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January 17, 2012 / JayMan

IQ Ceilings?

I had promised a couple of posts to bring those not necessarily familiar with HBD (i.e., Human BioDiversity) up to speed, but as I’ve not been getting around to those transitional posts, I’ve decided to skip that step and go on ahead.  So here is my first semi-original contribution to the world of HBD.  I’m going to take a look at the global distribution of average IQ scores in light of what we know about recent human evolution:

The two general things one notices is that first, average IQ scores cluster by race; that is European peoples all have average IQ scores around 100, Black Africans all around 70, Native Americans in the 80s, etc.

505a6ddc48eve001(IMPORTANT DISCLAIMER: It’s very important to note, for those who aren’t familiar with the statistical nature of IQ and other biological traits, is that in most every population, you have individuals at all levels of IQ; that is, there are plenty of smart Africans and plenty of not so smart Europeans, for example, even though the group averages are different.  By no means is every last European smarter than every last African.  A good analogy is height among the sexes.  Men are, on average, taller than women.  But that surely doesn’t mean that there aren’t tall women or that there aren’t short men, as one can clearly see here. Rather, the average of a trait tells you something about the frequency of that trait in a given population, as for example, there are many more men than women at a height of 6’2″, just as there are many more women than men at a height of 5’2″.  Group averages don’t necessarily tell you anything about a given individual.)

The second thing one notices is that average IQ increases with latitude. The traditional explanation, advanced by Richard Lynn and J. Philippe Rushton, is that racial differences in IQ are very ancient and go back to when humans migrated out of Africa into Eurasia and experienced the two previous ice ages.   The theory goes that cold winters select for higher intelligence as these conditions present challenges to survival not found in the tropics (such as storing food, keeping warm, or hunting big game).  As such, Eurasians evolved higher IQs than Africans to cope with these conditions.

(A note on the low average IQ of some groups, like sub-Saharan Africans and the Australian Aborigines: those scores are not in error. Multiple lines of evidence confirm these low scores, especially for Africans.  You may have heard that IQs ≤ 70 signifies mental retardation, but that is not exactly the case.  That number was selected as a somewhat arbitrary marker of retardation and is only obliquely related to true retardation in the sense that most people think of it.)

However, this theory is problematic for several reasons.  For one, the most northerly group, the Inuit, do not have the highest average IQ (though it is higher than most peoples further south).   Going further south in the New World, the Native North Americans do not have IQs comparable to Europeans, despite having lived in very similar climatic conditions.  Additionally, although the average IQ of Mongolia is listed as “unknown” on the map, IQ data from Mongolians living in China find that their average IQ is about 100, slightly lower than the Han Chinese who live further south.

As well, we have Gregory Cochran’s & Henry Harpending’s 2010 book The 10,000 Year Explosion: How Civilization Accelerated Human Evolution which demonstrated that the pace of human evolution has in fact been speeding up and has been since the advent of agriculture and the rise of civilization.  This suggests that much—or perhaps all—of the global distribution in IQ is recent, within the last few millennia or less.  To see this, let’s take a closer look at Europe (click to enlarge):

This is a map that I have made of the average IQ of the European nations based on data assembled by Richard Lynn and Tatu Vanhanen (also here) as well data from the PISA test as complied by A Reluctant Apostate and hbd* chick.

As we can see, there is considerable variation in the average IQ of the different parts of Europe, even within nations, as we see in the U.K., Spain, and Italy.  It is not at all true that the average IQ of all European populations is 100 (indeed that number is based on the average score of White British), because several populations score below it.  In general, we see a decline in the south and southeast.  But also standing out as distinctly low is Ireland (Lithuania’s score is probably spurious due to bad sampling).

But more interestingly, there seems to be a relationship between modern IQ levels and fairly recent history in Europe, since the Middle Ages, as we see here:

This is a map of the Hajnal line, which is the red line seen here.  West of this line, we have a unique pattern of marriage, as Wikipedia states:

West of this line, the average age of women at first marriage was 24 or more, men 26, spouses were relatively close in age, and 10% or more of adults never married. East of the line, the mean age of both sexes at marriage was earlier, spousal age disparity was greater and marriage more nearly universal.

The blue lines mark areas west of the Hajnal line where nuptiality was high and the above pattern didn’t necessarily hold.

But we see something more interesting when we overlay the Hajnal line with my map of European IQ, as hbd* chick did:

It can be seen that aside from Finland, these exempt areas correspond to the regions of lowered average IQ in Western Europe.

