If two populations have moderately different means for some quantitative trait,  for example differing by one standard deviation, the fraction that exceeds a high threshold is very much larger in the population with the higher mean.

I have mentioned this once or twice before, but it’s worth explaining in some detail.  It has some important consequences, and I have the feeling that there are actually a fair fraction of Harvard graduates who aren’t familiar with it.  

This is a natural consequence of the shape of the distribution function. It certainly happens with a Gaussian distribution (and many traits are roughly Gaussian), but it will be true for any distribution function that declines more and more rapidly as you get farther from the mean.

In practice, this means that if population A is significantly taller than population B,  people from population A will account for a surprisingly large fraction of people taller than 7 feet.   The effect is particularly strong for the tallest people, the farthest outliers – they may all be from group A, even when there are far fewer people in A.

There are quite a few cases in which we care a lot about outliers.  In athletic competitions, you’re not really interested in the strong & the fast – you’re interested in the fastest, the strongest.  In  research, it helps to be able to solve puzzles that others can’t: being the smartest, rather than just smart, improves your odds.

Because this effect is so strong at the highest levels, you can run it backwards to come up with useful inferences.  A priori, anything that screwed up the brain enough to misdirect sexual orientation might well decrease average intelligence as well: but the existence and accomplishments of Alan Turing and G. H. Hardy strongly suggest that this is not the case. Running it forwards, you would expect to see very few, maybe zero, top-flight mathematicians (the top 1000) from populations that have low average IQs – and that is the case. You would also expect to see a vast over-representation in mathematics from a population with a significantly higher-than-average IQ, such as the Ashkenazi Jews – and again that is so.

In another application – if the average genetic IQ potential had decreased by a standard deviation since Victorian times, the number of individuals with the ability to develop new, difficult, and interesting results in higher mathematics would have crashed, bring such developments to a screeching halt.   Of course that has not happened.

At the limit, this means that families that score high on some quantitative trait, who are from a group with high mean values of that trait, live in a suitable environment,  and whose high scores happen to be almost entirely due to genetic factors rather than good developmental luck, can be competitive, at the highest levels, with entire continental races.  For example, there’s the Bekele family, from Bekoji, Ethiopia.  Kenenisa Bekele holds the world record at 5,000 and 10,000 meters, while his little brother is the 3,000 meter world indoor champion.  That one family is competitive (in running) with China, population 1.35 billion. 

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137 Responses to Outliers

  1. dearieme says:

    ” That one family is competitive (in running) with China, population 1.35 billion.” So that’s why they want Tibet.

  2. JayMan says:

    Nice dig at Malcolm Gladwell, and quite a few others, apparently. 🙂

  3. Arntor says:

    Christophe Lemaitre should focus on finding himself a tall and fast wife in stead of pursuing that stupid bachelor in industrial electrical engineering and computer science;)

  4. Richard Sharpe says:

    I rmain blissfully ignorant of any such thing.

  5. melendwyr says:

    “In another application – if the average genetic IQ potential had decreased by a standard deviation since Victorian times, the number of individuals with the ability to develop new, difficult, and interesting results in higher mathematics would have crashed, bring such developments to a screeching halt. Of course that has not happened.”

    If the relative proportion of the population with a certain level of intellectual potential is halved, but the population doubles, the absolute number of ‘smart’ people remains the same.

    And, of course, it’s worth paying attention to which people are contributing to the population increase and which people are making the mathematical discoveries. It’s not difficult to imagine a scenario in which the number of people concerned with such abstractions remains constant or even increases, while the number of people who couldn’t manage such things even with motivation increases much faster, leading to a drop in ‘average’ IQ even as the abilities of the mathy group remain constant.

    If the number of Isaac Newtons doubles, while the number of Homer Simpsons increases a hundred-fold, you still have twice as many geniuses as you had before.

    • gcochran9 says:

      A one std change would drop the fraction above, say, IQ 160 by way more than half. More like a factor of 20. If there had been a 1 std drop, higher mathematics would have collapsed, like I said.

      • dave chamberlin says:

        I am not debating your statistical reasoning, it is absolutely solid. However your statistical reasoning assumes the same degree of randomness through time in the the pairing of parents and that clearly is not happening. There have been two radical changes in society that have increased the chances of high IQ people to choose each other as mates. First after World War Two upward mobility of high IQ students into the best colleges was greatly increased by the introduction of college entrance exams that are a kind of IQ test. Secondly the barriers blocking women from high IQ college majors and the follow up job market were removed. Allow me to make an interesting comparison to make my point. My mother at age 22 in 1945 was in grad school at Ohio State just like your daughter Ginny is. Her major was art not physics, my mother was in college by age 16 and was continuously pressured to take a woman’s major and had to pretend not to be extremely smart. My mother acted pretty, which she was, and married a smart jock. But not smart enough apparently, as they later got divorced because they really weren’t that compatible. If and when Ginny chooses someone as a mate to have children with, it will far more likely be someone of similar IQ than was the case for my mother back in 1945. So what I am suggesting is there could be a decline in average IQ and there remain a similar or even higher number of super geniuses if there is major change in the patterns of assortive matings as I have reason to believe there has been.

      • James says:

        I’d be grateful if someone would explain how one can talk about a decline in IQ when for most of the 20th century there was a massive improvement in IQ test scores from one generation to another. If these differences in IQ results between generations are dismissed as not indicative of real intelligence gains, and certainly not due to genetic differences between generations, then how can one use similiar IQ differences between populations as evidence of genetic-based disparities in real intelligence between races?

      • Dalliard says:

        James, IQ differences between generations are qualitatively different from differences between contemporary groups. In the US, IQ differences between same-age people from different races are qualitatively indistinguishable from individual differences within races; the same factors appear to cause within- and between-groups differences. This is not the case when you compare different generations, making it difficult to decide if intelligence is actually increasing. I discussed this issue briefly and listed some references towards the end of this post.

      • Asher says:


        In terms of numbers, what melandwyr is saying i that the distribution, itself, has significantly changed during the same period that the mean has changed. I agree that one stdv decrease would have caused a collapse in higher mathematics but a change in distributions, combined with an absolute increase in population, could counter a decrease in the mean.

      • melendwyr says:

        “If there had been a 1 std drop, higher mathematics would have collapsed, like I said.”
        Perhaps it has collapsed. I’m not certain that we know what a constant level of mathematical talent and accomplishment would look like, or what a reduction would look like. You already accept that major schools of intellectual inquiry are spinning their wheels, expending a great deal of effort without accomplishing much. Why presume that mathematics isn’t in that state now?

        How do we measure actual progress in math? And if the rate of progress has changed, how do we determine what the underlying cause is? Presumably if Poincaire or Newton or Euclid were born again today, they wouldn’t have a meteoric rush of discoveries because all the low-hanging fruit has been taken. How do we distinguish between the low-hanging fruit being taken from a reduction in our ability to gather fruit?

        What if the greater mass of the populace hasn’t changed much, but the extreme right side of the distribution has shrunk? You can truncate the tails without having much of an effect on the mean, and only a small effect on the standard distribution.

