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May 2, 2013 / JayMan

IQ and Death

In my previous post, I noted that the oft-mentioned association between obesity and poor health and “early” death may be a function of the lower average IQ of obese people. I suggested that the true correlate of these things was in fact low IQ. And indeed, I’ve stumbled on additional studies that suggests that this is in fact that case.

There are in fact many studies that look at the relationship between IQ and mortality. A 2011 meta-analysis by Catherine Calvin et al. corralled these to thoroughly examine this relationship. There is no doubt: higher IQ individuals live longer, on average, than lower IQ individuals do. This isn’t just from accidental death, but heart disease and other “natural” causes as well (but not cancer, I’ll soon return to this).

The studies in this analysis span many Western countries (Denmark, UK, USA, and Sweden) and collectively include well over 1 million subjects (mostly thanks to one Swedish study). They followed their subjects from a minimum of 17 years in some studies to a maximum of 69 years in the longest. IQ measured in childhood and early adulthood predicts mortality. Socioeconomic status (SES) in childhood doesn’t attenuate this relationship. Adult SES and educational attainment had at best only modest effects (34% and 54%, respectively). IQ alone stood as a predictor of mortality.

There are a few limitations. For one, ideally, the studies would follow the participants until they all, or mostly all died – and monitored the cause of death. After all, concerns about “healthy” behaviors obscure the fact that mortality rates are always eventually 100%. But, then we’d see the relationship between IQ and longevity all the way down. Obviously, such a study would be very difficult (impossible?) to do. One of the few that comes close is the Terman Life Cycle Study (“Terman’s Termites”) – which is analyzed in the paper.

The other limitation is the somewhat inconsistent measurements across these studies, which is common to most any meta-analysis. However, on that point, the largest of the studies, the Swedish conscripts study (N = 994,262) found similar findings (with the drawback that the subjects in this study were only followed for 20 years).

The consistency of the findings, especially in the largest studies (and even within race, as most of these studies were) shows the strong relationship between IQ and health. These may reflect “’Body system integrity’” (function of the neurologic system, which may correlate with function of other physiologic systems),” as the Swedish study put it. That is, mutational load and pleiotropic effects of these mutated genes coming to bear.

About the issue of the degree that the superior care higher IQ individuals take of themselves plays a role in this relationship, another study from Sweden (courtesy Staffan), which looked at 1 million military conscripts found NO association between IQ and cancer incidence (except for modest correlations with lung and skin cancers). Since behaviors, especially “healthy” ones are related to IQ, this suggest that behaviors have no effect on the incidence of most cancers. As Staffan put it:

It’s interesting because IQ is linked to lots of health behaviors. People love to think that health behaviors will fix everything but smart people eat their vegetables and get cancer anyway.

Indeed. This finding is interesting in its own right, because it suggests that the non-heritable contribution to cancer is essentially purely random. This weakens the case for adopting “the right, healthy behaviors” to ward-off unhealthy outcomes. Yet, none the less, that is the conventional wisdom – something which has not fared well around here.

As Staffan noted, the association between IQ and health can be attributed to behavioral patterns that differ by IQ. Quite likely that plays some role, but isn’t the primary, or perhaps not even a significant factor.

Edit, 5/13/13: [Also note that in this post, Kevin Mitchell comes to the same conclusion:

Various researchers have suggested that g may be simply an index of a general fitness factor – an indirect measure of the mutational load of an organism.  The idea is that, while we all carry hundreds of deleterious mutations, some of us carry more than others, or ones with more severe effects.  These effects in combination can degrade the biological systems of development and physiology in a general way, rendering them less robust and less able to generate our Platonic, ideal phenotype.  In this model, it is not the idea that specific mutations have specific effects on specific traits that matters so much – it is that the overall load cumulatively reduces fitness through effects at the systems level.

[...]

Direct evidence for this kind of effect of mutational load was found recently in a study by Ronald Yeo and colleagues, showing that the overall burden of rare copy number variants (deletions or duplications of segments of chromosomes) negatively predicts intelligence (r = -0.3).

If g really is an index of a general fitness factor, then it should be correlated with other indices of fitness.  This indeed appears to be the case.  G is weakly positively correlated with height, for example, and also strongly correlated with various measures of health and longevity.

[...]

This correlation can be interpreted in two ways: one, less intelligent people have less healthy and/or riskier lifestyles (i.e., direct causation), or, two, both intelligence and rates of mortality at least partially reflect an underlying factor – general fitness.

