[Symmetry]

"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.

[mistercow]

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.

[kenjackson]

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.

[scott_s]

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

[jessriedel]

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."

[scott_s]

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

[Symmetry]

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

[CWuestefeld]

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?

[Symmetry]

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.

[rustynails]

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?

[CWuestefeld]

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

[pessimizer]

Poor isn't a culture.

[mistercow]

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

[gnaritas]

Actually it kind of is.

[nollidge]

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?

[pjscott]

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.

[nollidge]

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

[stephengillie]

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

[vectorpush]

>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.

http://sfbay.craigslist.org/search/zip?query=tv+&srchTyp...

[randomdata]

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.

[vectorpush]

>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".

[ShawnBird]

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.

[yummyfajitas]

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.

http://webarchives.cdlib.org/sw1vh5dg3r/http://ers.usda.gov/...

[nitrogen]

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.

[maxerickson]

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.

[stephengillie]

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".

[jfoutz]

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.

[Symmetry]

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.

[brittohalloran]

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.

[sageikosa]

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.

[scott_s]

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/

[tokenadult]

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.

[scott_s]

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.

[mokus]

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.

[tokenadult]

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).

http://everythingisobvious.com/wp-content/themes/eio/assets/...

[scott_s]

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.

[SilasX]

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.

[Symmetry]

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.

[scott_s]

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.)

[Symmetry]

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.

[bluekeybox]

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.

[scott_s]

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."