Hbd* chick has just written a glorious summary of why this may be so:

 the populations behind the hajnal line (i.e. the core of europe) are characterized by:

– late marriages (present since at least the early medieval period)
– small family sizes (nuclear or stem families versus extended families; also present since at least the early medieval period)
– higher average iqs, in general, than populations in the periphery of europe (see map)
– strong future time orientation, strong societal collectivism, strong preference for rules and order (Ordnung!), strong drive to succeed
– being more civic than populations in the periphery of europe

why?

well, maybe it’s just ’cause these populations are mostly germanic, or at least had a strong-ish germanic presence in their territory at some time in the past. maybe this is just an example of ice peoples who evolved high iqs and a lot of other neat traits ’cause they survived for a long time in adverse conditions.

but’s it’s hard to ignore how the Type A Personality areas of europe coincide with the hajnal line. at least, i find it hard to ignore. what happened behind the hajnal line?

at the risk of repeating myself (is there an echo in here?), what happened behind the hajnal line starting in the early medieval period was:

– changes in mating patterns (thanks to the church) from close relative marriage to more distant marriages, thus breaking down clans and tribes
– changes in the economic structure from whatever the h*ll went before (i have no idea) to manorialism
– changes in family structures (thanks to both the increased outbreeding and manorialism) from extended families to smaller nuclear or stem families

all of these would’ve changed the selection pressures on the populations in the areas where these practices were adopted.

A look at Italy illustrates what hbd* chick is talking about.  Here’s a map made by M.G.:

This is a map of consanguinity—that is, the rate of cousin marriage in Italy during the early 20th century.  This map shows that Southern Italians are fairly inbred (no, it’s not just Appalachia—more on that in a later post).  What’s more fascinating is that this map corresponds very well to my map of the average IQ of the various Italian provinces (and a whole host of other things, see M.G.’s blog). Italian stereotypes notwithstanding, especially of southerners, (including unfortunate and tragic demonstrations of Italian incompetence such as the recent cruise ship disaster), this shows the impact of more recent history on the evolution of Europeans.

What I found fascinating however is that people east of the Hajnal line still managed to evolve high IQs, such as the northern Slavs and the Finns.  People in this part of the world lived in a family system that was vastly different than that of westerners, as hbd* chick discusses here.  This caused Easterners to go down a considerably different social and political trajectory than did Westerners, and the system found in Eastern Europe was common in the rest of Eurasia going as far east as China.  This is displayed geographically here:

http://www.scribd.com/doc/72270658/Todd-s-Family-Systems-Map-1500-1900

However, despite these different systems, Easterners still managed to evolve IQs as high as Westerners.  Perhaps the IQ differences were pre-existing in the various populations, and I believe they most likely were—to an extent.  But one cannot escape certain recent historical correlates with modern average IQ levels.  For example, most of Southeastern Europe was dominated by the Byzantine Empire and then later the Turks.  One has to wonder if centuries of Muslim domination (and perhaps Muslim family structures) have had something to do with the lowered IQs of SE Europeans.

In any case, despite all this evidence for the recent evolution of modern IQ levels, there are the facts that average IQs cluster by race and correlate strongly with latitude (and skin color, but that’s not important at the moment).  If IQs reached their modern levels due to the fairly capricious events of history, then why are they not more haphazard across racial groups?  Why the consistency?  Perhaps this is evidence for a prehistoric origin.  Or perhaps this is result of several factors acting together to produce this effect, which is what I propose.

What if the reason that average IQ correlates with latitude is because climate imposes a ceiling on average IQ, not necessarily selects for a particular IQ level?  There is some evidence that head and brain size faced biological constraints in the tropics, due the problem of overheating.  And indeed, average head size increases with latitude, as can be seen here on this map of the average cranial capacities of indigenous populations:

Human variation in cranial capacity. Black, 1,450 cc and over; checkerboard, 1,400-49 cc; crosshatching, 1,350-99 cc; horizontal striping, 1,300-49 cc; diagonal striping, 1,250-99 cc; dots, 1,200-49 cc; white areas, under 1,200 cc (Beals et al., 1984)

Head size (and hence brain size) does indeed correlate with IQ, both between individuals and between groups, but it’s not a perfect correlation.  Far northerners, such the Inuit, have the largest heads (and largest brains) but not necessarily the highest IQs (as well, peoples with the smallest heads don’t necessarily have the lowest IQs, but as one can see from comparing this map to the first, the pattern is fairly solid overall).