Another good marker of general fitness is developmental stability.  This refers to the robustness of the system and the ability of the genotype to reliably generate a phenotype within the species-specific normal range, despite genetic and environmental perturbations and intrinsic noise or randomness.  It is a property that varies between people.

One can get a good measure of developmental stability by looking at how symmetric someone is.  The two sides of the body develop independently from the same set of genomic instructions – if a particular genotype is very robust then it should generate a very similar outcome on each side of the body.  If, however, the system is less robust, then the person may be more asymmetric in any number of features (arm lengths, finger widths, earlobe lengths, eye widths, etc.).  This kind of asymmetry is called fluctuating asymmetry as the direction is random – one arm may be longer than the other, but it is equally likely to be the left or right (unlike the asymmetry of internal organs, for example, which is directional and a species-specific trait).

Fluctuating asymmetry should thus be a good indicator of general fitness and is fairly easy to measure (though it is important to look at multiple features to get an aggregate score in each individual).  It is also a heritable trait – monozygotic twins are more similar to each other in degree of asymmetry than are dizygotic twins.  There is no reason, however, to think this reflects variation in a set of genes whose function it is to make the organism more symmetric, or to make developmental systems more robust.  Rather, mutations in any genes affecting development are likely to not just contribute to some specific phenotype, but also to generally decrease robustness of the system and increase variability.

You can probably guess what’s coming next – fluctuating asymmetry correlates negatively with various IQ measures.  At least, most of the studies that have looked at it have found such a correlation – ranging from –0.2 to –0.4, which is fairly substantial.  Not all studies have found this but a meta-analysis confirms a correlation with a value between –0.12 and –0.2.  This correlation is weaker, but still significant, and means that there is at least some relationship between intelligence and symmetry.  (It may also be an underestimate, as one study found that psychometric tests with heavier loadings on g showed greater correlations with fluctuating asymmetry).  The most plausible interpretation is that this correlation reflects the effects on both parameters of a “latent variable” – general fitness.

This may, incidentally, also explain the recently demonstrated correlation between intelligence and physical attractiveness, which itself has been correlated with facial symmetry.]

EDIT, 2/4/14: Indeed, a new paper (co authored by Ian Deary) found that the same relationship, to the same degree, between IQ and longevity turns up when simple reaction time is used as the measure:

Reaction Time and Mortality from the Major Causes of Death: The NHANES-III Study

This strengthens the notion that intrinsic health – body system integrity (a bodily g factor if you will) – is in good part responsible for the IQ-longevity link.

What about proposition that the adverse outcomes associated with obesity might in fact be the result of low IQ? Well, fortunately, one of the studies in the Calvin meta analysis did take a look at that. The Vietnam Experience Study by Batty et al followed the outcomes of 4316 Vietnam War veterans, using their Armed Forces test scores upon entry into the military to gauge their IQ. The sample was subjected to a medical exam in 1986, which measured the subjects’ BMI, among many other things. The result: IQ was by far the strongest predictor of death. Indeed, “marital status, alcohol consumption, systolic and diastolic blood pressure, pulse rate, blood glucose, body mass index, psychiatric and somatic illness at medical examination) was negligible (10% attenuation in risk)!”

In other words, weight and other “common markers of health” had little to no effect on death rates of the subjects for the 15+ years they were followed after their exam in the 1980s.

Sure, we could (correctly) argue that these men were veterans and presumably had to have a modicum of physical and mental fitness to have served in the first place – hence, their results were unrepresentative of the general population. But, it’s hard to ignore a result that is quite consistent with my previous prediction on health, obesity and cardiovascular markers.

Putting all that I found and posted on this topic together, it would seem that the conventional wisdom – that we need to eat “right”, exercise, keep thin, etc., to live a long, healthy life is largely, if not entirely, bullshit. People who live long lives often do those things because they were healthier to begin with. It’s quite likely that a few (or more than a few) extra pounds won’t hurt you if you’re an otherwise all-around healthy (and mentally sharp) person.

Yet, people, including the medical establishment, continue to give this advice, (sometimes in spite of evidence). The reason? My own suspicion is that health advice is one of the last remaining straws of the Utopian wish to perfect man. Forced to let go (but not without great resistance) of the idea that we can socially engineer an end to poverty, war, strife, jealousy in a Star Trek-esque manner if we just try hard enough, and still coming to grips with the idea of cognitive and behavioral inequalities, Utopians have latched to idea that we can make people healthier and live longer (and of course, thinner) if we just adopt the right behaviors. It may turn out that much of that might not be possible even in principle (not via behaviors, anyway). A serenity moment if there ever was one.