      • melendwyr says:

        “It hasn’t.”
        Relative to what?
        How do we distinguish between the slowing of radical shifts because all of the easy work has been done, and the slowing of radical shifts because the talent has gone out of the field?
        I have no doubt that the first factor is a major reason why we haven’t seen revolutionary changes to mathematics and physics, among others. What I want to know is how we can determine whether, and to what degree, we can also eliminate the second as a possible influence. There are many potential factors involved – the structure and motivation of our institutes of higher learning, the amount of funding given, the ways in which talented people are motivated to do into different fields, and so on.
        I am particularly interested in whether we have any way of determining whether
        intellectual factors not measured by IQ but vital to actual intellectual functioning and achievement might have changed. We know beyond all doubt that massive frontal lobe damage does not impair IQ, yet it obliterates the ability to learn and act in ways more complex than immediate impulse. We also know that the related functions are more delicate and easily disrupted than others.

  6. Sandgroper says:

    It gets even more interesting that the Bekele brothers and the Dibaba sisters and their cousin Derartu Tulu all come from the same town in the Ethiopian highlands.

    Someone needs to do some genomics and/or genealogy, to find out how closely related the Bekeles and the Dibabas are.

    • Sandgroper says:

      Relevantly, Tirunesh Dibaba is the only woman in history to win gold medals for both the 5,000m and 10,000m in the 2008 Olympics in Beijing. She also won the gold in the 10,000m in 2012 in London. Her older sister Ejegayehu won the silver medal in the 10,000m in the 2004 Athens Olympics – she had to beat cousin Derartu Tulu to do it. Younger sister Genzebe is now one of only three athletes in history to break three world records in three different events in under two weeks (the others being Jesse Owens and Usain Bolt), in the indoor 1,500m, 3,000m and two miles – she’ll be worth watching in the 2016 Olympics.

      The really scary part is that Tirunesh is married to a two time Olympic silver medallist in the 10,000m.

      • gcochran9 says:

        Reminds of a bit in Parkinson’s Law, on the principles of selection. He describes the ideal candidate for the Royal Navy:

        “Yes, Admiral Parker is my uncle. My father is Captain Foley, my grandfather Commodore Foley. My mother’s father was Admiral Hardy. Commodore Hardy is my uncle. My eldest brother is a Lieutenant in the Royal Marines, my next brother is a cadet at Dartmouth, and my younger brother wears a sailor suit.” “Ah!” the senior Admiral would say. “And what made you think of joining the Navy?”

      • dave chamberlin says:

        Besides good genes there is the other factor of having chemists that are more advanced than those that administer the doping tests. There was the wonderful story of the Chinese women’s swimming team that hired the recently unemployed East German coach back in 1992. Miraculously the 10th ranked in the world women’s Chinese swimming team not only placed first, second, third, and fourth in some events but they all broke the world’s record. It was so obvious what was going on that the whole team got the boot. Now we have more difficult to detect means of doping than just steroids. HGH, an extra quart of your own blood put back in your veins right before the race, the list goes on and on. To quote Mark Grace, a professional baseball player back in the days when the union blocked any testing what so ever “if you aren’t cheating, you are just not trying.”

      • Sandgroper says:

        You’re missing the point.

      • Sandgroper says:

        Dave, to be specific, these people are not like the Chemical Sisters trained by Ma Junren, who suddenly out of the blue began running incredible times, when Chinese women had never excelled at these distances, or the Chinese swimmers who suddenly began winning everything when there was no prior history of excellence. They are from families who are all fast in a town full of fast people, in a region full of fast people, with a long history, and they show up as elite level athletes who are winning world championships while they are still in the juniors. Their physiognomy is perfect for the distances they run – if you were to design a 3,000 m runner, you would design Genzebe Dibaba. Biomechanically she’s perfect for the job, and she’s inherited the high altitude magic in spades. They are not state-funded, they have no money, no equipment, no facilities, they share one local coach, they train on the local village green or whatever it is, and they still win all the championships as juniors. If they are doping, they have been doing it since they were kids, which is not credible. When they were kids they were running up and down hills collecting firewood. They don’t need blood doping, they are born that way.

        It is easy to be cynical and cast doubt, when there is no evidence, and not even a hint of suspicion. If they are doping, which I really doubt, then everyone is doing it, and they are still winning. It is not doping that is giving them an advantage over very large nations with lots of resources, and not just good genes – damn near perfect genes in the few who make it. Check out how many Bekeles and Dibabas have been runners – lots. They have been breeding dynasties of runners. If there is any evidence of anything here, it is selective breeding.

        And they eat teff. I might have to start trying to grow some.

        Check her out against Wang Junxia – no comparison: http://www.vo2.fr/typo3temp/pics/1d0a3679ae.jpg

      • dave chamberlin says:

        I didn’t mean to question your excellent post sandgroper, just throw in an unrelated true detail of international competition that I thought readers would like to hear. Off topic from what you were saying? yea. I like your posts, I didn’t mean to sound like I was questioning anything you said.

    • Paul Conroy says:

      You see something similar in the World’s Strongest Man competition, as places like Iceland with 300K people regularly finish in the top 5, way ahead of China’s Billion+ people.


      • Sideways says:

        Yes, but WSM is a niche sport that doesn’t drug test. Yeah, some populations have much better physiques for it, but the big thing there is caring enough to train and juice a ton

      • Paul Conroy says:


        I don’t agree with your characterization of WSM… yes they don’t drug test, but that just means that everyone is on a more level playing field than current so called “amateur” sports! IMO most of the winter olympic events are niche/obscure, whereas strongman events are thousands of years old, like the Greek tradition or the Irish Tailteann Games:
        or the Highland Games.

        The fact is that Iceland’s current contestant Hafþór Júlíus “Thor” Björnsson is a 6′ 9″, red-headed giant, who weighs about 420 Lbs, and there is nothing like that in all of China. The US contest Brian Shaw is a 6′ 8″ and 415 Lbs by comparison, and both men standing together look like cousins.

    • Steve Sailer says:

      East Africans have been winning Olympic distance running races since Bikele in 1960, but there was a Great Leap Forward in times around 1995 that probably had to do with the drug EPO.

  7. We see this locally and no one thinks it remarkable. Two brothers and a cousin lead high school teams to championships over a decade, and a generation later their sons or daughters figure prominently at the same school and everyone knows why.

    We also know it in music or in academic work, where sibling pianists, valedictorians, or science-fair winners show up a few years apart. Even those who lean heavily on the idea that the athletic, musical, or academic environment has played a large part also know that a lot of the ability was “just there” from the start. Often this is because we ourselves went to school with someone else in the family and saw how quickly they picked things up. We see that an uncle who didn’t work as hard at it was still pretty darn good, and we know that genes played a big role.

    Only when we start to generalise this across populations do folks balk.

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  9. Harold says:

    “For example differing by one standard deviation.” This amused me, I imagine if Cochran had spoken it he would have waved his hand in a circular manner.

    “The fraction that exceeds a high threshold is very much larger in the population with the higher mean.” Depends on the variance.

