example, it is at least highly plausible that there are biases on the basis of nationality, connections, school background and other things which have nothing to do with merit, ethnicity OR culture as such. So it seems strange to me to suggest that it must be some aspect of Jewishness that determines this difference.

I'm actually not assuming that - I tried to write something to that effect, but I wasn't pleased with what I wrote. Take my comment with the pre-condition that if we're going to assume it has something to do with Jews themselves, it need not be attributed to genetics.

Absolutely understood, and I apologize if that came across as a sharp rebuttal.


Oh, I don't think anyone doubts that. The question we are discussing is: to what extent does their innate genetics (categories of similar DNA, if you prefer) influence their intelligence?

Page 3 of Natural History of Ashkenazi Intelligence: "During the 20th century, they made up about 3% of the US population but won 27% of the US Nobel science prizes and 25% of the ACM Turing awards. They account for more than half of world chess champions."


What's important to note here is that, assuming normal distribution, group differences can account for large differences in the number of individuals at the very top (and bottom). If a group A has a mean IQ of 100 and group B has a mean IQ of 110, group B will have four times more individuals with IQ over 130 than group A.

I would upvote this twice if I could. I have read the underlying paper

Nisbett, R. E., Aronson, J., Blair, C., Dickens, W., Flynn, J., Halpern, D. F., & Turkheimer, E. (2012, January 2). Intelligence: New Findings and Theoretical Developments. American Psychologist, 67, 130-159.


Daniel Willingham reviews in the submitted post, and the paper is a joint review article on the last decade and a half of research on human intelligence by an all-star group of researchers.

After edit: I see other comments are asking about what the research shows about genetic influences on IQ and environmental influences on IQ. Here is some FAQ information on that, originally part of another comment I posed here on HN:

The researchers in the Behavior Genetics Association are making increasingly cautious statements about genetic influence on human behavioral traits as more data are amassed. Here are some of the latest statements by some of the leading researchers.

Turkheimer, E. (2012). Genome wide association studies of behavior are social science. In K. S. Plaisance & T.A.C. Reydon (Eds.) Philosophy of Behavioral Biology (pp. 43-64). New York, NY: Springer.


"If the history of empirical psychology has taught researchers anything, it is that correlations between causally distant variables cannot be counted on to lead to coherent etiological models."

Johnson, W., Turkheimer, E., Gottesman, I. I., & Bouchard, T. J. (2009). Beyond heritability: Twin studies in behavioral research. Current Directions in Psychological Science, 18, 217-220. [I am personally acquainted with three of the four co-authors of this paper, one of whom regularly exchanges links with me by email.]


"Moreover, even highly heritable traits can be strongly manipulated by the environment, so heritability has little if anything to do with controllability. For example, height is on the order of 90% heritable, yet North and South Koreans, who come from the same genetic background, presently differ in average height by a full 6 inches (Pak, 2004; Schwekendiek, 2008)."

Turkheimer, E. (2008, Spring). A better way to use twins for developmental research. LIFE Newsletter, 2, 1-5.


"Unfortunately, that fundamental intuition is wrong. Heritability isn’t an index of how genetic a trait is. A great deal of time has been wasted in the effort of measuring the heritability of traits in the false expectation that somehow the genetic nature of psychological phenomena would be revealed. There are many reasons for making this strong statement, but the most important of them harkens back to the description of heritability as an effect size."

My problem with upvoting is that I have read the underlying paper, and I'm not impressed at all. This paper takes a hugely nurturist approach, and at parts verges on dishonesty.

I consider myself - if not an expert, at least very well informed - on the topic of dual n-back and I was flabbergasted when I read pg11 of the PDF. There is not a single mention of the many failures to replicate, methodological critiques, or skeptical meta-analyses about n-back. Some of that can be explained by the January 2012 date, but only a very some of it because a lot of that long predates 2012 or 2011, and it can't be explained by the people involved being ignorant because they thank Jaeggi, Duckworth, Jonides, and Sternberg - who certainly would know!

Someone reading this paper would come away with a very different understanding and expectation for dual n-back training than someone reading my http://www.gwern.net/DNB%20FAQ . So all I can think is, "if this is how Nisbett et al act on the one section where I know almost as much as them, how are they misleading me in all the other sections?"

Labeling the paper with the epithet "hugely nurturist" tells nothing about the paper but everything about what you are doing. You are attempting the early dismissal of some viewpoint you disagree with on a more or less political grounds but this has not very much to do with science.