Edit, 5/13/13: [Indeed, if ever there was a shining example of this, it would be this poor family:

Early heart disease ran in Rick Del Sontro’s family, and every time he went for a run, he was scared his heart would betray him. So he did all he could to improve his odds. He kept himself lean, stayed away from red meat, spurned cigarettes and exercised intensely, even completing an Ironman Triathlon.

Rick Del Sontro keeps himself lean and watches his diet, but despite his efforts, he has heart disease like many in his family.

“I had bought the dream: if you just do the right things and eat the right things, you will be O.K.,” said Mr. Del Sontro, whose cholesterol and blood pressure are reassuringly low.

But after his sister, just 47 years old, found out she had advanced heart disease, Mr. Del Sontro, then 43, and the president of Zippy Shell, a self-storage company, went to a cardiologist.

An X-ray of his arteries revealed the truth. Like his grandfather, his mother, his four brothers and two sisters, he had heart disease. (One brother, Michael, has not received a diagnosis of the disease.)]

As well, as noted, the anti-obesity people may have to come to terms with the notion that their crusade against obesity is more about aesthetics than health.

It is worth noting two pieces of evidence that may serve as counterarguments. There is a study of post-Soviet collapse Cuba that claims to have monitored marked declines in obesity and cardiovascular disease there for a time, only to rebound (at least obesity) after conditions improved. My impression is that, in this case, just as with sub-Saharan Africa, it’s hard to have weight problems when food is a scare commodity (smoking also greatly declined). As well, the authors admit to having problems with missing and unreliable data in their study. Nonetheless, there is it is.

Just the same, another study claims similar levels of good health for Victorian England. This study attributes the health of Victorian people to low salt consumption, lack of smoking and drinking, and much higher levels of (continuous) physical activity. The authors claim that degenerative diseases were generally absent in the day. On this one, I am doubtful because of the lack of anything resembling solid measurements and my lack of trust in the reliability of the diagnoses of 19th century doctors.

The field of health, going forward, is – contrary to what we might have thought about our time – rather wide open. There is much we still have to learn, a lot of it because of our reliance on poor research design and the failure to appreciate the power of heredity.

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46 Comments

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  1. AK / May 2 2013 5:21 PM

    You are right to be skeptical of that Victorian study. It is full of factual and basic conceptual errors and I am amazed that it was ever published.

    At 65, men could expect another ten years of life; and women another eight [24,32,33] (the lower figure for women reflects the high danger of death in childbirth, mainly from causes unrelated to malnutrition). This compares surprisingly favourably with today’s figures: life expectancy at birth (reflecting our improved standards of neo-natal care) averages 75.9 years (men) and 81.3 years (women);

    This, for example, which contains two howling errors, betrays the authors’ profound lack of understanding about basic demography and disqualify them from seriously writing about it.

    • Toddy Cat / May 16 2013 12:16 PM

      Yes, and it was obvious. I mean lack of drinking in Victorian England? Really? REALLY?!?

  2. Stakhanovite / May 2 2013 5:23 PM

    Let’s say you’re right and there is a link, it would certainly provide an interesting debate on the future of healthcare. As an example, in those countries without universal health-care, would an officially-recorded IQ start to influence how much you pay on your premium?

    • JayMan / May 2 2013 5:27 PM

      In the developed world, that’s the United States, right? I don’t know how well the pattern holds for non-Europeans (I’d imagine it does hold). I guess this is an argument for universal healthcare.

    • JayMan / May 2 2013 5:39 PM

      With some real end-of-life Conversations at that:

      How Not to Die – Jonathan Rauch – The Atlantic

  3. Stakhanovite / May 2 2013 5:53 PM

    Aye I suppose the USA is the main example. Of course it could be argued both ways…some might say if you’re highly likely to die of a number of things, and your IQ is so low you’re not likely to make any worthwhile contribution to society, then why should everyone else support you and keep you alive for a few more frivolous years? Very cruel world sometimes.

    Oh and thanks for the article there, reminds me a wee bit of ‘A Social History of Dying’ by Allan Kellehear.

