Slashdot Mirror

← Back to Stories (view on slashdot.org)

Researchers Find Dozens of Genes Associated With Measures of Intelligence (arstechnica.com)

Posted by BeauHD on from the measures-of-intelligence dept.

An anonymous reader quotes a report from Ars Technica: We don't know a lot about the biological basis of our mental abilities -- we can't even consistently agree on how best to test them -- but a few things seem clear. One is that performance on a number of standardized tests that purport to measure intelligence tends to correlate with outcomes we'd associate with intelligence, like educational achievement. A second is that this performance seems to have a large genetic component. But initial studies clearly indicated that the effect of any individual gene on intelligence is small. As a result, the first genetics studies found very little, since you needed to look at a large number of people in order to see these small effects. Now, a new study has combined much of the previous work and has turned up 40 new genetic regions associated with intelligence test scores. But again, the effect of any individual gene is pretty minor. The team behind the new work took advantage of open data to pull together information from 13 different studies, which cumulatively looked through the genomes of over 78,000 individuals. While those individuals had been given a variety of tests, the authors focused on measures of general intelligence or fluid intelligence (the two seem to measure similar things). The genomes of these individuals had been scanned for single base pair differences, allowing the authors to look for correlations between regions of the genome and test scores. Two separate analyses were done. The first simply looked at each base difference individually. That turned up 336 individual bases, which clustered into 22 different genes. Half of these had not been associated with intelligence previously. To provide a separate validation of these results, the authors did a similar analysis with educational achievement. They found that nearly all of the sites they identified also correlated with that. In a second analysis, the authors tracked base differences that cluster in a single gene. Since there are more markers for each gene, this tends to be a more sensitive way of looking for effects. And in fact, it produced 47 genes associated with the intelligence test scores. Seventeen of those had been identified in the earlier analysis, which brought the total genes identified to 52, only 12 of which had been previously associated with intelligence test scores.

15 of 267 comments (clear)

  1. didn't you get the memo by Swampash · · Score: 4, Insightful

    You're not allowed to talk about the possibility of there being a genetic basis for variations in intelligence. Because some genes are more common in certain ethnic groups than others, and then all hell will break loose and you'll get Bellcurved.

    1. Re:didn't you get the memo by ShanghaiBill · · Score: 5, Interesting

      statistical evidence that certain ethnic groups display on average higher intelligence than others (such as whites as compared to blacks).

      IQ is not the same as intelligence, although it is almost certainly highly correlated.
      Whites are not on top. Both Jews and East Asians score higher on average.
      In America, blacks have mean IQ scores about 0.7 SD, or about 10 points, lower than whites.
      Black children have, on average, twice the blood lead levels of white children.
      The first large scale IQ testing in America was of recruits during the First World War, in 1917.
      In those 1917 tests, the average score was 15 points below today's average.
      A century ago, there was a 15 point gap in IQ scores between Protestant and Catholics in Ireland.
      Today there is no gap.

      So is the "IQ gap" caused by genetics? Maybe, but similar gaps in the past were not.

    2. Re:didn't you get the memo by Anonymous Coward · · Score: 5, Insightful

      There is also a long ugly history of even scientists ignoring scientific findings that are socially unacceptable.

      Different mean and standard deviation of intelligence found in groups of people defined through genetic locus controlling for education, culture, diet, and socioeconomic status is one of them.

      The person that can prove four decades of scientific evidence wrong will be quite famous. Until then, everyone tries very hard to ignore the evidence and pretend it doesn't exist, as this paper did.

    3. Re:didn't you get the memo by Michael+Woodhams · · Score: 4, Insightful

      One issue is comparing heritability within a group with differences between groups.

      The old argument goes something like this. Within middle class white Americans, IQ is highly heritable. Black Americans and new immigrants from Eastern Europe (this is around 1910 when there were many such immigrants) score much worse than middle class white Americans on IQ tests. Because IQ is heritable, the Blacks and Eastern Europeans must be genetically inferior.

      There are (at least) two major problems with this line of reasoning. One is that the tests had a cultural bias. This can be as simple as people with English as a second language not understanding the instructions, or just lack of familiarity with the types of questions being asked. Another is neglecting the contribution of environment: the testees may in fact be less intelligent, but because of impoverished childhood rather than inferior genes.