Especially interesting are the Native Americans.  All Native Americans descend from Asians that crossed the Bering land bridge into the Americas.  Hence, all have had to  have been fairly cold-adapted people.  But Natives that hail from the American tropics seem to have regressed a bit in terms of head size and average IQ (as well as evolved darker skin).  I propose in that the tropics, the ceiling on average IQ is lower (not necessarily maximum individual IQ, as there are plenty of smart individuals who originate from tropical climates).  This may be due in part  to physiological constraints (heat stress), but also survivability.  Tropical living is overall easier than living in temperate and polar climates (in pre-modern times anyway, when we didn’t have the modern conveniences that makes winter living more bearable), since for one, food is typically available all year around.  Being exceptionally smart is not as much of a reproductive advantage (especially facing tropical diseases); or perhaps more accurately, being not very smart is not that much of a disadvantage.

Big brains come with drawbacks.  For one, larger heads make giving birth more difficult.  As well, brains are very metabolically expensive (your brain consumes about 25% of your resting calories).  Larger brains only make sense evolutionarily when these drawbacks are outweighed by the advantage increased intelligence affords.

Populations in different latitudes thus face different limits on how far they can advance in average IQ, both because of limits on those at the top, as mentioned, and because of the level of relaxation of limits on the bottom.  That is, even if the smartest members of society reproduce well, the society’s average IQ will not increase if the least intelligent individuals also reproduce as much.

For long periods of time in Europe, there was a strong limit on the bottom.  The highly stratified nature of European society meant that the poorest (and on average, least intelligent) individuals faced poor prospects for surviving and raising children.  Over time, that meant that almost all people in many European societies were descended primarily from the upper classes (which is why when many of you trace your ancestry back that far, you often find European nobility/royalty).

This is, by the way, an example of how I think this ceiling effect can operate: perhaps in lower latitudes, the constraints on those on the bottom were not as tight, and less intelligent people were able to survive and reproduce more.

However, the important point—and the part that I think has been missing from the puzzle—is that regardless of the ceiling given by climate and geography, it is not a given that a population will evolve to reach that ceiling.  Looking at Europe again, we can see that the Irish have a lower mean IQ than the rest of the inhabitants of the British Isles; they have not reached their region’s ceiling.  I contend that in pre-civilized times, no Europeans did.  The earliest Europeans (or perhaps more accurately, the earliest farmers) probably did not have the equivalent of an average IQ of 100 (though it was probably higher than modern Africans).   Instead, I contend that their IQs increased to their current levels through the effects of civilization, mostly during the Middle Ages, as described by hbd* chick’s hypothesis.

Over in Asia and the Americas, the same phenomenon likely applied.  The early Chinese/Koreans/Japanese probably did not have the same average IQs as their modern counterparts.  Their average IQs may have instead been more like the Mongolians or the Inuit, and only reached their modern levels through the effects of millennia of civilization (and likely heavy attrition in the lower classes).

So it seems that different latitudinal regions have different ceilings.  Broadly speaking, the IQ ceiling in sub-Saharan Africa is lower than it is North Africa, the Middle East, and South Asia, which is in turn lower than it is in Europe and Northern Asia.  Average IQ is allowed to rise somewhat in these northern regions, as the Mongolians, Siberians, Inuit, and Native Americans demonstrate. Civilization then takes it “all the way”.

Even in Africa, farming/herding Africans, such as the Bantu and Nilotic groups, seem to have higher average IQs (≈ 70) than the more primitive hunter-gatherers like the rainforest Pygmies or the Khoisan (≈54).  The evolutionary/societal changes brought about by farming (e.g., population growth), as well as tools/ideas acquired through outside trade, allowed various Bantu groups to at times form regionally powerful empires in Africa.  The fact that many relatively unrelated groups, such as the Bantu and Nilotic peoples, have the same low (by Western standards) average IQ (70) indicates the rather low IQ ceiling there.

Another interesting fact is that it seems that the global average IQ ceiling may be 100.  While East Asians are noted as having an average IQ of 105, their mental profiles (along with everyone along the Pacific Rim, from Mongolians, Inuit, Native Americans, and Australian Aborigines) is such that their visuospatial reasoning is stronger than their verbal reasoning.  This may be because the plain, featureless terrain of the Asian interior may have selected for better navigational ability, or perhaps these abilities developed over time considering that these people have had the longest migration distance out of Africa (or both).  In any case, the average verbal IQ of East Asians is around 100, whereas their visuospaitual IQ is about 109-110 (which averages to 105).  Could it be that, for whatever reason, average verbal IQ peaks at 100 globally?  (It is verbal reasoning that correlates most strongly to most of the life success measures in the modern world.)

