Space and time

David Reich, in his book,  made an important point that I noticed but did not emphasize. The plus variants for educational attainment are getting rarer at a rapid pace in Iceland and the US ( and probably all other developed countries), corresponding to a drop in IQ of about a point a generation – which is about what you would expect from heritability and known demographic patterns, something which has been known from before I was born.

Reich points out that it’s pretty hard to believe that selection A. couldn’t or B. just wouldn’t change IQ in different populations [ given tens of thousands of years], if it is changing things right in front of our eyes.  If selection had different effects on IQ in different eras, it almost certainly had different effects in different places.

Along this same line of thought, we may expect to see differences in IQ in past European populations, extrapolated from ancient DNA.

 

 

 

 

 

 

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116 Responses to Space and time

  1. magusjanus says:

    I have total ignorance on this subject, but I’m curious how much ancient DNA we can gather from specific time periods (like Phoenicians, or Athenian golden age, or Sumerian “black headed people”) such that we cold do said analysis and see the decline in IQ over course of a civilization? Is it hopeless, or is it something that’s possible if we dig up enough graves?

    Is ANYONE doing anything like this or along these lines?

    Also while at it, why not dig up graves of famous people like Gauss or Euler and see how they rank on the hits we currently have (also while at it try and settle Gauss’s paternity per your theory).

  2. Craken says:

    I wonder how many surprises this will offer up–types of findings that couldn’t be guessed at based on standard history. Maybe what looks like dysgenic decline in the late Roman empire was more a case of increasing exposure to lead pipes and vessels–or at least the exclusion of unleaded provincials from positions of power. Cremation was popular at key times/places in the ancient Mediterranean, sufficient to cause some major gaps in the genetic record. These gaps include the golden ages of both Greece and Rome.

    Researchers will have to be careful about sampling error, a challenge specific to each site.

    • Patrick Boyle says:

      I wouldn’t be too certain about attributing the decline in Rome to lead in the drinking water. First of all the dates are wrong. The aqueducts were started around 300 BC. The decline was at least a half millennium later. Second most of the water channels were not lead. And finally lead leaches out in acidic water and the main water sources for Rome were alkaline.

      A few years ago lead got in the municipal water supply around Detroit when they switched to an acidic water source. The existing lead feeder pipes started releasing their lead. All lead pipes in the US will soon be replaced. But for most water supplies lead does not get in the water because the water is mildly alkaline.

      • J says:

        Rome did not start declining around 800 BC. By that time it was hardly been founded. The leaching of lead from Flint’s pipes could have been prevented simply by the addition of a buffer. The digging up and replacing of old lead pipes is not necessary in Flint nor the whole US.

  3. Nebuchadnezzar II says:

    Would be interesting if we could compare G-factor PRS scores between historical hunter-gatherers and farmers across time. For instance, between the Neolithic farmers that spread agriculture in Europe and the Western Hunter Gatherers. Or a comparison between the Neolithic Iranians and AASI etc.

    Or perhaps even an analysis of what effect the earliest civilisations had on in-situ populations’ G factor scores, eg. compare scores from dynastic populations of the earliest civilised states of the world to their hunter-gatherer ancestors that lived in the same region thousands of years before.

    Could offer confirmation to your work in the 10,000 Year Explosion.

    • BB753 says:

      It stands to reason that a similar rise in IQ occurred in Europe after the Black Plague, which led to the Renaissance and the Industrial Age. The survivors got an IQ boost and better living conditions as a result of the culling. It’s been slowly downhill since the Victorian Age, as you point out. Though intellectual decay might be accelarating as we speak.

      • gcochran9 says:

        It does not: the Plague was pretty random.

        • owentt says:

          Nutrition improves IQ without changing the genes. All we need to do is administer a battery of tests to the young people growing up in the 1350s and 1360s in Western Europe to test the hypothesis.

          • TWS says:

            Nope, those born in the early sixties were the first generation with almost no, nutritional deficits. You can check my grandfather’s generation and find people with obvious evidence of nutritional issues. That generation took tests for the military. No need to go back to the fourteenth century.

        • Poor urban people were the most affected; poverty correlated with IQ. Richer people either had more immunity due to better nutrition or opportunity to hide from epidemic.

          • gcochran9 says:

            Not that much difference in incidence, while the correlation between wealth and intelligence isn’t that large. You certainly couldn’t have noticed the effect in a single bout of plague.

