In my experience most scientists are not too clear on the details of intelligence testing, perhaps because the whole area is somewhat in ill repute (except when you want to brag about your own SAT/GRE score!). This despite the fact that the profession of science is skewed toward the right end of the intelligence bell curve. Steve Hsu, a physicist at the University of Oregon (and someone I’ve known for a while in the interests of “full disclosure”) has a nice presentation up in PDF format which summarizes the major points of interest in this area. Worth a skim if you are unfamiliar. Additionally he alludes to future directions in the study of the genetic basis of intelligence using genomics. Here’s his abstract:
I begin with a brief review of psychometric results concerning intelligence (sometimes referred to as the g factor, or IQ). The main results concern the stability, validity (predictive power) and heritability of adult IQ. Next, I discuss ongoing Genome Wide Association Studies which investigate the genetic basis of intelligence. Due mainly to the rapidly decreasing cost of sequencing (currently below $5k per genome), it is likely that within the next 5-10 years we will identify genes which account for a significant fraction of total IQ variation. Finally, I end with an analysis of possible near term genetic engineering for intelligence.
This talk is aimed at physicists and should be accessible even to those with no specialized background in psychology or biology.
Also, in case you are skeptical, Steve is quite aware of the difficulties with the enterprise which he outlines in the presentation assuming that the genetic architecture of intelligence is as he assumes. As sequencing gets cheaper and the sample size of full genomes hits the tens of thousands someone will tackle this, so he and his colleagues figured why not now?
Razib Khan’s degrees are in biochemistry and biology. He has blogged about genetics since 2002, previously worked in software development, is an Unz Foundation Junior Fellow and lives in the western US. He loves habaneros.
May 13th, 2011 at 10:48 pm
When the intelligence genes are found in China, will it really quiet the Western g-doesn’t-exist (multiple intelligences) or IQ-doesn’t-measure-anything crowds?
May 13th, 2011 at 10:54 pm
Would that Grace Kelly’s parents had used something like the gamete sequencing screen as proposed. She couldn’t get into Bennington because of her low math scores.
May 13th, 2011 at 10:55 pm
When the intelligence genes are found in China, will it really quiet the Western g-doesn’t-exist (multiple intelligence>s) or IQ-doesn’t-measure-anything crowds?
you’re a lot more confident that this will work than steve himself is, for what it’s worth. don’t get ahead of yourself.
in any case, i think really they’re almost two separate questions. though you are correct in inferring that symbolically they’re connected. i doubt it will matter if steve finds positive results. there’s a lot history of false positives in this area from candidate gene studies on down.
May 14th, 2011 at 10:03 am
So he suspects within 5-10 years we’ll have identified a few hundred IQ-boosting genes, at which point we can use standard sperm and egg or embryo screening and in vitro fertilization to selectively breed smarter off-spring.
I wonder when the first society will adopt this on a mass scale. My bet would be Singapore in the … 2030s. By 2020 we should have identified the genes. Then maybe a decade of the rich using in vitro techniques to produce smarter children. Then a small, autocratic country like Singapore — one with minimal hang-ups about IQ — could subsidize it’s use for the bulk of society.
Singapore already seems to accept that it’s survival relies on being smarter, better educated, and more productive than other countries to survive and thrive as that rare modern city-state. And the populace there seems comfortable following the diktats of a technocratic elite with few religious and ethnic hang-ups regarding IQ.
How much could a few generations of such selective breeding raise the average IQ of Singapore? Or would most of the gains come relatively quickly from selective breeding at the high end?
May 14th, 2011 at 10:03 am
you’re a lot more confident that this will work than steve himself is
Oh, I don’t know, Steve sounds pretty confident:
“it is likely that within the next 5-10 years we will identify genes which account for a significant fraction of total IQ variation”.
I don’t think it is likely at all. To me, the main problem is the assumption of additivity. I think it is much more likely that the effects are combinatorial. Not just right number of “right” alleles but just the “right” combination of them. If so, N ~ 1-10K would still be hugely underpowered.
May 14th, 2011 at 10:07 am
it is likely that within the next 5-10 years we will identify genes which account for a significant fraction of total IQ variation
Genetic validation of The Bell Curve is unthinkable. Diversity is admission by reason of disqualification. Here is the heavy lifting, more than 90 diversity programs at U/Michigan,
http://www.diversity.umich.edu/programs/
Gentle Reader is invited to locate a single, just one, U/M program for the Gifted. We are where we are because we did what we did. Stupidity is not a bouyant medium, but it is its own engine of creation.
May 14th, 2011 at 10:26 am
Oh, I don’t know, Steve sounds pretty confident:
i’m going off a 3 hour conversation we had. steve is hopeful. but i wouldn’t call him confident.
I think it is much more likely that the effects are combinatorial. Not just right number of “right” alleles but just the “right” combination of them.
within 99% of the distribution it seems to be majority linear effects. are you saying that the combinations break out into linear effects?
May 14th, 2011 at 11:59 am
I know it’s petty to pick on summary flow charts, but anyone who labels the (single) arrow between “genes” and “brain” as “molecular biology” is not having the conversation I want to have.
And Jame, anyone who talks about “the intelligence genes” being found in a geographical location doesn’t belong in the conversation at all.
May 14th, 2011 at 12:01 pm
What is the situation with height?