  4. Ed the Department Head / May 2 2013 9:59 PM

    Good post! I agree that I think it is a utopian fantasy that weight is going to be kept in BMI correct portions in the modern era. It shocks me how many people who follow HBD and understand human limitations in other fields suddenly sound like nurture based egalitarians when questions of weight and diet come up. I suspect if there is to be a reduction in weight among the general American population in the future it will come from something like mimAB1 or beloranib and not constant starvation diets.

  5. Amber / May 3 2013 4:14 AM

    It’s my personal observation that high-IQ people develop more slowly, physically/social-maturity-speaking. They are children longer, they hit puberty later, etc. So it is not surprising that they would die later, too. I’ve read (probably here) that higher-IQ populations have longer gestations. It all adds up to more time for brain development. (By implication, then, environments which encourage high fertility would depress IQ because early adolescence would limit brain development.)

    The smart kids end up socially “behind”, smaller than their peers, and too smart for the material being taught. Poor kids!

    • Staffan / May 3 2013 6:48 AM

      Human civilization with its safer environment creates an opportunity for people to stay more childlike, which increases crystallized intelligence. That is, the more civilized a society is, the more advantageous neoteny becomes. And since the level of civilization is almost by definition a matter of intelligence, this means that neoteny is a way for smart people to get even smarter. (Just speculating a little here.)

    • szopeno / May 6 2013 4:05 AM

      There could be something about it – definetely I matured much, much later than many of my less gifted friends. Moreover, males height is rising only up to 20s, right? I was 179 at 18, 181 at 30, and NOW I am 182 meaning I have raised another cm AFTER 30, clearly impossible, right? And people claim I look as if I was ten years younger …

    • Anonymous / May 14 2013 3:05 PM

      Staffan, “Human civilization with its safer environment creates an opportunity for people to stay more childlike, which increases crystallized intelligence. That is, the more civilized a society is, the more advantageous neoteny becomes. And since the level of civilization is almost by definition a matter of intelligence, this means that neoteny is a way for smart people to get even smarter. (Just speculating a little here.)”

      Then the US is in trouble because I find kids here to be sexually maturing earlier and earlier.

  6. panjoomby / May 3 2013 9:38 PM

    “…it would seem that the conventional wisdom – that we need to eat “right”, exercise, keep thin, etc., to live a long, healthy life is …BS.” amen, Jay-buddy! wonder if there are data from twin studies re: whether the higher-IQ twin lived longer… to get more out of that data with mainly Nordic-European stock, throw in some australian aborigines, etc. the more variability in that data, the stronger the relationship between IQ & age. hmm, then we could compute stats such as a “140″ can smoke a pack a day & live to be the same age as a “125.”

    • JayMan / May 3 2013 10:17 PM

      Very good point! I will look and see of there are sibling studies. I’d imagine the data can easily be extracted from the Swedish conscript study, as there must be many brothers in the sample…

  7. Saddam Hussein's Whirling Aluminium Tubes / May 5 2013 11:18 AM

    It’s a good point with some validity, but it doesn’t explain everything.

    Romania has an average IQ of 94, but it is the EU’s slimmest nation.

    The UK has an average IQ of 100, but it is the EU’s fattest nation.

    http://www.romania-insider.com/eu-obesity-report-slim-trim-romania-big-fat-britain/41647/

    My thought is that functional traditions can take much of the burden of thinking away from the lower IQ segments of the population.

    If a society is traditional with regard to a certain life decision and that tradition is beneficial, then the masses will tend to default to beneficial behaviour.

    If a society has no tradition or weak tradition with regard to a certain life decision, then the masses will have to make their own decisions, with disastrous consequences. The cognitive elite will be better able to handle this added complexity. (They still make a lot of mistakes though.)

    If a society is traditional with regard to a certain life decision and that tradition is harmful (“traditional American cuisine”), then the masses will tend to default to harmful behaviour. (Pizza and burgers every day) The cognitive elite will be better able to identify and avoid these harmful behaviour patterns. (Eat a salad).

    This applies to other life decisions, like marriage. A large marriage gap is developing between the masses and the cognitive elites. Although in that case there are obvious cheater strategies that some segments of the masses can adopt.

    Of course, this is oversimplified, as it ignores the role of the cognitive elite in destroying traditions, creating a situation where the cognitive elite can thrive (or at least do alright) while the masses really, really struggle to make their own decisions.

    • JayMan / May 5 2013 11:29 AM

      It’s a good point with some validity, but it doesn’t explain everything.

      Romania has an average IQ of 94, but it is the EU’s slimmest nation.