  4. jb says:

    I noticed that in the book too, and I was kind of shocked. He didn’t make a big deal of it (like I would have), but he didn’t have to go there at all, and yet he did. Reich gives no indication of being a badthinker, but maybe he is actually honest, at least internally?

  5. Smithie says:

    I don’t want to be disrespectful or sacrilegious, or anything, but someone get a pickaxe, shovel, and grinder. Meet me at the place where Wilhelm II is buried. We will wassail from one royal tomb to another, while collecting DNA samples to estimate royal IQs. Throw in Cromwell too, since his bones are in the same location as some others, and maybe add some of those French radicals, as well as Napoleon to round out the set.

    BTW, what do we know about where Genghis is buried, and the Chinese and Jap emperors? What is the best pick for a long dynasty? The House of Osman? And are the Inca royals too near the Equator?

    • athEIst says:

      Throw in Cromwell too, since his bones are in the same location as some others.

      Cromwell had himself buried in West Minister Abbey but Charles II had him dug up and hanged. His head stayed on a stake until 1685, his body was discarded

      • Smithie says:

        Makes sense. I guess one legend is that the bones of the kings were all transposed by Cromwell. Probably false, but we could test it.

    • I would be cautious about Genghis Khan. What if he rises from dead and takes his rightful place as sole master of the world?
      Btw, can you reconstruct Temujin’s genome given how numerous his descedants are?

      • Smithie says:

        That’s right. Genghis with modern tech could be kind of scary. Bigger empire, easier to maintain. A death in leadership might result in the generals just flying back. Or worse still, they could just decant another clone.

        • General Utility says:

          All is well, we’ll just bring Alexander, Napoleon, Qin Shi Huang, General Barca, Epaminondas, Yi Sun-sin, or a consensus genome thereof, and swiftly solve the matter. It won’t end badly!

  6. Jim says:

    The whole idea that there must be a universal constant that is the average genotypic cognitive level of the some 6500 different ethnicities in the world today and in the past for hundreds of thousands of years including small isolated populations such as Australian aborigines is utterly preposterous.

    • John says:

      Couldn’t agree more. The onus must be on those who believe “we are all the same under the skin”, to prove their case rather than the other way around. To the best of my knowledge none of them has ever even tried to do so. They just set your ‘universal constant’ as their comfortable, unthinking, unscientific, default, and carry on regardless. A stain on the world of science.

  7. jbbigf says:

    What are these “known demographic trends”? Idiocracy? Is there evidence, beyond the anecdotal, that high IQ has become non-adaptive? What about the possibility that modern medicine, and perhaps modern diet, makes it easier to survive with a higher load of random mutations?

    • gcochran9 says:

      Smarter women have fewer children: known for many years. Idiocracy is a riff on the Marching Morons, but Kornbluth was aware of the demographic facts.

    • krakonos says:

      It has been for a while and used to be even publicly broadcast in the past – one old weekly cinema news from early sixties.
      It was about state of university education and it stated that in the next generation, for university educated, proportion of children is going to decline by 20% due to low fertility. No further details provided.

      During that time our country was a full blown communist regime with omnipresent censorship and all news had to be approved before sent out. Communists had to be concerned about it.

  8. Dave Chamberlin says:

    “If selection for IQ had different effects in different eras it most certainly had different effects in different places.”

    The horrible terrible forbidden truth about racism as it pertains to variation in IQ between groups isn’t nearly as bad as drama queens make it out to be. It makes absolutely no sense to proclaim everybody from population A is intellectually superior to everybody from population B if there is a shifted bell shape curve of one standard deviation, 15 points between the two groups as measured by intelligence tests. Only a stupid mean spirited person could possibly think that. However there is a HUGE increase in in high IQ people in population A, which completely accounts for why there is almost a perfect correlation between high average IQ scores and modern prosperity.

    The question of just how fast can evolution push a population to a higher or lower IQ isn,t a huge mystery thanks to the work of Greg Cochran in his work studying the Ashkenazi Jews. It is all laid out in one chapter of his book The10,000 Year Explosion. This population is absolutely unique in human history not just because this population had a huge reward for increased intelligence but also it remained isolated while living amoung a larger population. The numbers are remarkable in their clarity. This population of approximately 11 million or one in 770 humans has won 1 out of 5 Nobel prizes. They had to evolve a higher intelligence since the Renaissance or they would have contributed to that as well, but they didn’t.