  10. D says:

    Taleb on this.

    • misdreavus says:

      Other than mountains of psychometric evidence, we have no reason whatsoever to believe that the “mean” in scientific aptitude among, say, Norwegians, is any higher than it is among the gulf Arabs.

      I’ve never bothered reading any of Taleb’s books. Judging from some of his op-eds that I’ve read, I don’t think I’m missing out on very much. Am I right or wrong?

      • T. Greer says:


        But he does load his books with a lot of pretence and minutiae. He could easily take The Black Swan and cut it down to 40 pages without losing any of the real content.

      • gcochran9 says:

        There’s better evidence than psychometric results.

      • misdreavus says:

        What? Like historical behavior?

      • Patrick Boyle says:

        Taleb is a professional guru rather like Malcolm Gladwell. He used to be a trader and he had his one great mathematical insight. He realized that the assumptions of normality in financial analysis were often not fulfilled. Others before him had realized that many distributions in finance had ‘fat tails’ but most had ignored that fact so as to continue to take advantage of standard statistics based on normality.

        If you base your decision making on imperfect math there are consequences. Most traders periodically ‘blew up’. They would have long runs of success and then lose everything on a single bad day. Taleb developed a method to avoid these periodic blow ups. First of all he never invested all his money. He kept a large reserve in the bank. Secondly he developed a strategy for losing a little everyday by betting against the market. Then when the big correction happened he made money while everyone else went bust.

        Gladwell interviewed him and wrote a famous piece about the effect all this had on him. Apparently it was driving him nuts. When the markets were hot and everyone else was doing well, Taleb lost money continually. When the day of reckoning came and everyone else went bust, Taleb had a good day. But only one. Taleb had strategy that made him suffer continually and it drove him nuts. Or at least that’s what Gladwell wrote.

        Taleb quit trading and started writing guru books. He’s bright and well read – unlike Gladwell – but his statistical insight has little practical value.

      • Peter Lund says:

        Oh yes, old man Selberg.

  11. j3morecharacters says:

    The concept of outliers is crystal clear, but from the fact that high math flourishes today in a country does not follow that the average IQ of that country did not fall. Not in theory and not in fact. The theoretical framework was developed by La Griffe (2004) and V.Weiss (2009), and for the facts please visit the Math Dept. of your or any university. You’ll find a different population from a generation ago (more East and South Asian faces). When the generation now in day-care (average IQ 87) starts working on their math doctorates, you will find few pallid faces among them. Yet Math will prosper as maybe never before.

    • Harold says:

      The group photos of mathematics conferences and the like that I come across tend to look like the one here:

      Out of interest I took a look at the last names of the top 50 contributors to mathoverflow who used their real names for their user accounts (which was most of them), they were:

      O’Rourke, Beenakker, Degtyarev, Holt, Zaimi, Myerson, Hamkins, Yuan, Sawin, Belk, Bauer, Rivin, Zare, Weaver, McKay, Speyer, Elkies, Bryant, Agol, Caicedo, Blass, Jeřábek, Kuperberg, Lawson, Eremenko, Kjos-Hanssen, Humphreys, Quas, Stanley, Isaacs, McKay, Johnson, Petrunin, Strickland, May, Knutson, Pak, Clark, Henriques, Polizzi, Tao, Trimble, Robinson, Taghavi, Crooks, Putman, Dorais, Majer, Anan’in, Shahryari

      Those are the top 50 contributors from this quarter, I would rather have looked at all time contributions but only noticed I wasn’t too late to bother starting again. A quick look suggest it wouldn’t make much difference to the ethnic mix.

      • Anthony says:

        When I was at Berkeley, one day I stayed late after a lecture to organize some papers and notes (I’d rushed in a little late to class), and notices the lecture hall filling with Indians and Russian Jews. I stayed long enough to realize that the next lecture was a graduate-level math class, which by that point was *not* a surprise.

    • j3morecharacters says:

      You people dont read what is written but what you wish to read. A photograph of elderly mathematicians does not answer my thesis.

  12. Christian says:

    Anybody know what sort of contribution to top-flight maths is currently being made by NE Asians, and what has it been? How many are in this top 1000? When you think of the greatest ever mathematicians does anyone not European come to mind?

    I’m wondering if there is any scope for separating an element of creativity at this level from IQ intelligence, a creativity particularly evident amongst the Ashkenazis.

    • RS says:

      Creativity net of IQ appears slightly higher in Europids than Ashkenazim. That, along with a very large population advantage of course, is why Europids match or exceed them in absolute amount of (genius-level) achievement in almost all fields. In the arts and Continental philosophy, Jews are hardly overrepresented at all vs Europids, per capita. In general sciences this is much less true, and in physics, obviously, Jews are overrepresented vastly. I don’t know anything about math but I suppose the picture is like that of physics, or even more extreme.

      I’m depending here on the postulate/observation that creativity is – mildly – less determinative in physics than in biology, and less so in bio than in music: Bohr might be as creative as Mozart, or moreso, but creativity doesn’t do him quite as much good in his work. IQ does more. In biology, which lies between physics and music, you’ll sometimes see a genius insight by someone like Lynn Margulis, who appears to be ultra-creative but who I think might struggle to just get a high-quality PhD in physics. I don’t think that can happen in physics: you might be a mind-blowing person who brainstorms all kinds of cool stuff that just does not occur to people, but without a 160+ head it seems unlikely you’ll finish up anything historic.

      This tallies, because when you look at the writings of genius artists, they are quite smart but it doesn’t seem like their IQ is 160. Take Kokoschka, for me the truly staggering painter of the last century (though very uneven): interviews with him are interesting but far from Wow, just wow! Tarkovskij, same. There are great interviews with him on youtube, but you don’t say “so, this guy just understands everything and I just don’t”. Yet watch ZERKALO and it’s “this guy just understands everything, and I understand nothing.”

      Again I don’t know math, but there are fairly few E-Asians when you look at the science nobels. There certainly are some, and in the future there will be rather more for pretty obvious reasons.

      What I know is bio and there the Nobels seem rather objective. Some of the awards are probably somewhat debatable ; many are not up for debate. Warren and Marshall nab Helicobacter, they get the prize, obviously. Who can argue about it. Mullis does PCR, he gets the prize. He knew he would, the day or week he got it running reproducibly. Somehow Oswald Avery didn’t get it and few know his name. Charles Darwin he ain’t, but his import is barely below Crick or Pauling. Incidentally Darwin does not sound crushingly intelligent, yet he discovers sexual selection as well as natural selection proper. Would he have been able to make a great mark in world wars era physics, supposing that to have been his heart’s desire?

      • Patrick Boyle says:

        The single most important fact in psychology is that intelligence is general. Hence the ‘g’. Many white people are uncomfortable with that fact especially now that it is accepted that the IQs of East Asians are a little higher than those of Western Europeans. One popular escape from that crushing reality is in the comforting concept of ‘creativity’.