I thought it was the same as with IQ: hundreds of unreplicated claims from GWAS. Hsu mentions failure of IQ replication, so he seems to be asserting height replication. Is it true?
May 14th, 2011 at 2:06 pm
within 99% of the distribution it seems to be majority linear effects.
Really? Seems based on what? I think that the use of linear models in GWAS is a bit of a lost key and a lamp post situation rather than an evidence for simple additive effects of multiple genes.
May 14th, 2011 at 2:29 pm
Really? Seems based on what?
the narrow sense heritability is 50%ish. probably higher than that in non-deprived environments. this doesn’t deny mechanistic epistatic interactions and such. but if you have two parents you can predict the expected amount of regression to the mean using this as a baseline. also, the standard deviation of IQ of siblings is the same as in the general population, 15 points.
again, don’t confuse GWAS etc. with the behavior genetic aspect. the latter is robust. the interval of narrow sense heritability is .3 to .8 depending on who you talk too and the context (middle to upper middle class environments are going to dampen stochasticity of environmental effect). the genetic architecture is a different issue, as is the effectiveness of genetic and genomic techniques in elucidating the genes controlling the variance.
May 14th, 2011 at 2:40 pm
If Cosma Shalizi says that IQ testing is statistically suspect, then I’d trust Cosma Shalizi.
http://cscs.umich.edu/~crshalizi/weblog/523.html
May 14th, 2011 at 2:46 pm
yes, everyone trusts cosma. that’s fine.
May 14th, 2011 at 3:33 pm
Cosma is brilliant, statistics is his field and he does a review.
Hsu may be right, but he will have to show that first; if he does, he is the first to make a clear inroad on the body length/intelligence/life length problems.
Of course I’m skeptical. Everyone trusts Steve’s awareness of the difficulties. That’s fine.
May 14th, 2011 at 4:00 pm
Cosma is brilliant, statistics is his field and he does a review.
cosma’s post is good, but most people who appeal to it don’t read/understand it (it’s basically now what anyone who is intelligent will point to to support an anti-IQ position). that’s a problem. but that’s life too.
May 14th, 2011 at 5:00 pm
I’d trust Cosma because 1) he knows a heck of a lot more statistics than I do and 2) there’s no evidence that he’s got a political bias in this matter. He’s against dodgy statistics no matter WHO is doing it.
As for me, I’m not convinced that we can measure a unitary intelligence divorced from social context. Culturally-biased tests. Insufficient cross-cultural studies. We may eventually get to the point that we can isolate some genes, or gene constellations, that contribute to some components of the aptitudes that we now group as “intelligence”, and map the biochemical pathways that connect genes and aptitudes. That I’d believe.
May 14th, 2011 at 6:19 pm
As for me, I’m not convinced that we can measure a unitary intelligence divorced from social context.
in my experience the only people who believe in this thing, g as some possibly deep and concrete fact of our neurology, are a subset of psychometricians and their critics. even most psychometricians are much more instrumental in their attitude.
May 15th, 2011 at 3:22 am
what cosma wrote, and it’s true, is that g emerges from factor analysis because IQ subtest scores are positively correlated.
but the positive correlation matrix is the data to be explained in the first place and has been since it was first observed at the beginning of the 20th century!
if you can find a social context where the scores aren’t positively correlated, that would be very interesting and quite novel.
otherwise, it doesn’t matter how you summarize the data, reality is still what it is.
May 15th, 2011 at 12:13 pm
It doesn’t seem to be often noted, but for IVF and embryo screening to useful in raising the IQ of ones offspring, one or more genes of large effect are going to have to be discovered. Suppose there are 100 genes which affect intelligence–each accounting for less than 1% of the variance. How many full-genome sequences are you going to have to run and how many embryos are you going to have to discard to make any observable difference–and would anyone bother?
I happen to believe that Volkmar Weiss is correct and that there is a gene of large effect whose influence can be seen in the way intelligence is inherited in families, but it seems to be a minority opinion.
May 15th, 2011 at 12:25 pm
It doesn’t seem to be often noted, but for IVF and embryo screening to useful in raising the IQ of ones offspring, one or more genes of large effect are going to have to be discovered.
yep. i have suggested that a more practical path would be take a smart person’s genome, clone them, and substitute large effect alleles which alter physical appearance to make them look (and perhaps behave if you find the right loci) more like the parents.
May 15th, 2011 at 2:26 pm
***And Jame, anyone who talks about “the intelligence genes” being found in a geographical location doesn’t belong in the conversation at all.***
@ Miko,
I think Jame is referring to the research being based in China, as opposed to the genes only existing there (if that’s what you were meaning).
***As for me, I’m not convinced that we can measure a unitary intelligence divorced from social context.***
Well, better processing speed is going to be an advantage in most social contexts?
“The UCLA researchers took the study a step further by comparing the white matter architecture of identical twins, who share almost all their DNA, and fraternal twins, who share only half. Results showed that the quality of the white matter is highly genetically determined, although the influence of genetics varies by brain area. According to the findings, about 85 percent of the variation in white matter in the parietal lobe, which is involved in mathematics, logic, and visual-spatial skills, can be attributed to genetics. But only about 45 percent of the variation in the temporal lobe, which plays a central role in learning and memory, appears to be inherited.”
http://www.technologyreview.com/biomedicine/22333/
May 15th, 2011 at 8:32 pm
http://www.lsa.umich.edu/honors/