      A good example of this second point is height. Height is more heritable than IQ, but is also affected by childhood nutrition. As a people become affluent, average height increases, even though the genes are not changing.

      --
      Quattuor res in hoc mundo sanctae sunt: libri, liberi, libertas et liberalitas.
    4. Re:didn't you get the memo by piojo · · Score: 5, Interesting

      That doesn't seem like a good enough reason to put the kibosh on the study of intelligence. The racial angle is weak. Everyone that matters knows racial differences are small. But what we have to gain by learning about intelligence is huge. We can learn about learning disorders. We can try to ameliorate the damage of dementia. Granted that this also opens up a can of worms regarding what interventions are ethical, but that's not a racial issue.

      The fact that something could--if you bend over backwards by ignoring the actual numbers--be used to promote racism shouldn't be a reason not to discuss it candidly when the context is bettering everybody's lives.

      --
      A cat can't teach a dog to bark.
    5. Re:didn't you get the memo by Jzanu · · Score: 5, Insightful

      But Jewish populations are genetically distinct, even between small sub-groups. As a whole they are farther from European clusters than many African, and of course are more closely related to Arabs from genetic drift measurements. Races are artificial and are scientifically meaningless; genetics is reality.

    6. Re:didn't you get the memo by jellomizer · · Score: 4, Interesting

      However showing that there are dozen of genes. It would make sense racial factors would be a minor aspect. Also many of our racial distinctions have less to do about genetics and more about culture.
      Intelligence is complex, while we may measure it in terms of IQ but there are many variations of it and a lot of it is also based environment.
      You could have genes that would make you the strongest person in the world, but you never exercised so they are genetically inferior people who are stronger than you because they maximize their potential while you didn't. The same with intelagance you can have the won the genetic lottery in terms of intelligence. But you may not have worked it out, so if you take that IQ test your score wouldn't reflect your full potential.
       

      --
      If something is so important that you feel the need to post it on the internet... It probably isn't that important.
    7. Re:didn't you get the memo by agm · · Score: 4, Informative

      Charles Murray knows this all too well. He's been treated very poorly because of the controversial nature of his research. And from what I can tell he was meticulous in collecting and processing the data that lead him to the conclusion that intelligence has genetic factors. It would be a fluke for anything that has genetic factors to not express some divergence across populations. If your parents are tall there's a higher chance you will be tall. If your ethnicity is known for having dark hair the high chances are your hair will be dark. Similarly with IQ. Murray sought the data, came to this obvious conclusion and has been castigated for it for many years by SJWs who can't handle the truth.

  2. p hacking by eis2718bob · · Score: 4, Insightful

    This is a textbook example of p-hacking. Note the plural in "measures of intelligence", along with "educational achievement" as dependent variables. Something was gonna show a correlation, to the vaunted oh point oh five. What a crock.

    882. We don't even need the links for these anymore, just the number.

    1. Re:p hacking by phantomfive · · Score: 4, Interesting

      It's very possible. The effect found by each of these genes was very small, a fraction of an IQ point. At that small size, I would doubt that I had accounted for all confounding variables. Something as simple as hair color might be a confounding factor, and height certainly would be.

      --
      "First they came for the slanderers and i said nothing."
    2. Re:p hacking by parkinglot777 · · Score: 4, Informative

      It's very possible. The effect found by each of these genes was very small, a fraction of an IQ point. At that small size, I would doubt that I had accounted for all confounding variables. Something as simple as hair color might be a confounding factor, and height certainly would be.

      However, if you really look at the study, you should see that it has NOTHING to do with the GP accusation. I have no idea why the GP is so negative on the study??? Also, how could the post be insightful??? Abstract below...