        There is no accepted test for creativity. There isn’t even much agreement as to what it means. So you can console yourself to the average IQ of 105 that South Koreans have with the ‘knowledge’ that Koreans are less creative. Creativity is now the ‘elan vital’ or ‘spiritual essence’ that lesser races were said to have missing in earlier days. It is numinous and ineffable.

        Invoking Mozart doesn’t help. Musical ability is not part of general intelligence. It is not supported by the same neural structures. IQ correlates about .40 with total brain size (mostly differences in the size of the neocortex) but musical ability seems to be centered on only the superior anterior gyrus. Talk sometime with a member of the violin section of any major orchestra. They are likely to be dumber than a box of rocks. Yet their musicianship is superb. Most people who don’t know musicians are surprised to find out how intellectually limited eminent musicians often are. All this means is that brainpower is general but musical ability is an exception.

        The Asian brain seems to be organized a little differently that the Caucasian brain – just as the male brain is a little different than the female brain. East Asians are several points smarter than Europeans on the quantitative subtests and a few points less smart on the verbal subtests. Since their non-verbal advantage is greater than their verbal disadvantage on average they are a little smarter. There may also be a difference in variance such that Europeans have a higher variance. This might mean that there are more European geniuses – and idiots.

        Lynn and Vanhatten have shown that national IQ correlates at about .40 with GDP. Many in the West assume that national achievement is determined by the extremes of the IQ distribution. – a sort of ‘Great Man’ theory of history. This is the theory that a few geniuses are what matters in history. It could be true but it has certainly never been demonstrated.

        The genius theory is flattering to Westerners because it may be that there are more extremes among Europeans than among East Asians. However at this point that is just a speculation. But even if it’s true that the Western European genome produces more ‘outliers’ than the East it is not established that the extremes are so important. in wealth creation.

        Gregory – a very smart guy – is invested in the genius theory of wealth creation but so far this is just a speculation. We know with pretty good certainty national IQ is important because there have been millions of test subjects, and thousands of studies. Does GNP correlate with number of Nobel winners? Or Mensa members?

        In fact the threshold IQ of Mensa members is only about 128 and the average IQ of Nobel winners is only about 145. Those figures are not that impressive. I can’t think of any easily obtainable statistics on the really smart contributors that would qualify as ‘geniuses’.

        Or to put it is another context. Was the simple fact of Barnes Wallace – the famous British boffin – as important to the war effort and the league of Rolls Royce skilled machinists?

        • gcochran9 says:

          If there were three different kinds of intelligence – and in fact there are statistically independent components of intelligence other than ‘g’ – I think it wouldn’t make much difference. Those three numbers would still be useful. No harder than remembering 35D-24-36.

          If I was invested in the genius theory of wealth creation, you’d think I’d know about it.

    • jhobelmam@neweralife.com says:

      The Japanese have made a large contribution to mathematics in the last 100 years. Kodaira, Iwasawa, Oka, Takagi, Hironaka, Mori, Shimura are some of the names that come immediately to mind.

  13. @Greg

    As you presumably know, I have an extremely high regard for your work (e.g. having provided a back page blurb for 10,000 Year Explosion and invited you to write for Medical Hypotheses on the germ theory of male homosexuality).

    And I am – on the whole! – grateful for your opposition to the finding of an approximately 1SD (15plus IQ points by modern measurements) decline in general intelligence in England (and similar places) as measured by simple reaction times since about 150-200 years ago – grateful because it has stimulated me to organize my thoughts on the subject.

    But I continue to think you are wrong! and that the evidence you bring against this decline is inadequate – so I continue to hope to persuade you otherwise.

    I have three considerations to offer.

    1. The decline in question is (roughly) from IQ 115 to IQ 100 over the space of 150 years – about one IQ point per decade (whatever that means!). But I suggest that this would not be expected to have analogous functional consequences to a decline from 100 to 115, since IQ is not an interval scale.

    (In a nutshell, I think Victorian English IQ was *about* the same or a little more than recent Ashkenazi IQ – but has declined.)

    This 150 year decline measure in modern IQ units corresponds to a slowing of simple reaction times from approximately 180 to 250ms for men – about 70 milliseconds.

    And the minimum RT in the Victorian studies was about 150 ms – which is probably near the physiological minimum RT (and maximum real underlying IQ) constrained by the rate of nerve transmission, length of nerves, speed of synapse etc.

    So average Victorian RT was about 30 ms above minimum RT, while modern RS is about 100 ms above minimum.

    By contrast – modern reaction times (in Silverman’s study) for men average approximately 250ms with a standard deviation of 50ms – however there are good recent studies with an average RT of 300ms for men.

    I would argue (on theoretical grounds) that as RT declines there ‘must’ come a point when it comes-up-against the neural constraints of intelligence, such as short term/ ‘working’ memory (the metal ‘workspace’, activation of which lasts a few seconds, seemingly) – and therefore there would be a non-linear effect of reducing intelligence – intelligence would cross a line and fall off a cliff.

    My assumption is that a reduction in (modern normed) IQ from average 115 to 100 would *not* have such a catastrophic effect on high level intellectual (abstract, systemizing) performance as a reduction from average 100 to 85. (At a modern average IQ of 85, top level intellectual activity is *almost* entirely eliminated).

    When we are dealing with the intellectual elites, the same may be more apparent – the initial reduction in RT may retain the possibility of complex inner reasoning; while after a certain threshold the number of possible operations in the mental workspace would drop below the minimum needed for high scale intellectual operations.

    2. It may be that your example of maths does not refute the observation of reduced intelligence. It may be that modern mathematic breakthroughs are of a different character than breakthroughs of the past – and do not require such high intelligence.

    I think this may be correct in the sense that I get the impression that modern maths seems to be substantially a cumulative, applied science – somewhat akin to engineering in the sense of bringing to bear already existing techniques to solve difficult problems.

    So a top level modern mathematician has (I understand) spent many years of intensive effort learning a toolbox of often-recently-devised methods, and becoming adept at applying them, and learning by experience (and inspiration) where and how to apply them.

    This seems more like the Kuhnian idea of Normal Science than the Revolutionary Science of the past – more like an incremental and accumulative social process, than the individualistic, radical re-writings and fresh starts of previous generations. And, relevantly, a method which does not require such great intelligence.

    I also not that many other sciences, from biology to physics, have observed the near-disappearance of individual creative genius over the past 150 years – and especially obviously with people born in the past 50 or so years – which would be consistent with reducing intelligence.

    3. Michael Woodley and I have discovered further independent – but convergent – evidence consistent with about 1 SD (15 IQ point) decline in intelligence from Victorian times, again using simple reaction time data – but, as I say, using a completely different sample and methods. The paper is currently under submission.

    I mention it because the unchallenged consensus post-Galton has been that simple reaction times has some causal – although not direct – relationship to intelligence; and if we have indeed established that RT has substantially slowed over recent generations, then either this would need to be acknowledged as implying a similarly substantial decline in intelligence – or else the post-Galton consensus of IQ depending on RT would need to be overturned.

