Wednesday, November 16, 2011

Direct Evidence that Intelligence is Half Genetic: New Hope for Closing the Achievement Gap?

Many people believe that intelligence, like most human characteristics, is affected both by genes and environment.

Indeed, studies of fraternal and identical twins, especially those of identical twins raised apart, summarized in the chart above and, for example, THIS, provide strong evidence that intelligence is roughly half genetic. A survey of 661 experts on intelligence found that the large majority believe intelligence has a significant genetic component.

But there hasn't yet been an analysis of actual genomes to prove that...until now.

THIS study of 3,511 people's genomes was published on the prestigious last month but remains largely unreported by the media. The abstract reports, "Our results unequivocally confirm that a substantial proportion of individual differences in human intelligence is due to genetic variation."

What are the implications?

The bad news

This has to be a blow to educators and social policymakers, who, for a half century now, have been betting billions of tax and charity dollars that the achievement gap could be significantly reduced or eliminated by redistributing resources to improve the environments of low-achieving children and adults by more spending on education, job training programs, self-esteem programs, etc. But just as in a long-distance car race, tuning-up a VW Bug that's running miles behind a Porsche doesn't make it likely to catch up, it appears ever less likely that tuning-up low achievers' environment will close the achievement gap to the extent we all hope it will.

Indeed, that study may help explain why, despite massive expenditures on the widest range of such programs, from Head Start (which, in the definitive metaevaluation, alas has been found to have no impact on the achievement gap) to Stop Drop, the achievement gap remains as wide as ever.

Especially in this era of massive federal, state, and local deficits, we might want to ask ourselves how wise is it to continue to reallocate billions of dollars from gifted education to special education, from regular education to compensatory education. Indeed, our core federal education mandate, No Child Left Behind, and other major programs such as Title I, plus much nonprofit funding do that.

The good news

The good news is that the Nature study would seem to point to a new direction and new hope for reducing that achievement gap. In light of that study, the next steps would seem to be to discover the specific genes responsible for intelligence (something China is already doing) to develop a safe and ethical way to replace defective genes and then making available, on a purely voluntary basis, the option to have that gene therapy so prospective parents could help ensure that their kids don't start life with a genetic strike or two against them.

To ensure that option doesn't exacerbate the gap between rich and poor, it should, like most medical services, be fully covered under MediCal (the free health care program for the poor,) and under ObamaCare. In addition, special outreach to low-income communities should be provided, emphasizing both the therapy's availability and its being completely optional.

I would imagine that the therapy would most benefit families of multigenerational low achievement. If my parents were low achievers, I were a low achiever, and now I heard that intelligence was half genetic and there was a free, safe, and effective therapy that would improve my children's chances of having high intelligence and, in turn, be more likely to be successful in school and in career, I'd sign right up.

Here is the study's abstract.

Genome-wide association studies establish that human intelligence is highly heritable and polygenic

G Davies, A Tenesa, A Payton, J Yang, S E Harris, D Liewald, X Ke, S Le Hellard, A Christoforou, M Luciano, K McGhee, L Lopez, A J Gow, J Corley, P Redmond, H C Fox, P Haggarty, L J Whalley, G McNeill, M E Goddard, T Espeseth, A J Lundervold, I Reinvang, A Pickles, V M Steen, W Ollier, D J Porteous, M Horan, J M Starr, N Pendleton, P M Visscher and I J Deary

General intelligence is an important human quantitative trait that accounts for much of the variation in diverse cognitive abilities. Individual differences in intelligence are strongly associated with many important life outcomes, including educational and occupational attainments, income, health and lifespan. Data from twin and family studies are consistent with a high heritability of intelligence, but this inference has been controversial. We conducted a genome-wide analysis of 3511 unrelated adults with data on 549692 single nucleotide polymorphisms (SNPs) and detailed phenotypes on cognitive traits. We estimate that 40% of the variation in crystallized-type intelligence and 51% of the variation in fluid-type intelligence between individuals is accounted for by linkage disequilibrium between genotyped common SNP markers and unknown causal variants. These estimates provide lower bounds for the narrow-sense heritability of the traits. We partitioned genetic variation on individual chromosomes and found that, on average, longer chromosomes explain more variation. Finally, using just SNP data we predicted ~1% of the variance of crystallized and fluid cognitive phenotypes in an independent sample (P=0.009 and 0.028, respectively). Our results unequivocally confirm that a substantial proportion of individual differences in human intelligence is due to genetic variation, and are consistent with many genes of small effects underlying the additive genetic influences on intelligence.


euquant said...

"General intelligence is an important human quantitative trait that accounts for much of the variation in diverse cognitive abilities..."

To be sure intelligence makes a big difference and few dispute that there is a hereditary origin for it.

But what about the other key personality traits?