    I don,t know how much clearer things can be, but it doesn’t matter. The big bugaboo that these thoughts are mean spirited and racist and need to be censored will continue. Truth isn’t mean and it shouldn’t be hidden. It is overwhelmingly likely that we shall genetically engineer smarter humans within a century and all our present day beliefs censoring variations between groups in intelligence will seem quaint and ignorant.

  9. Cpluskx says:

    I would like to see the IQ’s of:
    Sumerians, Ancient Egypt, Yamnaya, Minoans, Bronze Age Anatolians, Babylon, Etruscans, Carthaginians, Rome (the city(Republic)), Ancient Greece (especially Athens), early Islamic Golden Age MENA, Huguenots.
    Current day:
    Parsis, Maronites.

  10. There is also the decrease in violence centered in northern Europe – except when we all got organised and went to other places in groups, of course – also tracking the Hajnal Line pretty well. There may be something related to delaying gratification, allowing the other clan to pay you money for killings, rather than just leaping into their village, screaming. This also widens the circle of who you consider Our Tribe, which may come from the northern Europeans being the first people to take the Catholic Church’s command not to marry cousins seriously. The Sicilians certainly didn’t. This meant A) less intra-tribal violence and B) getting along with larger groups for war bands and trade. Both of these look like they have genetic underpinnings: delay, cooperativeness.

  11. Eponymous says:

    How concerned should we be that GWAS estimated on modern populations won’t explain much variance in earlier populations? Obviously is a concern at some point, but would that make much difference looking at people 2-4kya?

    • I would expect earlier populations to have worse environments… so the mean would be lower and the variance higher?

      Though IQ boosting alleles probably boost it regardless of environment, they’ll just be more effective in better environments.

      • Some of alleles might improve IQ in some environments by increasing immunity to some pathogens; and change direction after pathogens get cleansed of.

      • Eponymous says:

        I’m not concerned about differences in the environment. I’m concerned that a PRS estimated from modern people won’t pick up the genetic variants relevant for explaining differences with past populations. For example, suppose there’s a +IQ variant that has frequency 30% in an ancient pop but is at 95% today. A PRS on a modern pop wouldn’t find it. Another issue is that a PRS probably weights lots of non-causal variants that are associated with causal variants through LD patterns. But these LD patterns will change over time. My question is how much these concerns will degrade accuracy over historical timescales.

  12. Lior says:

    Greg,would you consider doing an open thread taking questions ocuassionaly? ,or maybe doing a Q&A of questions taken beforehand next time your on James Miller’s podcast.

    • Greg, if you take questions I have one – what is the potential IQ gain from optimising everyone’s environment, so it becomes 100% heritable rather than 80%? Could we boost the mean IQ by 3-6 points by doing this?

      • Lot says:

        A big gain in Africa and India, not much in the USA or Europe or NE Asia.

        • I’m aware it’s “not much” – certainly far less than a standard deviation. But I want to know how much is not much.

          Even a 3 point gain would lead to significantly less societal dysfunction by raising the IQ of the lowest, and such gains would likely be concentrated among the left hand side of the bell curve. It might be a 6 point gain for them. Given the negative correlation between IQ and fertility, even a small gain would make current fertility less dysgenic, by raising the lowest scorers and so suppressing their fertility.

      • Phille says:

        The missing 20% aren’t necessarily things you can change. Might just be noise in the developmental process of the embryo or something. That being said, optimising the environment might raise mean IQ without increasing heritability much. There is still iodine deficiency in Europe for example.

        • savantissimo says:

          I suppose nothing can increase heritability “much” because it’s so high already, but completely equalizing environment can only mean that the remaining remaining variation is either inborn or random.

  13. gregor says:

    A fairly recent Twitter exchange with Molyneux and Taleb:

    Stefan Molyneux: “If we had been allowed to talk about race and IQ, the invasion of Iraq would have never occurred, because no one would have been under the illusion that a Jeffersonian Republic was going to emerge from a population with an IQ in the 80s. Opposing Science got >500K people killed.”

    Nassim Taleb: “Mesopotamia

    Invented Metallurgy, Agriculture, Writing, Sailing, theWheel, Chemisty, Pharma, Astronomy, LAW,(co)algebra, Algor, Calendar, Maps, Metrics…

    Maintained techno superiority for 4600/5000y of history.

    So fraudster @stefanmolyneux now arbiter of their inferior “IQ”. ”

    In terms of cultural achievement, Mesopotamia (and Egypt) had the early lead. Later Greece and Rome were dominant. Then later NW Europe. The fertile crescent was particularly suited to be the birthplace of civilization.