      Intelligence is associated with important economic and health-related life outcomes. Despite intelligence having substantial heritability (0.54) and a confirmed polygenic nature, initial genetic studies were mostly underpowered. Here we report a meta-analysis for intelligence of 78,308 individuals. We identify 336 associated SNPs (METAL P < 5 × 10^-8) in 18 genomic loci, of which 15 are new. Around half of the SNPs are located inside a gene, implicating 22 genes, of which 11 are new findings. Gene-based analyses identified an additional 30 genes (MAGMA P < 2.73 × 10^-6), of which all but one had not been implicated previously. We show that the identified genes are predominantly expressed in brain tissue, and pathway analysis indicates the involvement of genes regulating cell development (MAGMA competitive P = 3.5 × 10^-6). Despite the well-known difference in twin-based heratiblity for intelligence in childhood (0.45) and adulthood (0.80), we show substantial genetic correlation (rg = 0.89, LD score regression P = 5.4 × 10^-29). These findings provide new insight into the genetic architecture of intelligence.

      And the title of the study is "Genome-wide association meta-analysis of 78,308 individuals identifies new loci and genes influencing human intelligence" which has nothing to do with the GP accusation (again)...

  3. A few technical comments by Michael+Woodhams · · Score: 5, Informative

    These results are from using SNP chips. To make a SNP chip, a sample of individuals from a population (in this case, humans of European descent) are sequenced, then the sequences are compared to find SNPs (single nucleotide polymorphism: i.e. a place where some individuals have one DNA base and others have a different one.) Then some hundreds of thousands of those SNPs are selected (we want something like an even spread of SNPs over the genome, and we want to chose SNPs which have a fairly high degree of polymorphism - we'd rather something which was 50:50 rather than 99:1.) A SNP chip is designed which when exposed to DNA from an individual will say yes/no for each SNP. (Scanning the paper, I see two of the SNP chips they used were UK BiLEVE Axiom array and the UK Biobank Axiom array which have over 820,000 SNPs each.)

    This has several consequences. One is that the SNP chip is of limited use for populations other than the one for which it was designed. Another is that seldom is the SNP on the chip directly related to the feature/quality (intelligence in this case) that we are trying to correlate with. Rather, the SNP which correlates positively with IQ is probably just nearby the genetic difference which matters. Because they are close, recombination (shuffling of the two genome copies you have, which happens in the production of gametes) is unlikely to separate them. Because they will occasionally get separated, the correlation of IQ with the SNP is going to be a little less strong than the correlation of IQ with the actual variant gene (allele). A SNP chip is less informative than a full genome sequence, but is much cheaper, and much easier to analyse.

    A final point is that genome wide association studies like this have in the past been plagued with false positives. When there are so many variables being tested (hundreds of thousands of SNPs on the SNP chip) some will strongly associate with your measured quality (IQ) by chance. This is even more so if you use sophisticated analyses which look for combinations of SNPs as predictors. I will provisionally accept that they've accounted for this correctly, as I lack the expertise to judge for myself.

    I work in a tangentially associated field (phylogenetics) so my knowledge has some professional basis, but is well short of that of an expert in the field.

    --
    Quattuor res in hoc mundo sanctae sunt: libri, liberi, libertas et liberalitas.
  4. Five Percent is the important number by gurps_npc · · Score: 5, Interesting

    ALL the genes put together had a total of 5% impact on Intelligence. That means an IQ of 105 vs 100. That is a minor effect.

    Worst of all, minor effects like this, are typical of false positives. That is, most scientific tests use a significance threshold of no more than 4%, which is one in 25. That means if you test 25 different random alcoholic drinks, one of them, by random chance, will be shown to cause a minor increase in intelligence. This would be a false positive.)

    And they did over 300 tests. So if they are using a 4% significance, that would be 4*3= 12 false positives.

    This article looks like the worst kind of fake science news. You know, the kind that a President would quote (Pick Trump/Obama, whichever your personal bias thinks would do that).

    --
    excitingthingstodo.blogspot.com
  5. Iodine is the US gap by mveloso · · Score: 4, Interesting

    Apparently iodine is the reason people today are marginally more intelligent than the were before.

    http://blogs.discovermagazine....

    That doesn't mean that genetics doesn't make a difference.

  6. Re:Match against questions! by SLi · · Score: 4, Insightful

    This "theory of multiple intelligences" is a quite popular narrative, but it's not empirically supported by studies. Rather, it seems that there is one "g factor", or general cognitive ability, that tends to explain quite well the "different kinds of intelligence". That is, any IQ test seems to be a good predictor of performance in any other IQ test, whether testing logical-mathematical, linguistic, spatial or some other "kind" of intelligence.