Indeed, the only group to exceed an average verbal IQ of about 100 are the Ashkenazi Jews, who seemed to have evolved an average IQ of 110 (which is strongest in verbal and mathematic ability but weaker in visuospatial ability) during the middle ages in Europe.  But the interesting fact about the Ashkenazim is that they did not evolve this high IQ in isolation, but by living among gentile Europeans.  As the Europeans Jews were always a minority group in a larger population, they were free to specialize in cognitive occupations (or more accurately, forced to specialize, since they were often barred from many occupations) in a way no other population could (because every other society needed laborers, farmers and other people do the grunt work).  This may have allowed them to break through the ceiling imposed on all other peoples.  But even this may have come at a price, because the mutations that lend themselves to Ashkenazi intelligence came with the side-effect of genetic diseases.  This could be a result of the necessary inbreeding that Jews practiced based on their restrictions on marriage outside the group; the high levels of exogamy among other Europeans may have distributed deleterious mutations rather than allow them to accumulate as they seem to have done among the Ashkenazim.

Our friend Occam’s Razor leads one to prefer explanations that are as simple as we make them, but no simpler.

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32 Comments

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  1. hbd chick / Jan 17 2012 9:08 PM

    iq ceilings make a LOT of sense — esp. how expensive the brain is in a hot climate. maybe it’s just not possible to get an average of ca. 90 or above when you live on or near the equator.

    you said: “Perhaps the IQ differences were pre-existing in the various populations, and I believe they most likely were—to an extent.”

    i was thinking along the same lines, too, and that the selection pressure i was talking about (from the medieval period) just sorta tweaked the germanic iqs a little higher. like you say, it’s interesting that the finnish iq is so high even though they’re on the ‘wrong’ side of the hajnal line. (or does that high average iq score reflect all the swedes, i.e. germanic peoples, in finland? that thought crossed my mind. dunno.)

    your scenario of south american indians losing iq points is not far out at all. you saw this post by greg cochran, yes?

  2. M.G. / Jan 19 2012 6:08 PM

    This is a compelling presentation of evidence, especially the IQ ceiling by latitude + survival-of-the-smartest in Malthusian Europe. Still, I don’t quite know how to think of the ‘ceiling’. Is it something natural selection has sort of programmed into us, like height or life expectancy? i.e. the well-fed, healthy Dutch have topped out at 6′ average, but the equally well-fed, healthy Japanese have topped out at 5’8″ average, and neither are going to get any taller? When genetic engineering (in the sense of fiddling around with ourselves in the petri dish) becomes accessible and cheap, will we be able to engineer ourselves to ‘break’ these ceilings nature has imposed on us? If so, what will such a world look like?

  3. hbd chick / Jan 21 2012 6:12 PM

    coulda sworn i left a comment here the other day, but i guess it didn’t work. let’s try it again! what i said was:

    iq ceilings make a LOT of sense — esp. how expensive the brain is in a hot climate. maybe it’s just not possible to get an average of 90 or above when you live on or near the equator.

    you said: “Perhaps the IQ differences were pre-existing in the various populations, and I believe they most likely were—to an extent.”

    i was thinking along the same lines, too, and that the selection pressure i was talking about (from the medieval period) just sorta tweaked the germanic iqs a little higher. like you say, it’s interesting that the finnish iq is so high. (or does that high average iq score reflect all the swedes, i.e. germanic peoples, in finland? that thought crossed my mind. dunno.)

    your scenario of south american indians losing iq points is not far out at all. you saw this post by greg cochran, yes?

  4. hbd chick / Jan 21 2012 6:20 PM

    @m.g. – “Still, I don’t quite know how to think of the ‘ceiling’. Is it something natural selection has sort of programmed into us, like height or life expectancy?”

    well, it comes down to how much energy can one afford to spend on any particular feature (brain, height, life expectancy) given the environmental conditions (and that could include social environment) one finds onself in. nature isn’t going to spend more energy on any organism than absolutely necessary to procreate (which is all any organism is “required” to do).

    if you can procreate sucessfully in your environment with an iq of 80, then that’s great. natural selection will let you get by with that. but if your conditions require you to have a 100 iq at minimum, no one with less will survive — they’ll be weeded out (natural selection).

    but no organism is going to expend more energy than needed in order to survive and reproduce. you’d probably just be putting yourself in a disadvantageous position compared to your competitors (i.e. expending more energy than they) — and it’s all about outcompeting the competitors.

  5. JayMan / Jan 21 2012 11:30 PM

    @M.G.:

    hbd chick has got the basic gist. Different climates, I think, set an upper limit on how high average IQ can get thanks to constraints on brain size and other factors, as well as how severely lower IQ people are culled from the population. For example, even if higher IQ individuals gain enough of a reproductive advantage to justify their larger/hungrier brains, if the lower IQ individuals can still get by (say by living in a tribal society where they can mooch off the smarter members), the average IQ will still be limited because the less intelligent people will drag down the average (not to mention mix their low-IQ alleles into the gene pool).