    • JerryC says:

      Mesopotamia was great, in its time. But what have they done for me lately?

    • gcochran9 says:

      Iraqis test low, and they certainly act it. Taleb’s talking through his hat. Not for the first time.

    • Lowe says:

      So Taleb’s reply is to point at accomplishments from literally thousands of years ago. That’s pathetic.

      • dearieme says:

        It’s also anti-Cherokee. Senator Warren should be alerted.

      • Toddy Cat says:

        Taleb is a smart guy who is right a good deal of the time, but his titanic ego makes it impossible for him to admit that he’s ever wrong, so he tends to back himself into corners sometimes – like on the IQ issue.

        • Aldon says:

          He’s a Sandmonkey who hates other Sandmonkeys and LARPs as a Greco-Roman since he’s ashamed of his actual heritage (which is largely that of the Muslims in the Levant). No better than Basketball-Americans saying they’re Egyptians and Hebrews.

      • J says:

        Mesopotamia was depopulated by the Mongols. The current population is mostly Bedouin, unrelated to the people living in the area five thousand years ago. Even Saddam Hussein had tribal marks. Taleb should know.

        • gcochran9 says:

          There certainly was depopulation from the Mongol conquest, and some Bedouinization, but I don’ know just how much population continuity there is.

          • mtkennedy21 says:

            The Greeks are mostly unrelated to the Geeks of classical Athens.

            • gcochran9 says:

              You’re wrong. We have the ancient DNA to prove it. The Greeks have picked up a little Slav, that’s about it.

              • J says:

                The IQ of a population is not a fixed quantity but varies. Two thousand five hundred years are more than enough to lose ten or twenty points. And the Greeks are still losing IQ, like all contemporary Western populations.

              • Greeks - Ancient and Modern says:

                Assuming Slavic populations are anything like the earliest sample we have from 600 AD (in Bohemia) and assuming Greeks of late Antiquity anything like Mycenaeans, then you probably need replacement of half Slavic, about to get those Greeks that fit on that cline.

                But not all Greeks do – even mainland Greeks don’t fit cleanly between Mycenaeans and the Slavic sample from Bohemia. Many are more clinal between Mycenaean and present day Anatolia, and Greek communities in Anatolia today are of course similar to Turkish people (with less Turkic admixture) and not mainland Greeks.

                Of course, Mycenaeans may not be representative of classical Greeks – almost certainly not, as the samples are from the Peloponnese, and the actual luminaries were mostly Ionians from the Anatolian coast about a thousand years later.

                Replacement could be more significant than this, depending on how related invading populations already were to Greeks (you’d need much more Thracian than Slavic Bohemia to achieve the same total change).

            • feryaj8755 says:

              The Greeks weren’t Germans and Aristotle looked down upon north Europeans as less intelligent.

      • gregor says:

        Yeah, it’s not even clear that the early phases of civilization require particularly high intelligence. We know the Mayans independently came up with calendars and writing and such. Were they geniuses? Doesn’t seem like it. Their “Classic Period” ended in 900 AD which is pretty recent. And there are still unmixed Mayans in Guatemala.

    • Aldon says:

      Just about every example he said can be debunked by Wikipedia, demographics, and him being a LARPer.

      Metallurgy

      Serbia at worst is contemporary with Mespotamia in discovering metallurgy.

      Agriculture

      Levant.

      Writing

      China, Greece, and Romania all have archaic writing.

      Sailing

      Polynesians.

      theWheel

      Caucasus.

      Chemisty

      Greek.

      pharmaceutical

      Egypt had at worst had some at the same time.

      astronomy

      Goseck circle in Germany and of course Stonehenge.

      LAW

      Egypt.

      calender

      Scotland.

      Taleb being a Levantine (like the Muslims he denies his ties to him so he can pretend he belongs to the same civilizations as the Greeks and Romans) makes him not belong to Mesptomanian civilization.

      • The Course of History says:

        Writing is probably fair to give to them – part of issue mainly being that writing allows you to write down lists of your innovations, falsely suggesting to folk like Taleb who have no understanding of or interest in archaeology (as an alternative to written records) that these areas were the first to achieve innovations.

        Technological progress has tended to be more even across time, against proscriptions both that northerners were “held back” until recently (no, they just weren’t systematically greater at innovation and still probably aren’t, net of circumstances), nor that southerners were dominant.