Most cognitive tasks used inside an MRI are about as meaningless as benchmarks. It seems gratuitous to turn this into evidence of intentionally dishonest malfeasance and frame the whole thing as some kind of pseudo-political debate. Just engage the data, please?

Setting aside the political tone you've taken here: the idea that nature and nurture are dichotomous (or can even be meaningfully separated) is not supportable.

It has been observed many times that because heritability includes a genes x environment interaction term, it does not mean that something is 'genetic' - and real-world examples have been provided in this thread.

You cannot build an adequate understanding of development on the caricature that there is a dichotomy between 'nature' and 'nurture'. DNA and RNA cannot do anything without a developmental environment. You do not have any organism without development, which necessarily occurs in an environment. There are strong adaptive reasons for learning in big primates and it is well known to occur. On the other hand, you do not have development or learning without machines to implement them; these are not built without genes but neither can genes build them in a vacuum. It is a perpetual interchange and the components are viciously complementary and embedded in the same feedback loops to a point where it is nearly meaningless even to argue about nature vs. nurture.

> Labeling the paper with the epithet "hugely nurturist" tells nothing about the paper but everything about what you are doing. You are attempting the early dismissal of some viewpoint you disagree with on a more or less political grounds but this has not very much to do with science.

Not relevant to my point about the one-sided presentation.

> Most cognitive tasks used inside an MRI are about as meaningless as benchmarks. It seems gratuitous to turn this into evidence of intentionally dishonest malfeasance and frame the whole thing as some kind of pseudo-political debate. Just engage the data, please?

I don't see what MRIs have to do with this... the DNB studies that matter are, at core, very simple: you give someone a Raven's or BOMAT test, randomly train them on DNB or not, and give them a second test.

> Setting aside the political tone you've taken here: the idea that nature and nurture are dichotomous (or can even be meaningfully separated) is not supportable.

Everyone knows that there is in IQ or psychometrics in general a continuum of positions from nurture to nature, and while only ideologues take a 100% position and everyone sensible acknowledges that there's substantial contribution from both, there's still a very big difference between someone like Nisbett and, say, Arthur Jensen.

I don't know what you're talking about with your dichotomies and caricatures, and I don't really care: because it's not relevant to my point about how accurate a presentation of evidence this Nisbett et al 2012 paper is.

From the article: "The American Psychological Association created a panel of eminent researchers to write a summary of what was known about intelligence, which would presumably contradict many of these claims."

"...would presumably contradict" is right, of course, because the APA is one of the most political organizations in America. An article published in The American Psychologist (the APA's own journal) describes how "a past APA president urged psychologists to advocate radical leftist positions and 'explicitly blend our data and values in order to make strong arguments for the kinds of [radical] change we think is necessary.'"

The people the APA chooses as "eminent researchers" to summarize "what is known" just aren't going to include anyone who doesn't promote their political agenda, leading Willingham to the "would presumably contradict" comment. What they would "find" would be a foregone conclusion, by policy, given the nature of the APA.

A study was conducted in which a liberal, a conservative, and a centrist independently rated the political leaning of articles published by the APA in The American Psychologist. The results, published in The American Psychologist itself, found the APA's published articles to be 97% liberal vs. 3% conservative, with a 93% correlation among the different raters.

This doesn't make any particular claim about IQ right or wrong, but it does mean that you might want to take the APA's word about "what is currently known" about a politically controversial issue with a grain of salt. If other things had been found (and they have), would the APA's hand-picked "eminent scientists" be sure to tell you?

[ See a lot of Philip Tetlock's articles on the topic (use Google Scholar, I'm lazy.) Also, see this in The American Psychologist on the APA's own website: http://psycnet.apa.org/index.cfm?fa=fulltext.journal&jco... ]

Surely you're aware that a tremendous amount of ink and (social-)scientist hours have been spent doing "science" with the presumption that there "are no genes for IQ" etc., so it makes sense to be on guard against biased writing (at least by publication/file-drawer bias) on the topic.

You have gwern wrong. He's an unbiased scientist on this topic.

At best this is "the other guy swung first." At worst it is just a straw man. What you claim the other guys do is irrelevant. Territory defense is irrelevant. Facts are relevant and fist-fights do not uncover them. Why can't the critique proceed on a higher level than "those Xists are deliberately lying again"?

If your way of judging a paper is to look at who wrote it, then conclude that the paper is bad based on some kind of guilt by association with the "wrong school" then you are not being honest with yourself.

The nobler objective is not to discredit and guard against "nurturists" but to do justice to reality. Cognitive science shouldn't be so much like a kung fu movie...