    • misdreavus says:

      I just can’t wait to see this post being torn to shreds… LOL

      • dave chamberlin says:

        Is it just me or are we getting more serious sounding, intelligent sounding, incredibly long winded guys like BruceCharlton who are starting with absolutely ridiculous assumptions and everybody is too polite to confront them. The guy builds his whole argument that IQ’s have declined around this pearl of wisdom. “We assume that reaction time is a valid measure of general intelligence.” Bruce my boy, nobody but nobody but you assumes any such thing. Do geniuses grab flies out of the air? I’m at a loss for words, and hopefully you are too.

      • MC says:

        “‘We assume that reaction time is a valid measure of general intelligence.’ Bruce my boy, nobody but nobody but you assumes any such thing. Do geniuses grab flies out of the air?”

        Does Arthur Jensen count as “nobody but nobody”?

        “Nevertheless, in recent years, the correlation between RT and IQ has become an empirically well-established fact, based on thousands of subjects in scores of studies conducted in many laboratories around the world.”


        But who needs studies when we can rely on pithy remarks about fly-snatching?

      • dave chamberlin says:

        Things have gotten worse with increasing popularity. My favorite blog is threatening to turn into a clown soup if someone doesn’t get blunt with idiots. Some of Cochran’s peers chastised our fearless leader a while back for ripping fools a new one, and I said NOOOOO, it’s the internet, it’s chock full of fools, and they will come here if we let them. You sir have a conundrum. You have a ton of research to do to write your next book. Don’t let this blog distract you. I said a very long time ago to you the world needs your books and it does. Give this zoo X hours and no more. Godspeed my friend.

      • panjoomby says:

        inspection time/reaction time correlates with IQ about -.4 or -.5-ish (from perusing Jensen’s research). wow.

        that’s about the same (absolute) correlation that spelling has with IQ (from perusing old BAS & DAS manuals).

        big deal. how is this different from comparing Victorian age spellers with modern spellers – make sure to get a full normal curve’s worth of each. oh, & better call it “spelling” instead of IQ. while you’re at it, check the correlation between spelling & reaction time – there’s another pub right there!

    • harpend says:

      Bruce: what does the distribution of reaction times look like?

      • @Henry – Well, I believe it is almost certain to be positively skewed when reaction times are fast on average – because of the physiological minimum; but becomes more symmetrical (normal) in slower average reaction times populations. But I haven’t actually seen the raw data from the Victorian studies, and Silverman only cited a median time for Galton’s results in his meta-analysis (perhaps indicative that the data was indeed significantly non-normal?). Put it this way, I would predict that the RT distribution becomes more positively-skewed (with a floor effect evident) as average reaction times become faster towards the ‘minimum’ of about 150ms. I don’t know, but maybe RT data from Ashkenazim might also show this skew?

      • @Henry – Here is a paper which has a distribution of simple RT Figure 1a

        Click to access 9c96051a468e9a56e9.pdf

        Very skewed, a lot slower than Victorian reported RTs.

        BTW – I don’t know how you can stand the comments on this blog – it’s like a bunch of 15 year olds who have just discovered sarcasm and learned a few swear words (and who enjoy being very *naughty boys*) – I would moderate and censor harshly if you want anything like rational discussion.

      • @Henry –

        BTW I get my 1 SD estimate of intelligence decline relative to modern IQ, not from a meta-analysis or curve-fitting, but from a very simple ‘assumption free’ method I employed here:


        This matches the value that Woodley et al got on much the same data in the Intelligence article the following year – but I have the most confidence in the cruder method.

    • dave chamberlin says:

      “IQ corresponds to a slowing of reaction times.” All this time wasted on all these complicated tests and all the while we should have been slapping people and see who could block it.

    • MC says:

      “(In a nutshell, I think Victorian English IQ was *about* the same or a little more than recent Ashkenazi IQ – but has declined.) ”

      Hmm…there are about 10 million Ashkenazi Jews alive today. There were about half again that many people in Victorian England at the time of Galton’s experiments, weren’t there?

      I know far too little about the history of mathematics to know how the accomplishments of Victorian mathematicians compare to those of present-day Ashkenazi, but it doesn’t sound crazy to me that they were comparable.

    • PF says:

      What? This doesn’t seem to require all those words. Unless I’m thinking of something else, the old studies sampled an elite group that wasn’t at all representative of greater “Victorian England.” If you test Oxford grad students today you’ll get similarly high results.

      Perhaps the level of discourse in popular culture could have dropped that much — but not IQ.

    • gcochran9 says:

      It’s nice that you like my work, but I wouldn’t put any stock in this thesis if I heard it from my own brother. The data is unreplicable and not known to be representative. The posited amount of change is implausible, given the time available and what we know of demographics. And your picture of the general state of the sciences seems fundamentally wrong.
      I shouldn’t have to explain this, but the biggest problem in physics is its success. Dirac said “The fundamental laws necessary for the mathematical treatment of a large part of physics and the whole of chemistry are thus completely known, and the difficulty lies only in the fact that application of these laws leads to equations that are too complex to be solved.” It is not so easy to come up with new, hugely creative solutions to problems that have already been solved to very high accuracy. When QED gives you the correct answer to 9 decimal places, further progress becomes relatively difficult. When Rutherford wanted to go beyond current knowledge,he could do it on a table top. The edge of knowledge is farther out now: if you want to look for effects that aren’t already explained accurately by existing theories, you must instead use the accelerator at CERN. Or, sometimes, you can still do it on the table top, but you nave to measure things a billion times more accurately than anyone did in 1900. Not so easy.

      There are still plenty of unsolved problems in physics, but most of the accessible ones are not fundamental in the sense that particle physics is fundamental. We keeping finding subtle, not-yet-understood quantum effects in condensed matter systems, like topological insulators, but we have every reason to think that those are complicated examples based on physical laws that are well understood.

      There were many good physicists and mathematicians in the Victorian era, but if they were smarter than people today, they were hiding their light under a bushel. I see no sign of it. I have never heard of anyone with expertise in the subject who does have such an impression.

      As for science in general – I know enough to have an opinion in some areas of math and physics, astronomy, optics, population and quantitative genetics, and evolutionary biology. In those areas, you’re just plain wrong.

      • JayMan says:

        The low-hanging fruit has just been picked. That’s how it is.

        But that reminds me of this:

        Futuristic Physicists? | Do the Math

        There are marked differences between physics undergrads and physics faculty in the likelihood each assigns to certain technological breakthroughs. Now, I grew up on Star Trek, but I have to admit that it’s unlikely that our future will ever feature warp drive, teleportation, or time travel.

      • @Greg

        I suppose there is nothing to be done about our different perception of the abundance of creative genius in modern science – you see it almost everywhere; but I see it almost nowhere.

        However when you say “The data is unreplicable and not known to be representative. ” I would first argue that Michael has shown that the data is sufficiently representative


        If the Victorian sample was not representative to any significant degree then there would be some significant attenuation of the size of difference when relevant controls were applied. But this didn’t happen – so modern and old samples *are* sufficiently similar.

        As for being un-replicable… well, obviously we can’t get any more historical data than exists – but after 18 months of brooding Michael and I came up with a way of checking (and, as it turned-out, confirming) the predicted size of the decline, details of which will be unveiled in due course…

        “The posited amount of change is implausible, given the time available and what we know of demographics.”