I've always thought intelligence is kind of overrated. They say that conscientiousness and assertiveness (lack of agreeableness) are also important for success. Are these heritable too?

For one I would gladly trade some of my gifts of a few dozen IQ points for an extra portion of self-discipline and organization. While everyone has a particular set of gifts and it's best to make the most of them, distractible dreamers (like me) aren't going anywhere without follow-through no matter how clever and creative they think they are.

euquant said...

As far as your political points go, I'm not sure I follow.
But being a layman myself, I hardly feel right contributing my naive outsider opinions to a discussion among so many teachers and experts like yourself with years of experience and advanced degrees in education.

Your metaphor of the VW and Porsche isn't bad, but I don't think anybody is under the illusions that we can make a VW perform like a Porsche. Perhaps it would at least make sense to help get that VW running well enough so it can get from A to B without breaking down and causing a traffic jam that makes everyone pretty miserable. Indeed there is nothing wrong with a modest car like a VW as many proud Beetle drivers would surely attest, religiously keeping them polished shiny and well-running - just like many Porsche drivers do. Another thing, I suspect keeping a temperamental high-performance machine running at peak potential to be more demanding than just keeping that Chrysler minivan running well enough to get to work, school and home.

I suppose this is the point where we get to your advocacy of enhancing the status professional and vocational training - indeed opportunity, achievement and dignity for everybody.

Sure some are blessed with real gifts, but not all of these are really motivated to take advantage of the resources made available. I imagine it not only being a greater personal satisfaction, but also a more sensible investment of resources to help a less gifted individual fulfill his potential if he's possessed with the hunger and the motivation to learn even if it's a struggle compared to another who might relatively have more substantial natural brilliance but doesn't mind wasting it because he has no interest to learn.

In short, what is the bigger problem, differences in natural intelligence or motivation? From my not so recent school experience, the big problem it wasn't that they were wasting resources so much the less intelligent but rather on the unmotivated and disruptive.

Even if I'm splendidly ignorant of the actual execution, I really respect the spirit behind "No Child Left Behind." I don't know why kids aren't learning and what in particular is broken, the schools and teachers, the community, media and society at-large or closer to home the pupils and the families. Nevertheless from where I stand it seems like a sick society that idolizes entertainment and sports stars while we only give lip service to the value of education - for those who can't make it big in such a big way.

"Hey kids, eat your tuna and broccoli and then go read and do your homework. I’ll be in front of the tv with my Twinkies and corn chips drinking a beer if you need me. "

For too long citizens have pretended to care about education and we've been satisfied "just trying our best." The coach is right. Trying is for losers. Results are what matters. So instead of giving up and conceding defeat in education like we've conceded so many other places of our societies where civilization has retreated to leave violence and gangsters to run amok.

So when they said we're not going to surrender the schools, it earned my respect and gave hope… at least until the generals of the divisions of teachers unions occupying and the citizens there showed they were hardly interested in joining the fight.

I have neither school age children, nor am I in the United States, but when I hear from peers and colleagues in the US about how high property taxes are and how miserable the schools are and how it's essential to pay ridiculous amounts for private school fees, I'm saddened to think how the war has probably already been lost and how you dear Yanks have already surrendered to resignation.

Anonymous said...

I personally think it would be better to accept that some people are not very bright, and that they don't deserve to be seen as "less thans" the way many smart people see them. It doesn't necessarily imperil the liberal idea of giving everyone a certain equality of dignity; it might bolster it, since nobody chooses their level of intellectual ability.

To quote Charles Murray:

"The topic of race and genes is like the topic of sex in Victorian England. The intellectual elites are horrified if anyone talks about it, but behind the scenes they are fascinated. I will say it more baldly than Dick and I did in the book: In their heart of hearts, intellectual elites, especially liberal ones, have two nasty secrets regarding IQ. First, they really believe that IQ is the be-all and end-all of human excellence and that someone with a low IQ is inferior. Second, they are already sure that the black - white IQ difference is predominantly genetic and that this is a calamity -- such a calamity indeed that it must not be spoken about, even to oneself. To raise these issues holds a mirror up to the elites' most desperately denied inner thoughts...

But when people say one thing and believe another, as intellectual elites have been doing about race, sooner or later the cognitive dissonance must be resolved. It usually happens with a bang. When the wall of denial gives way, not only will the received wisdom on race and IQ change, the change will happen very rapidly and probably go much too far. The fervor of the newly converted is going to be a problem. I fully expect, if I live another twenty years, to be in a situation where I am standing on the ramparts shouting: "Genetic differences weren't a big deal when we wrote The Bell Curve and they still aren't a big deal.'' "

I tend to take this view. It's unfortunate that blacks are, on average, less intelligent than whites, but it's much worse to censor it, or to see it as something that absolutely must be changed, without coming to terms with it first.

euquant said...