      The UK has an average IQ of 100, but it is the EU’s fattest nation.

      http://www.romania-insider.com/eu-obesity-report-slim-trim-romania-big-fat-britain/41647/

      I don’t think IQ explains much of the difference between groups, but it probably explains a lot of the difference within groups.

      For more on regional differences in body weight, see here:

      A Fat World – With a Fat Secret? | JayMan’s Blog

      My thought is that functional traditions can take much of the burden of thinking away from the lower IQ segments of the population.

      If a society is traditional with regard to a certain life decision and that tradition is beneficial, then the masses will tend to default to beneficial behaviour.

      If a society has no tradition or weak tradition with regard to a certain life decision, then the masses will have to make their own decisions, with disastrous consequences. The cognitive elite will be better able to handle this added complexity. (They still make a lot of mistakes though.)

      This echoes something Peter Frost recently wrote. While it probably plays some of a role in obesity, I don’t think it plays much. Genetic propensity (both in terms of metabolism and junk food addictive potential) is probably the overwhelming factor.

    • JayMan / May 5 2013 11:42 AM

      BTW, it’s worth noting that cardiovascular disease (CVD) risk is largely flipped between Western and Eastern Europeans with respect to obesity: CVD increases as you go from SW to NE in Europe. See:

      A Fat Problem With Heart Health Wisdom « JayMan’s Blog

      and

      And Yet Another Tale of Two Maps | JayMan’s Blog

      In other words, the thinnest Europeans aren’t necessarily the healthiest.

    • Saddam Hussein's Whirling Aluminium Tubes / May 5 2013 11:54 AM

      I think the points you raise play a role, but on the other hand, the Anglo-American populations that currently suffer from high levels of obesity were much thinner only 50 years ago. They could have afforded fattening food back then, if they’d really wanted it. The genes haven’t changed, but the environment has.

    • JayMan / May 5 2013 4:50 PM

      Fattening foods (modern junk food) largely didn’t exist back then. As well, the much higher rate of smoking could have been keeping people thinner.

      That said, you are correct. The environment did change. The relevant questions are can we change it to one where people are thinner, and if yes, how?

    • Anthony / May 14 2013 6:53 PM

      Malnutrition depresses IQ, and most adults in Romania spent some of their lives under Communism, which wasn’t always so good at keeping its subjects fed. Romania is *still* poor, and food is expensive relative to incomes, so Romanians are less *able* to get fat despite any greater propensity to fatness.

    • JayMan / May 14 2013 9:54 PM

      Perhaps. I’m not sure that’s the explanatory variable in Eastern Europe. But, Belarus does seem to be an outlier there for some reason. They also claim to have very low unemployment…

  8. Renfrow / May 9 2013 9:19 AM

    Some anti-HBD, anti-manosphere genetic denialist nonsense by Mark Manson, ex-PUA. The kind of stuff you specialize in debunking. Check it out:

    http://postmasculine.com/the-biology-bias

    • Anonymous / May 14 2013 3:09 PM

      I clicked on the link and nothing he wrote was debunkable;

      “In psychology, there’s a well-observed phenomenon known as the actor/observer bias and it states that we’re basically all a bunch of assholes.

      The actor/observer bias states that all of us unconsciously assume others to be more responsible for their negative actions than their environment, and for ourselves to be less responsible for our negative actions than our environment.

      For example, if you are at an intersection and someone runs through the red light and almost hits you, you think, “Wow, what a shitty driver. That guy is an idiot.” But when it’s YOU who runs the red light and almost hits somebody, you think, “It’s not my fault. The guy in front of me was driving slow and the light changed too quickly for me to stop.”

      When it’s us, it’s not our fault. When it’s someone else, they’re a shitty person.

      But it gets worse. The opposite happens with positive actions, too. In our own case, we over-estimate our own responsibility for the great things we do and under-estimate the responsibility of others. For example, if someone else wins a prestigious award, we make assumptions that they got it because of their connections or some sort of conspiracy and not of their own work. But if we win an award, we assume it was all because of the great work we did.

      The actor/observer is a natural bias that afflicts us all. We can be mindful and try to be better about it, but we’re never completely rid of it. ”

      ….. The rest of his article is similarly not debunkable. We are a combination of nature and nurture. Otherwise there would be no point to education or culture at all. All we should just do then is be born, exist, and let chips fall where they may. Which is not what humans do.

  9. Dan / May 15 2013 5:17 PM

    I don’t buy the link between IQ and ‘genetic load’ at all, for many reasons.