        But is it implausible? Only if you assume there is the single cause of differential reproductive success – but if other causes are also operating (such as the accumulation of intelligence-deleterious mutations due to the near-elimination of childhood mortality among the least intelligent) then the rapid rate of decline is *not* implausible.

        Despite the amount of ink spilled disagreeing with the 1SD size of intelligence decline – nobody has yet come-up with anything that refutes it.

        If 1SD decline in average intelligence was as absurd as you say it is, objective refutation should be easy and unambiguous – but seemingly it isn’t!

      • JayMan says:

        Bruce, let me simplify it for you:

        If you get a result that doesn’t make sense and goes against all other evidence in the matter, the odds overwhelmingly (though not absolutely) are that it’s wrong…

        • gcochran9 says:

          Like when Rasmus Nielsen was saying that the Tibetan altitude adaptations were all developed in the last 3000 years. I said that was obviously wrong, because the Tibetan adaptations worked so well compared to those in the Andes, and because humans of some sort had lived for much longer in Tibet than in the Andes. Nielsen seemed to think that it was somehow illegitimate to consider evidence other than the genetic sample he was looking at – but of course that’s not true. Any more than it is illegitimate to consider genetic facts when thinking about language dispersals. West seems to think that you must keep the evidence streams separate, but in fact, you must cross the streams.

          Or when the vast majority of human geneticists were really sure that anatomically modern humans had never admixed with Neanderthals, presumably because it was forbidden in Leviticus or something. Sure, we hadn’t seen any Neanderthal mtDNA, but that just means that one locus had a fitness disadvantage. We see lots of gene deserts in modern humans that are free of Neanderthal alleles – as well as ones in which they were neutral and around at a few percent, as well as ones which conferred an advantage and are common.

          Only this notion of Charlton’s is roughly a thousand times worse. To be fair, having a halfway decent picture of science in general is not so easy. Something as simple as the fact that science really doesn’t really exist at all in large parts of the world is apparently unknown by almost everybody, including people you might consider pretty smart. I remember having to explain this in annoyed detail to a closed list a few years back which had some fairly high-powered members.

          Now in people with no pretensions to being serious thinkers, that kind of ignorance is well-nigh universal. For example, I remember seeing somebody in the New York Times talk about how Idi Amin had ruined the great universities of Uganda – but of course there never were any ‘great’ universities in Uganda. I saw another such comment in Nature, where some dweeb explained that the insignificant research output of South American universities was the fault of the CIA, presumably before World War II as well, with the help of the time machine at Langley.

      • ursiform says:

        I used to work with a guy who once said he believed he could will the laws of physics to change. He advises the government on the acquisition of defense systems …

      • ursiform says:

        It hasn’t worked so far …

      • JayMan says:


        “There’s a lot of incorrect pessimism in that survey.”

        Interesting. How so, other than say timing? (It seems silly to me to project further than 500 years into the future.)

    • Douglas Knight says:

      Here is the scatterplot of mean reaction times in studies by year. I’m glad that the authors bothered to make a scatterplot, but I wished they had looked at it.

  14. I have just spotted a typo that got past my proofreading at the end of the fifth para (or first para of pint 1)

    This should read (as is made clear from the context and subsequent argument) “But I suggest that this would not be expected to have analogous functional consequences to a decline from 100 to 85, since IQ is not an interval scale.”

  15. little spoon says:

    Someone could study my group for these purposes. India has 6 science nobel laureates, 3 of which are Tamil Brahmins of the Iyer group. I think there are about 4.5 million Iyers. Another closely related group, Iyengar, which has about 600K members produced Ramanujan. I think the rate of winning science Nobels from this group is about the same as the typical European nationality.

    My group is interesting because we are the only entirely non European group that produces scientific geniuses at a comparable rate to Europeans. Asians have high average IQs, but they don’t produce the same frequency of creative genius. I think it would be interesting to see what features are common to Europeans and Iyer/Iyengars.

    • Greying Wanderer says:

      It does seem plausible that there would be Ashkenazi type sub-populations among India’s castes for the same sealed ecosystem type reasons.

      • gcochran9 says:

        Different from the Indian average, maybe. But there’s no evidence indicating that some Indian caste has an IQ as high as the Ashkenazi Jews. Actually, I’d like to see more evidence: is anyone aware of IQ results for different castes?

      • j3morecharacters says:

        Indian castes were solidified by the British for administrative purposes (in America, the Spanish also classified their subjects by castas.) Before and after the Raj, castes were open and fluid.

        • gcochran9 says:

          So fluid that, when we looked at their genes, it became apparent that there had been virtually no interbreeding between some castes – people living in the same villages – for thousands of years.

          “Allele frequency differences between groups in India are larger than in Europe, reflecting strong founder effects whose signatures have been maintained for thousands of years owing to endogamy.” – Reconstructing Indian Population History.

          All that stuff about the Brits imposing or solidifying caste in India is horseshit, typical sociologist dreck. There must be some legitimate role for such people, possibly as fast-food workers or in medical experimentation.

      • Matt says:

        The castes possibly were solidified by the British, the jatis weren’t.

        Meaning India has had a lot of disparate breeding groups for a while, but these groups may have risen and fallen on the status scale and occupational role, rather than had sustained long term pressure.

        The British may have frozen jatis into “caste” roles which they did not hold so much in their history – a scholar of caste history could comment on this (perhaps with a bit of Clarkish analysis). Where there were merely inbred families with no real caste role (but certainly family traditions of occupation), there became inbred families that were part of a formal caste.

        And before the British, high status jatis may have assortatively mated with one another less (and mated in-jati a bit more).

        • gcochran9 says:

          Only extreme endogamy can possibly explain the substantially different genetic composition of different castes. Even a little bit of intermarriage would have erased those differences over a fraction of the time available.

          If jatis often changed castes, Brahmins wouldn’t look they way they do, genetically.

    • aisaac says:

      I wonder what you’d get if you crossbred Iyers with Europeans or Ashkenazim. Presumably the genes that increase intelligence over that of their distant common ancestors are not all the same, so maybe you could get something better than either, with some luck and a ruthless eugenics program.

      I’d also want to give them a really cool name, analogous to “labradoodle.” Iyeuropean? Ashkebrahmim? Tremble before them!

  16. Gottlieb says:

    I think that when we talking about OUTLIERS, we talking about aleatority because to seems is a very general law of nature that you in a traditional way of reproduction where you have the equilibrium or you have the diversity and the best (or the worst). In indian castes wherever to seems that this dualistic natural mechanisms was changed by cultural-artificial way of reproduction and because of these selected and oriented historical (intragroup) reproduction could be turn them on both, equilibrated (without worst outliers types) and collectively to the best on specific and limited cognitive functions.
    Castes is like olympics but always with the costs.