    I think I should have also stated that I believe that climate (and the societal/technological level in that climate) sets an average IQ floor as well. For example, all far northern populations have an average IQ of at least 90, so it’s safe to say that that’s likely the minimum average IQ of a population can have and survive there. I believe that there is a little wiggle room between the minimum and maximum IQ in a given climate, as we see in say Africa between the Bushmen and the more advance Africans. It appears that it takes things like agriculture and civilization to fully exploit the potential IQ of a region, which seems to be what happened to Northern Europeans/East Asians.

    Oddly enough, the conditions of modern civilization may once again be lowering the ceiling, since high-IQ no longer appears to be much of a fitness advantage (in fact appears to be a distinct disadvantage). I wish I could find data on fertility as a function of IQ within each race.

  6. JayMan / Jan 22 2012 12:06 AM

    hbd chick :
    coulda sworn i left a comment here the other day, but i guess it didn’t work. let’s try it again! what i said was:

    You did, it was sitting in my “spam” box! :p Sorry about that, blog.com wasn’t nice enough to let me know it was there.

    iq ceilings make a LOT of sense — esp. how expensive the brain is in a hot climate. maybe it’s just not possible to get an average of 90 or above when you live on or near the equator.

    India and the Middle East are of interest to me in this respect. The achievements of Islamic golden age suggests there were some sharp individuals, and that the population was more intelligent that it is now. But, that region continues to church out intelligent individuals and maybe it wasn’t so much IQ but cultural/sociological conditions. Maybe the peace brought about in the wake of the Arab conquest allowed the well-to-do free time to focus on intellectual pursuits (in addition to the flow of new ideas brought in from the many lands the Muslims contacted).

    As well, India seems to have a layered caste system with their equivalent of Ashkenazi Jews, the Brahmins. But then, the like the Jews, the Brahmins live as a minority within a population who can do the dirty jobs for them.

    you said: “Perhaps the IQ differences were pre-existing in the various populations, and I believe they most likely were—to an extent.”
    i was thinking along the same lines, too, and that the selection pressure i was talking about (from the medieval period) just sorta tweaked the germanic iqs a little higher. like you say, it’s interesting that the finnish iq is so high. (or does that high average iq score reflect all the swedes, i.e. germanic peoples, in finland? that thought crossed my mind. dunno.)

    Russia and Poland also appear to have high average IQs (~98, which is not too far off from 100), and the Russians at least seems to have lived in community families like the Finns. Maybe this is climate X family structure. While individuality is discouraged under such a system, the brutal winters (and likely limited food supply) perhaps led to fairly heavy attrition of the poorest individuals (maybe whole under-performing families). Russia for example had a well-off aristocratic class who might have made sure to fill their own bellies first, even though there was a more equal-share proto-communist mindset at play.

    your scenario of south american indians losing iq points is not far out at all. you saw this post by greg cochran, yes?

    Yes I saw that. Try as I might I couldn’t find the reference for the lowered IQ of Tropical Native Americans, other than Jason Malloy’s page. Up and down the Americas, there is definitely a cline in brain size that correlates with latitude—highest in the far north, decreasing towards the equator, then increasing again towards Patagonia. The fact that the people of Tierra Del Fuego evolved large heads again in under 7,000 year indicates that this process can operate fairly quickly. It is too bad we don’t have IQ data to indicate whether their intelligence increased as well.

  7. Jack / Jan 22 2012 1:26 PM

    Wikipedia’s Hajnal line map is erroneous. Finland also traditionally exhibited the “Western European marriage pattern”, at least Western Finland. Peter Frost wrote about a study of preindustrial Finns which found that the average age of first child for mothers was 26: http://evoandproud.blogspot.com/2011/11/how-late-is-too-late.html

    • JayMan / Jan 23 2012 6:28 PM

      Yeah I thought there was something off about Finland. Emmanuel Todd’s stuff indicates that while coastal Finland practiced the stem family arrangement, the interior was organized into community families. Perhaps the Finns adopted the community family before 1800, then switched to stem families with late marriage and primogeniture afterwards?

      Interestingly, the World Values Survey shows Finns espousing values similar to their Scandinavians neighbors rather than their former communist ones. It may be that the family structure described by Liu and Lummaa—which is more in line with Western Europe—might have something to do with it.