    (1) What is ‘genetic load’ anyway? It is not even defined properly. It is described vaguely as ‘deleterious mutations’ but what is deleterious depends on circumstances. A big brain could be a deleterious mutation if you live a hot climate where big brains lead to heatstoke or if it has big caloric requirements or causes your mom to die in labor. Or it could be an absolute necessity if you happen to be a member of the banking caste in middle ages Europe.

    (2) I just don’t see generally greater health in high-IQ types. Lots of smart people I know are nearsighted, lanky, or physically uncoordinated. Meanwhile, lots of top athletes, the pictures of genetic fitness, fill remedial classes and need tons of tutors to get through the easiest majors at their universities.

    (3) Jews are generally agreed to have a higher average IQ than other groups. And they also have a whole host of genetic diseases not common to other groups:
    http://www.jewishgenetics.org/?q=content/what-are-jewish-genetic-disorders

    There have been tons of Jewish Nobel laureates but very few Olympic champions, even though the former is more rarified.

    (4) It’s possible to be extraordinarily well adapted and not have a high IQ. IQ is emphatically not the measure of fitness for most creatures and most creatures do not even try to have a high IQ. A hypothically genetically perfect creature may be naturally dumb. It seems clear that to me that this variation in what the target even is applies to different humans and human groups too.

    (5) Hispanics in America have a considerably longer life expectancy than whites.

    Why, then do high IQ types live longer? Many reasons, all added up. They will do a better job avoiding danger, finding good living conditions, staying active and more. ‘Genetic load’ is not the explanation.

    • JayMan / May 15 2013 9:49 PM

      You raise some interesting points.

      What is ‘genetic load’ anyway? It is not even defined properly. It is described vaguely as ‘deleterious mutations’ but what is deleterious depends on circumstances.

      Yes, whether a mutation is “deleterious” is generally dependent on the environment. That said, there many mutations that would be always negative, regardless. Clearly, anything that causes death (especially before reproduction) or interferes with major systems would be deleterious in any environment. But even milder mutations are likely to be generally negative for the simple reasons that there are many more ways of screwing something up than making it better.

      I just don’t see generally greater health in high-IQ types. Lots of smart people I know are nearsighted, lanky, or physically uncoordinated.

      Manwho much? IQ is correlated with health, not commensurate with it. One good manwho deserves another, what about Richard Lynn, James Watson, or even the late Arthur Jensen? Many brainy folks live to a ripe old age with minimal sign of impairment. The above studies show a clear positive relationship between IQ and health.

      Meanwhile, lots of top athletes, the pictures of genetic fitness, fill remedial classes and need tons of tutors to get through the easiest majors at their universities.

      Are we talking within race, or between them? Genetic load is probably responsible primarily for within race variance. Between race variance is largely another matter. But indeed, there is evidence that athletes die earlier than others, so just how healthy are they?

      Jews are generally agreed to have a higher average IQ than other groups. And they also have a whole host of genetic diseases not common to other groups

      Ashkenazis recently went through fairly intense selection for intelligence. That probably promoted a whole host of sub-optimal “quick fix” IQ-boosting genes. That said, a good question is are more intelligent Jews healthier, overall, than less intelligent ones?

      It’s possible to be extraordinarily well adapted and not have a high IQ. IQ is emphatically not the measure of fitness for most creatures and most creatures do not even try to have a high IQ. A hypothically genetically perfect creature may be naturally dumb. It seems clear that to me that this variation in what the target even is applies to different humans and human groups too.

      You’re probably quite correct. Razib Khan raised a similar point. In general, I suspect genetic load is a part of the story with health, not the whole story. But thinking of IQ as a measure of general fitness is a fairly good approximation.

      Hispanics in America have a considerably longer life expectancy than whites.

      This may very well be thanks to their Iberian component. Southwestern Europeans are known for longevity. An interesting question on this matter is how Latin American lifespans compare to their source populations’.

      Why, then do high IQ types live longer? Many reasons, all added up. They will do a better job avoiding danger, finding good living conditions, staying active and more. ‘Genetic load’ is not the explanation.

      I think it’s clear at this point that you can’t make that declaration. There is evidence that suggests that the longer life of higher-IQ people isn’t just due to better self-care, as noted above.

    • Dan / May 16 2013 9:52 AM

      Thanks for the thoughtful reply.