        Today southerners like Tabeb generally have more difficulty accepting a modern paradigm that Europe (and other pre-literate regions) were neither useless eternal receiver of innovations and migrations, nor dominant centre of the world, and the idea that the dominance that they believe their cultures to have was probably a bit of a false impression from biased evidence. Chinese have some similar issues with the passing of the paramountcy of their own civilization on the world stage, though that was much briefer (perhaps from the fall of Rome to the Italian Renaissance at most, and that’s if we very charitably wave aside advancement under Islam and the Byzantines).

        • Eugine Nier says:

          Writing is probably fair to give to them – part of issue mainly being that writing allows you to write down lists of your innovations,

          It also makes it easier to preserve your knowledge, and to make inventions, e.g., astronomy is much easier if you can record the positions of planets at different times.

      • Eugine Nier says:

        Seriously, you sound like a classic WE WAZ KANGS. No aligning some stones with the solstice is not the same as calculating the position of planets.

    • akarlin says:

      It’s rather hard to accomplish much when you’re living in small bands, while people located in more suitable climes have developed agriculture, and consequently, cities and literate castes. However, the general pattern has been that as the frontiers of civilization expanded to colder climes, it was the former barbarians who took the lead in development.

      • Frontiers says:

        Also true when expanding into Southern China, and Persian Islam into the Turan. Generic catch up and regression to the mean is a thing.

        You could probably argue the expansion of Islam and then the Islamic Golden Age back into the core was also such a “barbarians taking the lead in development” (certainly not all contributions from Persia), although ultimately that path was less competitive.

  14. sterling sorbet says:

    I’m betting on the transposable elements as a possible explanation.

  15. dux.ie says:

    The relationships between the EastAsian and European clusters are fairly orthogonal, each dominating only one of the dimensions of CCR5 Delta32 and ADH1B. The relationship between IQdb and ADH1B2 allele freq provides the third complementary primary dimension to the above chart on IQdb vs CCR5 Delta32. The European clusters have zero or minute ADH1B2 and are clustered on the extreme left and the vertical spreads are because of different CCR5 Delta32 frequency, similar to that for the EastAsian clusters in the above plot. In both plots it is apparent that Ashkenazis are outliers as it possesses both CCR5 Delta32 and ADH1B*2 mutations which might favour cognition.

    IQdb=+14.07*ADH1B2+92.87; #n=44; Rsq=0.272; p=0.000284 *** (VVSig)

    IQdb=+137.6*Delta32+78.83; #n=67; Rsq=0.281; p=3.937e-06 *** (VVSig)

    Unable to upload chart. 😦

    The path Ashkenazis taken to achieve that might be explained from the historical dispersion of the ancient ADH1B haplogroup H1 and mutations at various stages H2, H3, H4, H5, H6 and H7, with respect to MiddleEast, Europe and EastAsia.

    • dux.ie says:

      https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3722864/pdf/nihms474006.pdf

      The haplogroups H5 and H6, both with the derived ADH1B*48His allele, appear restricted to the Middle East and East Asia, respectively. The positively selected H7 is derived from H6 by a new regulatory region variant defining SNP rs3811801 restricted to East Asia.

      The frequency of the derived allele of this variant (Arg48His rs1229984) is common to high (>25%) in West Asia and East Asia, but infrequent to absent in the rest of the world, including the regions between West Asia and East Asia. In South Asia, the ADH1B*48His allele is almost absent. (This might explain the average IQ gap between India and China.) The high frequency of the ADH1B*48His variant in many East Asian populations is most likely the result of natural selection. A variant in the regulatory region of ADH1B, the derived allele at rs3811801, is possibly responsible for the selection and the particular functional association in East Asia.

      H5 occurs mainly in the Middle East, while the evolutionarily derived H6 and H7 are mainly in East Asia. Only a very few individuals among the Chuvash, Adygei, and Ashkenazi Jews belong to H7, which might have been introduced from the East very recently, as these populations lie along historic trade routes, e.g., the Silk Road. The low STRP diversity of these few H7 individuals in the West also supports the recent arrival of the haplogroup from East Asia.

      H1 is as old as the whole human population. The age of H5 is very close to the most accepted time of the “Out of Africa” event and it appears to have been born in the Middle East, the geographic location for the first modern human emergence “out of Africa”. The youngest haplogroup is H7 with an expansion age of only around 1,600 to 4,000 years.