    I see the lateralization like a one of the most important way of genetic aleatority (diversification of types) and like a repository of the mostly part of outliers. Therefore, mostly of the outliers tend to be non-right handed or with weak righ handed. Most outliers will find in ashkenazi than whites, in whites than asians, in mens than womens because this types are strongly influenced by aleatory epigenetic events.(higher exposure to testosterone) But, by quantitative and qualitative factors, the outliers will be more find in white caucasoid populations (or europopulations) but ashkenazi could be like a miniature of europeans, with same strong diversity of types but in a little population.
    To find the expected common traits of cognitive outlier you need find by
    a white man (or ashkenazi jew), non- stronger right handed with some behavior memes (weird or exccentricism) and particular subjetive disorders like stuttering or autistic traits. I believe the same happen to ”sport outliers” but less than last supposed traits.

  17. RS says:

    I don’t agree with Charleton’s view in any strong form, but Cochran needs to look at the diachronic population increase before pronouncing math to be flourishing, or non-collapsed.

    This is a per-capita thing we’re talking about.

    I say art has collapsed. Shakespeare, Tallis, the author of the Armada portrait, plus a bunch of lesser lights, were contemporaries in an England of four or five M people. There are now a billion Europids from among whom we might expect such work. Where’s it at?

    • dave chamberlin says:

      Where are the great composers to compare with what the German territories produced in one century in a population considerably less than Chicago metro? Where are the great artists Italy produced? Leonardo da Vinci and Michelangelo were born thirty years apart and fifty miles apart in rural Italy. Kind of lucky, don’t you think? Anyway my guess is Cochran’s main point was to educate the teeming masses on how an increase of a standard deviation in intelligence will multiply true genius. He has in past posts groused about the overall decline in intelligence lately so he gets it.

  18. Knoxy says:

    You are talking nonsense.

  19. Greying Wanderer says:

    “In another application – if the average genetic IQ potential had decreased by a standard deviation since Victorian times, the number of individuals with the ability to develop new, difficult, and interesting results in higher mathematics would have crashed, bring such developments to a screeching halt. Of course that has not happened.”

    Different populations though. Progress in mathematics has largely come to a screeching halt among the populations who had been leading the charge until recently.

    (Judging by the distribution map for the SLC gene and the existence of EDAR and skin lightening among East Asians I’d say another thing for the Chinese to consider researching before they get too poisoned by western ideas is how important breast-feeding is for brain development.)

  20. Greying Wanderer says:

    “False. You don’t know what you’re talking about. This happens a lot.”

    I work on the basis of the stuff I read here plus a little additional – possibly flawed – logic.

    1) I read here that currently mathematical progress is disproportionately Ashkenazi and Asian so I assume 100 ( or 200 or 300 or 400) years ago the proportion of mathematical progress from Euro populations was much higher than it is today.

    2) I read here that there’s been dysgenic breeding on IQ for some amount of generations. My understanding is you’re referring to the welfare system which is too recent for this but what if the industrial revolution had other effects?

    3) You say

    “You would also expect to see a vast over-representation in mathematics from a population with a significantly higher-than-average IQ, such as the Ashkenazi Jews – and again that is so.”

    So one possible logical explanation for the decline in the proportions of mathematical progress attributable to Euro populations would be a decline in the average IQ of those Euro populations.

    Maybe not 1SD but how would the proportions of Euro vs Ash/Asian furthest outliers shift with just a 5 point drop in Euro average IQ?

    (It’s not the only explanation obviously – another might be that once things get to a certain level only the furthest outliers can add to it.)

    • gcochran9 says:

      1. You probably didn’t read here anything that said that mathematical progress is disproportionately Asian because A. I never said it and B. it isn’t true.

      It is disproportionately Ashkenazi. But with current demographic trends, that’s likely to decline.

      2. I figure that serious dysgenic breeding is about 2.5 generations old, since it is mostly a function of women in higher education and careers.

      The simplest explanation for the “decline in the proportions of mathematical progress attributable to Euro populations” is that it hasn’t even happened. It might, if China gets vigorously into the game – but that has not yet happened.

      Here are the Fields medalists over the last 40 years:


      Enrico Bombieri
      David Mumford

      Pierre Deligne
      Charles Fefferman
      Grigory Margulis
      Daniel Quillen

      Alain Connes
      William Thurston
      Shing-Tung Yau

      Simon Donaldson
      Gerd Faltings
      Michael Freedman

      Vladimir Drinfeld
      Vaughan F. R. Jones
      Shigefumi Mori
      Edward Witten

      Jean Bougain
      Pierre-Louis Lions
      Jean-Christophe Yoccoz
      Efim Zelmanov

      Richard Borcherds
      Timothy Gowers
      Maxim Kontsevich
      Curtis T. Mcmullen

      Laurent Lafforgue
      Vladimir Voevodsky

      Andrei Okounov
      Grigori Perelman
      Terence Tao
      Wendelin Werner

      Elon Lindenstrauss
      Ngo Bao Chau
      Stanoslav Smirnov
      Cedric Villani

      One from China, one Chinese-Australian. One Kiwi, even though NZ’s population is a bit smaller than China’s.

      • Jim says:

        In the 19th century mathematics was virtually all European (including the overseas Europeans). The main change in the twentieth century consisted of important contributions from Japanese mathematicians and some Chinese and Indian mathematicians. The Japanese seem to produce important mathematicians at population rates comparable to European countries. Although there have been outstanding Chinese and Indian mathematicians (Chern and Harish-Chandra for example) their numbers are not as great as one might expect given the large populations of these countries. The European mathematicians include lots of Ahkenazi Jews and a few other exotics such as the Lebanese-Scottish Michael Atiyah or the Austrian Emil Artin who was partially of Armenian descent. There are sporadic contributions from the rest of the world such as the Mexican mathematician Jose Adem. However a tiny European country like Norway (pop. 5 million) has made far more contribution to mathematics (Abel, Lie, Skolem, Selberg etc.) than the entire globe outside European dominated countries, India and East Asia.

  21. Greying Wanderer says:

    “Breast feeding, in the 21st century developed world, is not that important for brain development.”


    “Controlling for a wide range of factors, children breastfed for four weeks or more do better than children breastfed for less than four weeks by about one tenth of a standard deviation (slightly less at younger ages, and slightly more at older ages). This loosely translates to a difference of about 3 IQ points.


    “We’re finding the difference in white matter growth is on the order of 20 to 30 percent, comparing the breastfed and the non-breastfed kids,”

    (nb just to be clear i’m not talking about 1SD type differences here but maybe 4-5 points.)

    • gcochran9 says:

      Which is why the bottle-fed baby boomers had such low scores – except that they didn’t.

    • misdreavus says:

      Worthless observational study. And no, multiple regression analysis doesn’t “control” for anything – it’s no better for establishing complex chains of causation than reading tea leaves.

    • dave chamberlin says:

      Look grey guy, evolution didn’t slight brain function in humans FOR ANYTHING. Half starve a poor bastard for half his life and he will be seriously stunted in size. But his brain will be just fine. So why would the tit make a big difference over the bottle, it doesn’t make any sense. These studies you are quoting are from laleche,org. Scientific based or ideology based, you tell me.

      • melendwyr says:

        “But his brain will be just fine.”