      I might have more thoughts but here are few for now…

      (1) First I will concede that genetic load does have *some* explanatory power, in the sense of broadly debilitating things such as Down’s Syndrome and a few others. But I think most genetic defects are not syndromic like that.

      (2) Good prenatal and childhood nutrition have large positive effects on both IQ and lifelong health. Folks like Richard Lynn, James Watson, or Arthur Jensen would certainly have had good prenatal and childhood nutrition.
      http://www.ncbi.nlm.nih.gov/pubmed/11244286

      (3) People who are nearsighted (a clear defect) are on average *substantially* more intelligent that their non-nearsighted peers. The reasons are not known, but the stereotype is true.
      http://blog.zennioptical.com/are-people-with-nearsightedness-smarter/

      which leads me to

      (4) I would theorize that high IQ types can actually tolerate a *higher* genetic load. If I am a 98 pound weakling who gets sick a lot but who has a high IQ, I will probably manage just fine. There are lots of things I can do. If I am a 98 pound weakling who gets sick a lot and is also not that smart, there is not a lot I can do and there is not a lot that is a attractive about me. Stephen Hawking would have died of neglect in a care facility decades ago if he wasn’t smart.
      http://4.bp.blogspot.com/_GsUl3_1ezpI/S_S45B31mPI/AAAAAAAAAGA/3UKCUfJmwbI/s1600/stephen-hawking.jpg

      I would make a Dungeons and Dragons analogy.
      http://en.wikipedia.org/wiki/Dungeons_%26_Dragons_gameplay#Ability_scores

      The fitness of a player is based on scores in a number of categories. Surely someone who has excellent intelligence, wisdom and charisma needs a lot less of the other things (strength, dexterity and constitution/health) to do well whereas someone who is poor in these categories needs a lot more of the other things to get by.

      I wouldn’t be surprised if people ultimately discover that high IQ types actually have more genetic load on average, although I repeat that I don’t quite know what I mean by genetic load since it is so situational. Heck, Hawking’s condition, which looks like a horrible defect from all angles, has been an overwhelming positive for his career and his fame.

    • JayMan / May 16 2013 10:22 AM

      Good prenatal and childhood nutrition have large positive effects on both IQ and lifelong health. Folks like Richard Lynn, James Watson, or Arthur Jensen would certainly have had good prenatal and childhood nutrition.

      Where these things matter at all, I’d suspect it’s in a mostly negative sense; you can be harmed if you don’t get an adequate supply, but you almost certainly won’t be helped by anything that goes past your minimum baseline. Most people in developed countries receive well past that baseline.

      People who are nearsighted (a clear defect) are on average *substantially* more intelligent that their non-nearsighted peers. The reasons are not known, but the stereotype is true.

      Myopia is more like those Ashkenazi diseases. It boosts your IQ but represents a trade-off between increased performance in one area at the cost of decreased performance elsewhere. To people in civilized societies, poor distance vision wouldn’t have been as big as a fitness hit as it would be to say a hunter-gatherer.

      I would theorize that high IQ types can actually tolerate a *higher* genetic load. If I am a 98 pound weakling who gets sick a lot but who has a high IQ, I will probably manage just fine.

      I’d say probably not. That smart 98 lb weakling would be fine today. In pre-modern times, not so much.

      I wouldn’t be surprised if people ultimately discover that high IQ types actually have more genetic load on average, although I repeat that I don’t quite know what I mean by genetic load since it is so situational.

      This is pretty much impossible. The brain, being the place where most genes are expressed, is the biggest mutational target. IQ, being highly polygenic, would be quite easy to screw up with deleterious mutations. There is evidence that indicates lower IQ is correlated with a host of diseases and fitness hits, including, as noted in the post, reduced symmetry, indicating higher levels of mutational load in the low-IQ.

    • Dan / May 16 2013 12:05 PM

      “That smart 98 lb weakling would be fine today. In pre-modern times, not so much.”

      That smart 98 lb weakling probably could have done fine as a craftsman or scholar or financier or trader or range of other professions that would have existed over the last 800 years in England or other places.

    • Dan / May 16 2013 1:19 PM

      ” The brain, being the place where most genes are expressed, is the biggest mutational target.”

      Is this true? Is it true that a majority of genes are involved with the brain? Certainly genes that relate to things like metabolism or the immune system could indirectly affect the brain, but does the brain really express ‘most genes’?

      Do you have evidence for this statement (links are great!), because if it is true I suppose I’d have to concede a lot of the argument.

    • JayMan / May 16 2013 1:46 PM

      See here.