When I was a teenager I worked with a downs syndrome guy in fast food. Sure we wern't going to give him the keys to the store, but he had a great attitude, worked hard and the team and the customers loved him.

So he'll never be on top, but I liked his bright attitude better than that of all the arrogant pricks I knew from my elite university and so on.

Perhaps I've been brainwashed by the political correctness to a degree, but I get an allergic reaction whenever somebody dwells on the fact that certain communities (i.e. blacks) are statistically less intelligent. I understand the motivation to get us to stop fighting a hopeless battle of fixing some statistical gap.

Perhaps we should do it like the French; they try to promote national unity by not keeping racial statistics like that (not working out so well I fear.).

I wish they would just calm down and stop obsessing about all that racial business and focus on helping little Billy or Suzy become the best their potential allows.

I'm still waiting for the scientific revelations about our genetic destiny that determine our drive, fortitude and courage. We already know that some are more generously endowed in the mind but are some just born with more heart?

THM said...

I have doubts about the implications of these studies. While I think there is probably sweet spot for IQ that translates into real world achievement, it's likely that sweet spot is within the grasp of any socioeconomic group.

IMO, the elephant in the room--or the VW Bug, as you put--is culture. For whatever reasoon, it is increasingly acceptable to suggest genetics/prenatal care/whatever lead to differences in achievement. But it raises eyebrows and indignation to suggest culture. Nevermind, for example, that charter schools can increasingly close various achievement gaps once they undue the lousy cultural backage that many of their students come in with.

Further, I have my doubts about the merits about gifted children or gifted education. Take a look at the MENSA crowd: it's like the late-shift from Hollywood Video. It's underachievers galore, which is likely due to a lack of social intelligence -- a much more crucial trait for achievement.

It's fitting that Occupy Wall Street is going on right now. From what I've seen, most are articulate, fairly intelligence, and likely have above average IQ's. It's even more fitting they protest outside the offices of people, who are likely less intelligent, less articulate, but who would still bury them in any competitive, Darwinian environment.

Marty Nemko said...

THM, I am interested in your statement, "Charter schools can increasingly close various achievement gaps once they undo the lousy cultural baggage that many of their students come in with."

I have looked at charter schools for a long time, and while there was one--some Indian/Native American school in Oakland that reported, at least for one year, impresssive results, and another in New York touted by a very charismatic Black guy whose name I can't remember, all school-based "miracles" that have, over the decades been touted eg. KIPP, EdTrust-an Jose, the Michelle Rhee DC "Miracle), and ther older ones: Central Park East, Marva Collins, Jaime Escalante, have been found to not be scalable and/or have invalid or even fraudulent data. I have spent my life looking for The Answer within education. I'm still looking and so would welcome directing me to scalable, achievement-gap cutting programs that continue to do so after the first couple years of a super-dynamic leader's exhausting efforts.

Jeffrie said...

euquant said: "Perhaps I've been brainwashed by the political correctness to a degree, but I get an allergic reaction whenever somebody dwells on the fact that certain communities (i.e. blacks) are statistically less intelligent."

I don't consider myself politically correct, but I agree with the rest. When the average person says that to me, it seems they've already judged me & people like me without getting to know me. It rubs me the wrong way.

A lot of different people have told me how smart they think I am. I've never taken an IQ test, so I don't have an official number to prove or disprove it. But somehow everybody just "knows" that, as Anonymous said on November 17, that "It's unfortunate that blacks are, on average, less intelligent than whites."

As for the topic at hand ... it's not going to be a blow to educators & policymakers. As Marty said, it has been largely unreported by the media, and it will likely remain so, unless they want to tear it apart like they did with "The Bell Curve" when it first came out. They continued to say that all they needed was more money to improve the environment, and they will keep right on saying that.

I don't know when, if at any time, this could change, but if I were to guess, it would not be now. We have invested too much in the idea that only the environment needs to change.

THM said...

American Indian Charter in Oakland would be a good place to start. The middle school and highschool test scores typically fall in the Top 5 for all of California. The middle school was recently the highest peforming in the entire state, outpeforming public schools around Silicon Valley (arguably the brainiest and most affluent place on earth).

There are others. The approximately 100 KIPP schools tend to consistently outperform comparable schools. SEED Charter School in DC takes a different approach by boarding the students. In each case, the schools go heavy on the basics and create a culture that entirely different from students' home lives. Are these the places scalable? That is relative, but they are certainly more scalabe than incarceration, medicaid, and lifelong government assistance.

While a high-IQ pill would be great (I would stand in line for mine), I still have my doubts about its ability to close persistent socioeconomic divides. If I had to ballpark it, I would say innate, testable IQ accounts for maybe 30% of success. But again, that's just me.

Consider the case of Chris Langan. He grew up in a broken home. He dropped out of college, before bouncing from one fairly menial job to another. A fairly unremarkable working class story, until you consider his IQ -- the highest ever recorded at 200.