        Doesn’t that depend on the nature of the starvation? From what I recall, reducing calories leads to stunted growth but proper organ development. But if you reduce certain amino and fatty acids, brain development is seriously impaired.

      • dave chamberlin says:

        I respect your opinion melendwr. Does baby formula include these certain amino and fatty acids?

      • Sandgroper says:

        I think you can safely assume at this point that it is not a nutritional thing. Infant formula companies have studied the nutrition of human milk to death, including all of the amino and fatty acids. That is the easy part.

      • melendwyr says:

        dave chamberlin: “Does baby formula include these certain amino and fatty acids?”
        Now it does. It still can’t mimic the antibodies that nursing women share with their infants.

    • Sandgroper says:

      Surprisingly little work has been done on the biochemistry of human milk, mostly because this is the difficult end of science, and to do it you need someone really smart, good looking and with a really great Dad who is also smart and good looking.

    • Anthony says:

      Was one of those factors controlled for parental IQ? For quite a while now, breast-feeding has been more popular among better-educated and wealthier Americans, which means roughly more popular among higher-IQ Americans.

      • Sandgroper says:

        No, of course they didn’t. Look, we all know association studies are useless.

        Watch this: http://www.youtube.com/watch?v=AdRaBv1A3Mo

        If the effects of differences between breast feeding and bottle feeding were obvious, we would have noticed them, and we haven’t. This is all going to be a lot more subtle and nuanced.

      • Sandgroper says:

        “Consistent with a greater immunological need in the early postpartum period, colostrum contained considerable numbers of leukocytes (13–70% out of total cells) and high levels of immunoglobulins and lactoferrin. Within the first 1–2 weeks postpartum, leukocyte numbers decreased significantly to a low baseline level in mature breastmilk (0–2%) (P<0.001). This baseline level was maintained throughout lactation unless the mother and/or her infant became infected, when leukocyte numbers significantly increased up to 94% leukocytes out of total cells (P<0.001). Upon recovery from the infection, baseline values were restored."


        OK? That part seems pretty clear. My own idle thought is that may now be less important, with modern sanitation, health care and all. But what do I know?

        What is not at all clear is why human milk contains all those stem cells. Sometimes billions. It seems reasonable for Foteini Hassiotou to at least wonder if they serve some purpose, and if so, what. No one knows the answer, not yet.

      • melendwyr says:

        Sandgroper: “If the effects of differences between breast feeding and bottle feeding were obvious, we would have noticed them, and we haven’t.”

        The problem with that argument is that it presumes we’re not idiots. And when it comes to medical research, we are. It is remarkable how easily physicians can miss totally obvious things. Take Charles Bonnet Syndrome, for example. We used to ‘know’ that it was strongly associated with senile dementia. Turns out this extremely common condition was being concealed by normal patients because of the reaction honesty provoked, and only senile people lacked the awareness and restraint to lie about what they were seeing.
        Given how common CBS is, we’d expect countless physicians of all kinds – neurologists, opthalmologists, GPs etc. – to experience it as they aged. Yet they didn’t report it. It wasn’t until researchers started actively grilling patients – and not accepting their initial denials – that the true frequency was recognized.

      • Sandgroper says:

        I’m talking about population level things like a 1SD drop in mean IQ, or obviously higher rates of bottle fed babies suffering all kinds of obvious problems like serious infections. They don’t, not obviously.

      • Sandgroper says:

        Thanks for telling me about CBS, though, that’s interesting. Something to look forward to LOL.

      • melendwyr says:

        There are cases of more subtle effects going totally unnoticed. Try looking up the Extra-Intra Cranial Bypass. Then look up how long it took surgeons to recognize – and accept – that it increased the rates of death and debility among patients.

    • Toad says:

      Breast milk is loaded with saturated fats and cholesterol, it should count as a disadvantage.

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  23. rob says:

    If one were rich and low/high on conscientiousness, what could one do? My nightmare/dream conspiracy scenario is an American crypto-Darwin. Like Darwin with a little goatee. Someone from the landed Southern gentry. Someone fairly enthusiastic about artificial selection and natural philosophy. Someone who already saw some people as beasts in the field, and also practiced um …animal husbandry… with human cattle.

    I got the feeling that Cochran is hinting that we are ruled by an inbred aristocracy descended from Thomas Jefferson and a whole bunch of lucky ladies…

    But srsly Cochran, are hinting that there’s some small culture that’s been at this for a few generations? Or am I (just) crazy?

  24. Greying Wanderer says:


    “You would also expect to see a vast over-representation in mathematics from a population with a significantly higher-than-average IQ, such as the Ashkenazi Jews – and again that is so.”

    Has there always been that “vast over-representation?” If not then something changed.

    If something did change then it could be one of hundreds of things or a mixture of multiple small effects.

    If something did change then one possibility is the average IQ of the compared population has dropped.


    “Which is why the bottle-fed baby boomers had such low scores – except that they didn’t.”

    It’s your idea – or at least the idea that there’s some majorly important genetic advantage mirrored east-west where there’s no benefit from having both.


    @dave chamberlin

    “evolution didn’t slight brain function in humans FOR ANYTHING. Half starve a poor bastard for half his life and he will be seriously stunted in size. But his brain will be just fine. So why would the tit make a big difference”

    You just answered your own question.

    What are the most critical nodes: womb and breast-feeding.

  25. Jim says:

    Greg – But even in classical mechanics there is an enormous amount of stuff that is not understood. Long ago when I browsed through Siegel/Moser – Lectures on Celestial Mechanics or some title like that I was amazed at how little is know even about the 3-body problem. For example it is known when a triple collision will occur but the case of double collisions was not then resolved (this book was published back around 1948). They mentioned all kinds of open questions about the 3 body problem. As for the n-body problem for n greater than 3 they said almost nothing.

  26. Jim says:

    One difficulty for Norwegian mathematicians in the past was that there were few academic positions for the number of outstanding mathematicians the country produced. So for example Sylow spent almost his entire life teaching in the Norwegian equivalent of a US high school. Finally when Sylow was pretty old, about sixty or something, Lie retired from his position and recommended Sylow as his replacement. So Sylow finally got a university position.

    • Peter Lund says:

      You are mixing up different people, aren’t you?

      Sylow got his professorate in Kristinia (Oslo) 1898 but not because Lie retired from his Leipzig professorate in the same year (due to health problems — he died less than a year later).

  27. Jim says:

    Yes you’re right. Lie did recommend Sylow for an open position at Christiana University but Lie was not a professor there. But Sylow was 66 years old when he finally got a university position.

  28. Jim says:

    Selberg alone outshines the whole world outside of European, Indian and Chinese populations. The Selberg Trace Formula is mind boggling not just for it’s content but for what it hints at. Selberg developed this after he had received the Fields Medal.

  29. Arntor says:

    It’s a cliche, but the problem in Norway today is still the law of Jante, a pattern of group behaviour towards individuals that negatively portrays and criticises individual success and achievement as unworthy and inappropriate. Ivar Giæver said: Norway is a nice country, but you don’t participate in the contest, you talk about it.

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