    • Dan / May 16 2013 3:17 PM

      Yes, Trivers does suggest that possibility in his book, doesn’t he? Good point.

      Trivers doesn’t cite any scientific source in that book, but then again he is a giant in his field, and he surely knows a bit about the topic.

  10. Soxy / May 16 2013 8:51 AM

    If high iq people live longer than low iq people,can it reduce the effect of dysgenics on society.

  11. panjoomby / May 18 2013 4:02 PM

    thank you for your blog & your empirical insights – & for your comments at other blogs – e.g., your comments at http://www.wiringthebrain.com/2013/05/the-new-eugenics-same-as-old-eugenics.html
    are WAY better than the article! your blog conversations with hbdchick are casually brilliant. i hope someday there will be an HBD blog convention. i had paypal tell you hi – wish it could be for more – you HBD bloggers deserve it.

    • JayMan / May 18 2013 6:38 PM

      Thank you, I greatly appreciate it!

  12. Steve Sailer / Jun 1 2013 12:04 AM

    A good very long term study is Ian Deary’s follow-ups to the 1932 Scotland testing of all 11-year-olds in the realm.

    • JayMan / Jun 7 2013 3:13 PM

      Thanks! I saw that, it was one of the studies in the Calvin meta-analysis. It was one of the studies that reported a stronger association between IQ and earlier death. There wasn’t a huge amount of spread in the studies though, so the pattern is pretty solid.

  13. Steve Sailer / Jun 1 2013 12:07 AM

    It would be interesting to disentangle intelligence and conscientiousness, which tend to get wrapped together in low-stakes cognitive testing where the conscientious people work harder on the test because they’ve been told to work hard by legitimate authority figures. I think some of the predictive power of IQ testing comes from measuring willingness to work hard.

    • JayMan / Jun 7 2013 3:14 PM

      I agree. I believe there was a study that did just that. Another project of mine will be to look at the correlates of mortality with IQ and personality combined.

  14. Travis / Jun 4 2013 6:02 PM

    So stuffing myself with Cheetos and Coke every day will not raise the probability that I will get adult-onset diabetes?

    As much as I like the sound of that, I suspect it is not true.

    • JayMan / Jun 4 2013 6:04 PM

      I didn’t say that in the post. I suspect that diet does influence the incidence of diabetes for people with a genetic susceptibility to it…

  15. Greying Wanderer / Jun 9 2013 8:23 PM

    Dan
    “I don’t buy the link between IQ and ‘genetic load’ at all, for many reasons.

    (3) Jews are generally agreed to have a higher average IQ than other groups. And they also have a whole host of genetic diseases not common to other groups:
    http://www.jewishgenetics.org/?q=content/what-are-jewish-genetic-disorders

    I think there are two ways to raise average IQ.

    1) Select specifically on IQ which by definiton means you’re not selecting as strongly on things like health. A population that did this *ought* to have higher IQ and lower average health.

    2) Select on general fitness. This will include IQ alongside, health, symmetric looks, height etc.

    The correlation between IQ and health might still partially exist for option 1 simply because brain function involves such a lot of genes but ought to be substantially higher for populations who’d undergone the second type of selection (which i think is provided by the northwest european marriage model).

    http://en.wikipedia.org/wiki/Hajnal_line

  16. franklindmadoff / Feb 4 2014 5:23 PM

    Jayman,

    You may want to check out this study: “Reaction Time and Mortality from the Major Causes of Death: The NHANES-III Study”

    http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0082959

    “Adjusted for age, sex, and ethnic minority status, a 1 SD slower reaction time was associated with a raised risk of mortality from all-causes (HR = 1.25, 95% CI 1.12, 1.39) and cardiovascular disease (CVD) (HR = 1.36, 95% CI 1.17, 1.58). Having 1 SD more variable reaction time was also associated with greater risk of all-cause (HR = 1.36, 95% CI 1.19, 1.55) and CVD (HR = 1.50, 95% CI 1.33, 1.70) mortality. No associations were observed for cancer mortality. The magnitude of the relationships was comparable in size to established risk factors in this dataset, such as smoking.”

    • JayMan / Feb 4 2014 5:59 PM

      @franklindmadoff:

      Yup, Mangan tweeted it. Of course, Mangan’s explanation was that reaction time was some marker of physical conditioning training, when the paper itself discusses the known association between IQ and longevity. It’s just another for the pile… ;)

      Thanks for linking to it!

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