  8. Steve Sailer / Jan 22 2012 6:23 PM

    Thanks. One possible line of investigation for your theory is whether Jews can maintain their lead in IQ over gentile whites and Asians or whether they run into diminishing returns. I don’t know what the answer is, but in say National Merit Scholars from California, the ranks used to be heavily Jewish but are not heavily Asian.

    • JayMan / Jan 23 2012 6:16 PM

      My suspicion is that genotypic IQ for all races is likely decreasing thanks to dysgenic breeding (i.e., the modern-day IQ ceiling is lowering). But it’s an interesting question whether or not it would go down for some groups faster than others. I’d imagine that any possible losses in average IQ that Jews sustained by intermarriage with gentile Whites would be balanced by assortative mating in such couplings. Seems to be a good reason to look at fertility rates broken down by race as a function of SES and education.

      Could Asians be now dominating merit scholarships simply because there are more Asians in America today, particularly in CA?

    • Steve / Jan 30 2012 2:05 PM

      …even though actual IQ scores have been rising globally for as long as IQ has been measured.

  9. Steve Sailer / Jan 22 2012 6:30 PM

    I believe Rindermann has reviewed IQ scores from sub-Saharan Africa and suggests an average of 80 as more plausible than 70 on tests that actually worked well.

    • JayMan / Jan 23 2012 6:02 PM

      There doesn’t seem to be a free link to Rindermann’s 2007 paper anymore, unfortunately. But from what I gather of that paper and his and Sailer’s & Thompson’s 2009 paper, it would seem that Rindermann’s data corroborates an average IQ of 70 for sub-Saharan Africa. As well, there’s Lynn’s & Meisenberg’s 2010 study that looked at achievement tests and found a similar number.

      Of course, there could easily be lots of stuff out there that I’m not aware of, and I’d be more than happy if you could point me in the right direction. 🙂

  10. Gorbachev / Jan 23 2012 5:56 AM

    The piece has a few flaws, which will be picked apart mercilessly by detractors; but the overall thesis is solid. It certainly makes an attempt to account for reality and for data.

    The strength of this argument is less in its details, and more in its overt acknowledgment that breeding practices and social patterns that affect breeding on a macro level will provide a powerful selective force, which will have an immediate and profound effect on the genetic makeup of a population.

    At some point, especially when the human genetic map is no longer just a series of nameless genetic descriptions but is a comprehensive catalog of human traits, both social and physical, those critics with major beefs with this kind of analysis will have to shift trajectory.

    I think it’s likely that they’ll start advocating selective breeding and social policy engineering to promote what will be, for want of a better term, eugenics. All social policies that in any way touch on breeding patterns are eugenic: whether consciously selected or not.

    As lefty-marxist types, once they accept that biology plays a powerfully limiting role, they’ll seek equality of social outcome through selective breeding when social modification is shown to fail, and when we understand why this is so.

    Eugenics was fundamentally a progressive concern. It will become so again.

  11. JayMan / Jan 23 2012 6:38 PM

    Gorbachev :
    The strength of this argument is less in its details, and more in its overt acknowledgment that breeding practices and social patterns that affect breeding on a macro level will provide a powerful selective force, which will have an immediate and profound effect on the genetic makeup of a population.

    We have Gregory Cochran, Henry Harpending, hbd* chick and a few others to thank for that. It seems to make much more sense that the modern IQ levels and even differences in personality and social and political factors have fairly recent origins, at least to some degree.

    At some point, especially when the human genetic map is no longer just a series of nameless genetic descriptions but is a comprehensive catalog of human traits, both social and physical, those critics with major beefs with this kind of analysis will have to shift trajectory.

    At some point. Many rather compelling discoveries have been made and this stuff is still well outside the mainstream. Acceptance of HBD by the mainstream will require a massive paradigm shift in today’s society. It may be a long a painful process to get there, tho.

  12. hbd chick / Jan 25 2012 3:16 AM

    Jack :
    Wikipedia’s Hajnal line map is erroneous. Finland also traditionally exhibited the “Western European marriage pattern”, at least Western Finland. Peter Frost wrote about a study of preindustrial Finns which found that the average age of first child for mothers was 26: http://evoandproud.blogspot.com/2011/11/how-late-is-too-late.html

    i think — but i’m not sure because i haven’t seen the book — that finland is outside the hajnal line on wikipedia ’cause the info for that came from Family Life in Early Modern Times, 1500-1789, whereas the article peter frost quotes dealt with the eighteenth and nineteenth centuries. slightly different time periods — a bit of an overlap — but maybe this is where the discrepancy is coming from (i.e. maybe the finns changed their mating patterns).

    or maybe the hajnal line on wikipedia is just wrong (say it ain’t so!). to be investigated further! (^_^)

  13. Steve / Jan 30 2012 2:00 PM

    Average IQ’s have been rising by about 3 point per decade for the past 100 years. why should we suddenly have reached the ceiling?