      ADH1B| KBP
      H1 | 185.4±25.6
      H2 | 4.1±2.5
      H3 | 32.7±9.1
      H4 | 135.8±28.5
      H5 | 66.7±16.9 (yHg CT split to F? Later F to JK at 45 KBP? J MiddleEastern, K CentralAsian)
      H6 | 21.4±8.6 (yHg K split to NO? yHg NO Asian (exclude Siberian Q and IndoEuropean R))
      H7 | 2.8±1.2 (yHg O split to O1,O2,O3 EastAsian? known Chinese history)

      The origin of the CCR5 Delta32 mutation had been estimated to 700 to 125000 BP, time before the migration of the Jews to central Europe.

      https://www.eeb.ucla.edu/Faculty/Novembre/GalvaniNovembreMicInf2005.pdf

      Ancient Jews had the ADH1B48His mutation which was absent from the European and thru admixture some lost the active CCR5 to have the Delta32 mutation. Differences between Jewish subgroups like Askenazis, Sephardics and Mizrahims could be explained from their ascestral distances from the CCR5 Delta32 origin in Northern Europe. A stark contrast is the Roma who originated from India though might gain the CCR5 Delta32 thru admixture but without the ADH1B48His mutation they only obtained “street smart”.

      It is interesting to speculate whether Zuckerberg and “tiger mum” Amy Chua have the innate instinctive desires to push the next level as shown by the empirical trends of cognition evolution with strong verbal and spatial IQs.

  16. These ancient genomes surely be quite damaged. How are you going to adjust for this?
    Take many samples so damages would average out?

  17. adreadline says:

    ”…something which has been known from before I was born”

    Which was during a chilly evening in 1923, just before the British winter started…

    Wait. I’m thinking of another physicist who has lately been interested in genetics.

  18. S3 says:

    Startup idea: dating app which lets you see the other side’s IQ, ideally their parents and siblings IQ too. Somebody with better Silicon Valley connections than me should start working on this ASAP. For once the Valley could be saving the world for real!

  19. Pingback: Better Human Capital | The Z Blog

  20. little spoon says:

    I suspect that iq is now gradually declining within racial groups in most developed countries, but I also suspect that iq is becoming increasingly more stratified in many developed countries. Meaning that the likelihood of iq 140 people having high iq offspring may be rising due to selective mating based on education levels. Much of the affluent classes place high value on children who do well in school these days and they seem to understand that the way to produce such children is to marry someone who themselves is bright.

    • gcochran9 says:

      I don’t think it’s very common.

      • SuperMario says:

        That’s because 140 IQ isn’t common in the first place.

        Also, in that recent Norwegian study it was found that higher IQ parents tended to have MORE children on average than the lower IQ parents (I guess it’s 2 kiddos vs. 1, but the fact remains).

        The kink in little spoon’s theory, however, is that the offspring of high IQ parents also showed the dysgenic trend; in other words, they had lower IQ than their own parents.

  21. j2 says:

    This is off-the-line, but I posed a question to a commenter in the Unz Review and he replied
    “Go to Greg Cochran’s blog and ask him. He answers questions.”
    So, I pose the question here:
    Polygenic score in GWAS is additive. Do you think it will explain genetic determination of traits to a nearly complete degree if studies use more samples? Seems that GWAS for height explains only 26.4% of height variation so far.
    https://www.biorxiv.org/content/10.1101/274654v2
    How much do you think could be nonadditive genetic contribution?
    Obviously the relation is not fully additive, and though for diagnostic purposes an additive polygenic score may well suffice, for understanding the phenomenon it should be expressed as a sum of additive and nonadditive terms. To demonstrate that it is not additive it is enough to consider two gene alleles, which both are required for some functionality. If so, then the combination is a product of occurances of these alleles, not a sum.

  22. Eponymous says:

    A related question: can you look at evidence for recent selection around identified +IQ/EA variants to estimate the strength of selection for IQ at various points in time? Then you can construct a time series by integrating over the implied derivative.

    • J says:

      That would be interesting. One problem would be that some variants are quite recent, see Ashkenazi population. And probably there are several different variants for IQ, like there are different variants for white skin between European and North Asian population, like variants for blond hair between Europeans and Melanesians.

    • dux.ie says:

      From https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3722864/pdf/nihms474006.pdf
      the ADH1B haplotype H7 appeared in China about 2 KBP. That is about the time the Han Dynasty started the imperial court exam for selecting court officials with high IQ. Nobody want to notice that. Many claimed that the H7 explosion was due to rice cultivation which is oddly goes back at least 7 K years.

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