[To gwern, unprovoked] You are attempting the early dismissal of some viewpoint you disagree with on a more or less political grounds but this has not very much to do with science.

[Next reply] Why can't the critique proceed on a higher level than "those Xists are deliberately lying again"?

You seem to be suffering from some cognitive dissonance here.

I'm more worried about this:

> There is not a single mention of the many failures to replicate, methodological critiques, or skeptical meta-analyses about n-back.

Can you refute that?

If you think I am defending the paper because I am its ideological ally, you have not understood what I said

Oh, this wasn't a jab at you. Rather, that's the part of grandparent's post that I think is the most concerning. I just don't have the knowledge and skills to see if it's true, so I was asking you.

Usually, part of the science process is to analyze results in the context of similar work. If the authors are indeed cherry-picking and ignoring counter-results instead of acknowledging them, then that's bad.

To check your biases what percentage of someones Height is based on DNA vs environmental factors? Ok, now compare that with IQ.

In the US environmental factors represent ~20 point shifts in IQ. However 50 point differences are not all that uncommon (75 vs 125) even among family members. Which suggest huge differences based on DNA.

PS: When the average nutrition level increases the importance of DNA also increases.

Please step back a bit.

Let's say you are measuring IQ (whatever it indicates) in some giant between-subjects design or meta-analysis which also includes some number of "independent variables" outside your experimental control. Then you do some kind of multiple regression.

What you are doing is building a very high-level, black-box model finding maximum likelihood parameters to fit some observed data. Each underlying data point is a slice of a snapshot of the behavior of a very complex system.

This is worthwhile insofar as we can account for variance that we might see in future samples and can therefore predict and confirm that we have an understanding of the system. It doesn't actually give us visibility into the complex system because regression terms rarely correspond to anything concrete. This offers only the vaguest possible constraint on attempts to decompose the overall effect into causal factors.

The weights in the regression do not, individually, have a meaningful interpretation outside of the model. (The implication and meaning of a term in a theory depends on the meanings of other terms in the theory).

But for some reason we decide to disregard this, and are primarily interested in which weight is bigger. And the reason we are interested is as a way of showing which ideological school is right or wrong: where the ideological schools are some version of "DNA is so important" and "environment is so important". If one school is vindicated - what? Everything they say is true?

We are testing hypotheses, not people. To badly paraphrase Popper: we send our theories to die in our stead...

Are you getting an idea of what I am saying about nature vs. nurture here or are we just talking past each other?

The value of such a simple model is not what it directly tells you anything but when it stops working you have a strong hint that something interesting is going on. Suppose you find a town where the IQ is 7 points above what you would expect after accounting for the children's socioeconomic situation AND their parents IQ scores. Sounds interesting right, except without the proper weights you can't really do that analysis in the first place.

I hope most people want to identify the influences on IQ so they can try to change them, not so they can vindicate their preferred school of thought.

At least you're not succumbing to the Gell-Mann Amnesia effect, gwern.

Heh. And I started reading the paper with such high hopes when it came out months ago, too.. For those not familiar, realitygrill is referencing a classic Crichton quote:

"Media carries with it a credibility that is totally undeserved. You have all experienced this, in what I call the Murray Gell-Mann Amnesia effect. (I call it by this name because I once discussed it with Murray Gell-Mann, and by dropping a famous name I imply greater importance to myself, and to the effect, than it would otherwise have.) Briefly stated, the Gell-Mann Amnesia effect works as follows. You open the newspaper to an article on some subject you know well. In Murray's case, physics. In mine, show business. You read the article and see the journalist has absolutely no understanding of either the facts or the issues. Often, the article is so wrong it actually presents the story backward-reversing cause and effect. I call these the "wet streets cause rain" stories. Paper's full of them. In any case, you read with exasperation or amusement the multiple errors in a story-and then turn the page to national or international affairs, and read with renewed interest as if the rest of the newspaper was somehow more accurate about far-off Palestine than it was about the story you just read. You turn the page, and forget what you know."

I never knew it was the "Murray Gell-Mann Amnesia effect" but I've been using this exact line of reasoning for many years when discussing the validity of stories read and watched in the media. Interestingly I discovered it as a kid reading a newspaper article about video games something I was very much into at the time. The were talking about the Sega Genesis and the Super Nintendo and at least half of the article's "facts" were just flat wrong and many of the opinions were far left field of what a legitimate gamer would really think. That's when I made the connection. If this story which is something that I am intimately familiar is so utterly wrong then...what about the things I don't know about. That was about the time I stopped paying so much attention to the general media.

I didn't know it had a fancy name though.