    • JayMan / Jan 30 2012 4:11 PM

      Average height has been rising in about the same manner during a similar period. Just as we likely don’t have genotypically increased height than we did 100 years ago, we probably don’t have genotypically increased IQ. It’s also unclear if we even have phenotypically increased intelligence, as there is evidence that the Flynn Effect in IQ is not on g.

      Also, the current US black IQ is higher than the white IQ was during WW2. Current US blacks would actually outscore world war 2 whites on the IQ tests of that time. Makes you wonder, doesn’t it?

      While it has been suggested that improved nutrition is the cause of the Flynn effect as it likely is for height, if raw IQ scores are taken at face value, it leads to your stated conclusion, which is highly improbable. Rather, it seems that people are just better at taking tests today than they were in the past. In other words, due to better schooling and more familiarity with paper and pencil tests, IQ tests are slowly losing their g-loading.

      I want it to make it clear that the IQ ceilings that I propose aren’t immutable or permanent; they are dependent on the social/environmental context. In pre-modern times, climate was a much bigger factor in survival than it is today, as such, the way a society was structured much more centered on the climate in a given location. Modern industrial society has both relieved some of that dependence and removed some of the selective pressure favoring increased IQ (and indeed, may have introduced selective pressure favoring decreased IQ).

  14. Steve / Jan 30 2012 2:02 PM

    Also, the current US black IQ is higher than the white IQ was during WW2. Current US blacks would actually outscore world war 2 whites on the IQ tests of that time. Makes you wonder, doesn’t it?

  15. darkanddeep / Jul 27 2012 1:26 PM

    Hi Jayman, your blog is interesting and interesting.

    Are you completely sure that the Inuit have large skulls/brains, though? To say nothing of the largest.

    I’ve searched to verify this a few times, but each time I get a negative result. I suspect that this is a blogosphere “proof by repeated assertion” factoid, without data to back it.

  16. Anonymoose / Dec 24 2012 12:36 PM

    @ Jayman: A question I think the HBD community should consider is that while the average IQ of many groups may be decreasing, what may the effects of modern society have on the variance of the distribution? For example, perhaps smart people are finding eachother more and more due to increased cognitive sorting and jobs are more and more stratified for IQ. Basically, are we heading towards a caste society?

  17. Chris / Feb 17 2013 1:33 AM

    If the African ceiling is 70, why do black Americans average 85(I think it maybe as high as 87 now by some estimates). I don’t think the admixture of 15% European blood could account for that much of a boost.

    I’m not saying everyone has the same genotypic IQ worldwide, but that the African average may have higher genetic potential but since they do not live at a Western standard of living, they might not see their full potential. Do black Africans born and raised in England and France have IQs of 70? We can’t forget that a significant minority of IQ is determined by environment and poverty does depress IQ scores. The poorer white countries(e.g. Balkans, Mediterraneans)have lower IQs.

    The genotypic African-European IQ gap may only be about half of what we think it is judging by African-American scores.

    • JayMan / Feb 17 2013 10:31 AM

      The sub-Saharan genetic potential average IQ is probably around 80, but the adverse conditions of Africa causes most of the population to fail to reach their full potential. The 5 point advantage of African-Americans (85 vs 80) is probably due to White admixture.

  18. Garrett / Jan 23 2014 9:20 PM

    One caveat with this theory: climate isn’t necessarily determined by latitude alone. Factors such as altitude (elevated regions are cooler) and proximity to large bodies of water (wind currents) also strongly influence climate. For example, the mountainous regions of Peru which were the seat of the Inca Empire are much colder than you’d expect from its latitude.

    While I’ve mentioned Peru, I’ve recently discovered that they’re actually doing much better than many of their neighbors, both economically and in international competitions.

    For example, are you aware that Peru (and to a lesser extent Mexico) have both performed respectably at the International Math Olympiad over the last 5-7 years?

    http://www.imo-official.org/results.aspx

    Compare their performance to that of wealthy European countries such as Finland, Denmark, Norway, Sweden, France, Iceland, Latvia, Luxembourg, Belgium, Ireland, Estonia, etc. In fact, many of the Scandinavian countries have consistently performed poorly at the IMO over the last couple of decades.