Again, I think there are just too many moving parts in all of this.

Greg said...

Great study. There should be greater awareness of research like this. IQ is only part of the picture though; determination, willpower, courage, endurance, motivation, and especially social/emotional/Machiavellian intelligence are probably much more important than IQ. Are traits such as these quantifiable? I would be interested to know if you have run across such studies...

I used to think tampering with the genome was morally wrong, but more and more, I too am starting to think that since it's impossible to totally dissuade people from having more children in an already very populated world (nor should we necessarily aim for this), the best we can do is to make sure that we give birth to as many "high-quality" human beings as possible. Better to engineer smarter, healthier, stronger beings than let nature take its course and give us an increasing number of dumb, unhealthy, and weak offspring. At the end of the day, someone will have to take care of these people in one way or another...

This is a slippery slope, and if the science is imperfect (it very well might be), we may end up creating far more problems than we solve by altering the genetic code. You're talking about tampering with hundreds of millions of years of evolution. The potential side effects are most worrisome...

Marty Nemko said...


Be careful what you tout. Over the past 40 years, I've seen countless programs for vulnerable populations" with one or two years of high test scores only to find that the students were cherry-picked (e.g., Jaime Escalante) the data was cherry-picked (KIPP) the test scores were fraudulent (The Michelle Rhee "Miracle" in DC), or in the case of American Indian Charter, it's way too early to tell. We do know that the anecdotal evidence--e.g., is not good--Heavily teaching to the test, not really educating kids in a real sense. We also know that the principal Ben Chavis is--let's be polite--not averse to publicity. It's a formula we've so often seen be a flash in the pan--for example, Marva Collins' school in Chicago, Central Park East in Harlem.

A person who needs to remain anonymous, who is among the nation's most respected education leaders said, confidentially, "A model program is one you haven't visited."

Here's an article on the overoptimism re some of the schools you tout:

If you are who I think you are, you live not far from the American Indian Charter School. I invite you to pay a visit. Perhaps you'll be impressed. If so, do post a comment. But you may find things a bit different than you might expect---if they let you see what's really going on in the classrooms rather than get a salespitch from an administrator.

Marlo said...

Marty, why beat around the bush with words like "low achievers" and "poor people"? Surely you think that the study has implications for matters of race/ethnicity.

I haven't read the whole study, but the abstract discusses individual differences in intelligence. I'm not sure where it says--covertly or otherwise-- that the distribution of genetic markers for intelligence differs substantially between whites and blacks. That some folks interpret the results as such is indicative of little more than wishful thinking on their part.

If standardized tests are in fact the best measure of innate intelligence, then there's no evidence that blacks are less intelligent than whites. For example, one study from Israel documents the IQ gains of a group of Ethiopian immigrants. After being taught cognitive strategies that are valuable in the western world, they scored as well as their white counterparts on multiple ravens progressive matrices exams.

As with any study, the conclusions were not written in stone. But there's no reason to believe that that they were driven by political correctness. Nor do homeschooled black children in the U.S. perform poorly on IQ tests.

Maria Lopez said...

If your parents were low achievers and you were a low achiever, you would be suspicious that any such program was fraud designed to produces children who were agreeable and obedient to corporate and government dictat.

Maria Lopez said...

I also think that if the mechanism through which some genes produce higher IQs were known it might be possible to provide a drug or supplement to pregnant women which would act similarly to the product of these genes. This would be better in a couple ways as it would be less paranoia inducing than a more elaborate procedure and less likely to require IVF, something that is expensive and inconvient for mothers.

ST said...

There's a bunch of stuff resulting from Google searches if you type "highest IQ". Supposedly, Marylin Vos Savant had a (mental status ratio IQ used for children) IQ of 228, but an adult (using standard deviations) IQ of 180. Chris Langan is listed as 195, but Kim Ung-yong has one listed as 210. You see Einstein listed as all of 135, 160, & 180. (?)

You can read about many of these very smart people had difficulties or were bored with school. Probably both because the subject matter was easier for them, or they didn't like the confinement of being in "the system" in which the schools and educational systems operates.

Now, let's say that someday, we do have the ability to apply intelligence gene therapy and much like how dogs were bred over many generations (compared to the much slower process of evolution) humans become within current IQ ranges of say 140-160 being the 95th percentile (versus the current 70-130), then there will still be a "bell curve". I could also imagine purposely proventing gene therapy to a "class" of individuals to create a brute work force, a group of people who didn't have high aspirations and would be willing to work for the "elite".

Marty Nemko said...


Yes, there would still be a bell curve, but a world of far more intelligent people would, net, make for a better world. Of course, some people use intelligence for nefarious purposes, but most do not.

And yes, as with all powerful interventions (from heart drugs to dynamite, we must be very careful in its use and regulation. But that's not an argument for banning such interventions.


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