> I didn't know it had a fancy name though.

Well, by giving it that, I imply greater importance to myself, and to the effect, than it would otherwise have!

It sounds like you are hijacking the paper to talk about a pet theory. Did you find a cite on p11 about DNB? They refer to cognitive exercise, but not using that particular method. Whether that method is effective or not is orthogonal to their point.

Huh? They spend almost an entire page talking about DNB and WM training! (And BTW my points about DNB apply just as well to WM training in general.)

> Whether that method is effective or not is orthogonal to their point.

You are wrong. It is very germane whether it works.

Okay, I found the reference on page 10. Somehow my keyword search didn't work and we didn't number pages the same way.

Not sure if this is true, but I heard recently that the best predictor of IQ is actually the gene that controls determines the size of your mom's vagina, because that is what mediates the risk of brain cell loss due to lack of oxygen at birth. Kind of a funny, but also quite telling about the state of genetics.

Not sure if this is true

That's definitely NOT a well replicated finding. In general, no study has ever shown any single-gene allele variation with strong effect on IQ across the general population. There are rare genes (but, really, mostly rare chromosome abnormalities) that have devastating effect on IQ, resulting in mental retardation, but the variance in IQ in the general population above and below the population median is still quite mysterious as to whatever genetic basis it has, as the references I've already shared in this thread will make clear.

After edit: has anyone got a contrary example to the general statement I'm making here? I gather someone disagrees with the statement, but I'm not seeing any citations posted in reply. Feel free to check the citations I've already posted in other replies in this rapidly ramifying thread if you disagree with me and would like to look up facts on the matter.

The two tables here identify specific polymorphic genes and linkage regions predictive of IQ: http://www.psy.ed.ac.uk/people/iand/Deary%20(2009)%20Hum%20G...

You didn't speak about the amount and reliability of prediction of IQ in your kind reply. I have referred to that publication. The publication by Deary and Johnson you link to was published in 2009. I was quoting a more recent publication by Wendy Johnson, a frequent co-author with Deary at Edinburgh, in one of my other replies in this thread. Here are a couple of publications by Deary, Johnson, and various co-authors with more recent publication dates than what you have kindly linked:

The review article "The neuroscience of human intelligence differences" by Deary and Johnson and Penke (2010)


"At this point, it seems unlikely that single genetic loci have major effects on normal-range intelligence. For example, a modestly sized genome-wide study of the general intelligence factor derived from ten separate test scores in the cAnTAB cognitive test battery did not find any important genome-wide single nucleotide polymorphisms or copy number variants, and did not replicate genetic variants that had previously been associated with cognitive ability[note 48]."

Johnson, Penke, and Spinath (2011) "Understanding Heritability: What it is and What it is Not"


"Presuming this is correct and, as Visscher and Keller appear to have implied, applicable to most behavioural traits, this indicates that literally thousands of genes are likely involved in each trait, with no single polymorphism having substantial effect, which is the quasi-infinite model to which Munafo and Flint refer. Whatever would we as psychologists do with such information?"

There are more publications on the issue where these came from. I am familiar with the current literature on the subject, both from an online discussion group hosted by the Behavior Genetics Association and from a weekly "journal club" during the school year (at which I met Wendy Johson, the co-author of the publication you linked to, and of other more recent publications I am linking to in this thread). The hope of many behavior genetics researchers was finding a simple genetic model of normal allele variation in just a few genes having a large and consistent influence on IQ in the normal range. That hope has been dashed by the data as further studies have been conducted, and as researchers attempt to replicate the studies of earlier authors in new data sets.

Conceded and upvoted.

Given the prevalence of c-sections and episiotomies, highly unlikely. In 2010, a full third of US babies were not born through the vagina.

That is funny, but babies "breathe" through the umbilical up to several minutes after birth, so I'm sure it has nothing to do with "brain cell loss" or oxygen.

That's assuming the birth goes correctly though. If the umbilical cord is wrapped around your neck and you're coming out breech then that's another story. My understanding is that it has a large effect in a small number of cases.

We're talking about "the best predictor of IQ" which is not the same thing as having a large, negative effect in a small number of cases.

Great quote from page 8 of the actual report:

"In particular, there is clear evidence that school affects intelligence."

Intelligence is traditionally measured through testing. School is the only place people generally practice test taking. Ergo, it makes sense that school affects the results of intelligence tests, but perhaps not in the way you might initially think.

In a good way, or a bad way?

Some people, and the referenced paper, are citing Jaeggi's dual n-back as evidence that interventions can positively affect g(F) (fluid intelligence).