    What’s particularly interesting about Peru is that almost ALL of the team members from the last decade are visibly brown and Mestizo, which runs against the stereotype of Latin America’s elite having lighter and more European features.

    http://www.imo-official.org/country_individual_r.aspx?code=PER

    Many of the individual profiles there include pictures so you can see their complexion.

    Mestizo Peruvians have also performed well at international chess competitions and the Chemistry Olympiad. It looks like Peru has produced a relatively impressive Mestizo smart fraction in recent years, which makes you wonder if those other countries might have untapped potential as well…

  19. Garrett / Jan 23 2014 9:31 PM

    You might also want to google Raúl Chávez Sarmiento. a child prodigy from Peru who is the second youngest medalist in IMO history (surpassed only by Terence Tao).

    Here he is with some of his teammates from the 2011 IMO:

    (He’s the first and shortest one on the left)

    According to an interview, he has two siblings who work as a physicist and a mathematician respectively, which means he wasn’t a fluke either.

    Also of note are the siblings Jorge and Deysi Cori, both of whom achieved Chess Grandmaster status while teenagers:

    As a point of comparison, I’ll mention that there are only three Chess Grandmasters of African descent *in the entire world* and none of them won the title as a teenager.

  20. angel quesada / Jan 16 2016 9:07 AM

    I was fascinated by your article but with your permission will add some historical facts . There are some sense in the latitude theory but discard it by the inuits example need other angle . The inuits adaptation is physical with short limbs better adapted for freezing temperature . We can postulate that at that temperature that is all needed . No planning for agriculture just hunter gathered at low temperature . Remember that Vikings with very high IQ from Iceland start conquering Greenland and even get to Newfoundland . Climate deteriorate and the colonies disappeared . On template Europe the Neanthertal had no match , their short limbs and the and corpular body was ideal for ambush of big mammals in the forest . After Ice Age cause disappearance of forest in Europe making hunting by ambush difficult (since the body feature of Neanthertal make it difficult hunting at distance by throwing the spear or ache) plus the need of near double quantity of daily calories (in comparison to homo sapiens) on scarce condition ; cause it extintion . By the way it is generally accepted that at that time humans had no other advantage meaning social , mental or arms production . There are other evolutionary traits not only IQ that define adaptation advantage to evolution and explain difference in IQ thru time . During 1200-1500 hunter gatherer mongols destroy all the known CIVILIZED WORLD from east central and middle east ASIA to Russia and Eastern Europe killing millions of posible high IQ individuals . Reducing population of China from 120M to 60M in Persia 2.5M to 250000 in Ukraine and eastern Europe half population in Central Asia if displacement is included near all population . Other examples of IQ displacement is movement of Vikings to European south nations and migration of Germans-Visigods to France and Spain , Arabs to North Africa , Spain and East as far as Persia . And others as Vandals , Huns , Ottomans , Greeks , etc etc . About American Natives is true that they come from Asia but their population origin is not todays Asians . It was replaced , as can be seen by todays Asians are blood type is A but Native Americans is B . The final analysis to conclude any relation will be comparing IQ and DNA . But even that will not help much as my DNA show me to be 12% IRISH 8% BRITAIN 12% NORTH AFRICA 8% ARAB 30% ITALIAN-GREEK 20% SPANISH and 10% FRENCH . My IQ is 134 .

    • JayMan / Jan 19 2016 10:48 AM

      There are some sense in the latitude theory but discard it by the inuits example need other angle . The inuits adaptation is physical with short limbs better adapted for freezing temperature . We can postulate that at that temperature that is all needed . No planning for agriculture just hunter gathered at low temperature

      But they also have larger brains. They also have much higher average IQs than tropical hunter-gatherers.

      By the way it is generally accepted that at that time humans had no other advantage meaning social , mental or arms production

      “Generally accepted?” By whom? And does that matter?

      During 1200-1500 hunter gatherer mongols destroy all the known CIVILIZED WORLD from east central and middle east ASIA to Russia and Eastern Europe killing millions of posible high IQ individuals

      The Mongols weren’t hunter-gatherers. They were herders. Big difference.

      Other examples of IQ displacement is movement of Vikings to European south nations and migration of Germans-Visigods to France and Spain

      In neither case was the native population replaced.

  21. George Woelfel / Apr 18 2016 10:09 AM

    With the outbreak of the Zika virus, could there be a virus spread by mosquitoes that is less severe than Zika that could affect intelligence? Are mosquitoes in these tropical environments inoculating indigenous people with a dumb down virus?

    • JayMan / Apr 18 2016 10:11 AM

      I certainly wouldn’t rule it out. Africans appear to be less intelligent than Africans outside of Africa would indicate, for example.

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