I would like to mention that Jaeggi's results, and working memory training in general, have not been replicated.

The main issue with Jaeggi's experiment, is that proper controls were not used.

For a careful examination, and I would say thorough debunking of Jaeggi's results on dual n-back and g(F) improvement by training working memory, please read:

No Evidence of Intelligence Improvement After Working Memory Training: A Randomized, Placebo-Controlled Study. Redick, Thomas S.; Shipstead, Zach; Harrison, Tyler L.; Hicks, Kenny L.; Fried, David E.; Hambrick, David Z.; Kane, Michael J.; Engle, Randall W. Journal of Experimental Psychology: General, Jun 18 , 2012, No Pagination Specified. doi: 10.1037/a0029082

The best investment a parent can make to improve the child's IQ is DHA, omega 3 fatty acid. It is a key ingredient of a brain, and a typical diet is very deficient in DHA.


Additionally, checkout the: http://www.omega3.org/

Most of the fish oil/IQ links I know tend to either be poor quality studies, show no effect, or show a fade-out... For example,

> Supplementation of a mother’s diet during late pregnancy and 3 months postpartum with long-chained fatty acids has also been demonstrated to improve cognitive performance in human children (Helland et al. 2003). http://www.pediatricsdigest.mobi/content/111/1/e39.full

But to follow up: Helland et al 2008 http://pediatrics.aappublications.org/content/122/2/e472.sho...

> CONCLUSION. This study suggests that maternal concentration of n-3 very-long-chain polyunsaturated fatty acids during pregnancy might be of importance for later cognitive function, such as sequential processing, although we observed no significant effect of n-3 fatty acid intervention on global IQs. Neonatal fatty acid status had no influence on BMI at 7 years of age.

(One may not be surprised inasmuch as most efforts to boost IQ in kids like the Abecedarian project show fadeout.)

I agree in regard of fish oil quality. That's why I use algae derived DHA supplements.

He meant that the studies are of poor quality, not that the studies only used poor quality fish oil.

Yeah, you are right.

And the second link I've posted is wrong, I meant to post this one: http://www.dhaomega3.org/

This article should be titled, “The latest findings on IQ” because IQ score and “intelligence” in a general sense are very different things. Plenty has been published on the inherent cultural and gender biases in IQ testing.

Statements like “when babies from poor families are adopted into wealthy families, their IQ goes up” are almost devoid of information because the IQ test itself favors the type of “intelligence” valued by the educated, wealthy class.

In my opinion the reason poorer people have less IQ then wealthier people, and also why adopted poor babys into middle class homes have higher IQ's comes down to what they spend their time thinking about. Poorer people spend their time worrying about food, money and basic needs. This occupys alot of their thought. Richer people don't need to worry about the basic needs and spend their time worrying about larger more complicated things.

Nitpicking but this seems like a contradiction: "It is noteworthy, for example, that at a given level of IQ, Chinese have smaller frontal cortexes than Americans (Chee, Zheng, Goh, & Park, 2011), although Chinese brains as a whole may be larger than those of Americans (Rushton, 2010). Even with brain size equated between Chinese and Americans, the frontal cortex is larger in Americans (Chee et al., 2011)."

The title is misleading. This is not about intelligence, this is about IQ, and that's hardly the same thing. IQ has never been a reliable measure for anything, and something you can improve on by training/repeated exposure is certainly not linked to intelligence.

Studies have shown that the first 5 years of a child's life is when the brain develops the most. Proper nutrition and exposure to simple problem solving will significantly increase the chances of the child having a higher IQ.

I thought it would be interesting to note that my karma score seems to be going up and down a lot on this topic in short periods of time. On other topics, it seems to increase slowly. I'm trying to think of what deeper conclusions could be drawn from this that people have what appear to be strong and varying opinions on something that should be rather scientific and objective.

It can't be scientific and objective, because it is not measuring something scientifically and objectively defined and most of the differences being discussed can be erased by manipulating the testing circumstances.

That doesn't mean it is never worth measuring, but it seems particularly silly to obsess over IQ when better data on actual outcomes exists for things like educational interventions. The best applications of IQ are in identifying areas of deficit in individuals (one definition of learning disability is an area of cognitive performance that varies significantly from all others.) The worst applications of IQ are to funnel more resources to already-advantaged children or to make demographic generalizations. Given that, it hardly seems unreasonable to mostly ignore the IQ-obsessed research and focus on specific, repeatably-defined cognitive tasks instead.

We cannot engage into this kind of discourse until every party agrees on the definition of "intelligence," and whether intelligence is biological.

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