Imagine that there is a trait observed among people that seems to occur more frequently in some families and not others. One might suspect that the trait is inherited genetically. Imagine researchers looking for the genetic underpinning of this trait and at first, not finding it. What might you conclude? It could be reasonable to conclude that the genetic underpinning of the trait is elusive, perhaps complicated with multiple genes, or that there is a non-genetic component, also not yet identified, that makes finding the genetic component harder. Eventually, you might assume, the gene will be found.

That is probably true sometimes. But we have sequenced the entire human genome, so shouldn’t we know about all the genes? Well, yes and no. We may have a list of genes found in a sample of humans, but “The Human Genome” can consist of a single individual (though it does not) and miss variation between individuals, i.e., it may not be a record of all of the possible alleles (variants) of each gene. Also, beyond the scope of this discussion but worth mentioning, a “gene” is not a simple concept. Whether or not a gene is expressed, where, when, and exactly what product it produces is not entirely encoded in the gene itself, but rather, elsewhere in the genome, or not encoded at all, but rather, dependent on external, non-genetic factors. So that complicates things too. So, if there is a trait that you think must be genetic, but years of research have failed to find it, the existence of a human genome and the prior acquisition of a lot of genetic data does not necessarily mean that the genetic information that determines the trait in question is not there. You can continue to believe that the genetic code for the trait will eventually be found

Except when you can’t.

There are two separate ways in which people sort out which traits are assumed to be genetic from those that are assumed to be not genetic. Both are heuristic, one is valid, and one is not. Let’s start with the one that is valid.

Suppose, as before, there is a trait that is seemingly inherited in families in such a way that a genetic trait would be, in the time tested manner that with respect this trait “offspring resemble their parents” as Darwin noted. The next question you can ask is this: Is it biologically sensible that this trait is inherited genetically, or is there a better, obvious, non-genetic mode of inheritance? If the trait is a physical feature such as eye color, then we have a sensible biological explanation for the trait having to do with developmental process we know something about and a set of metabolic pathways that produce various molecules such as pigments. The idea that this trait is genetic is biologically sensible, so even if you can’t find any, or all, of the genetic determinants of this trait, you can figure they are out there somewhere. Suppose, though, that the trait is a behavioral one that we see people in real life learning. For example, what language a person speaks generally follows the same kind of inheritance pattern many clearly genetic traits follow. With respect to spoken language, most of the time, offspring resemble their parents. But, rather than there being a sensible biological explanation for this trait, there is a sensible cultural explanation for this trait, so we don’t even look for the genetic variants for “French” vs. “Mandarin” vs. “English.” We simply assume this is not genetic.

The second method, the incorrect one, is to work with an article of faith. Broadly speaking, and I oversimplify greatly here, there are two primary articles of faith that often inform people’s thinking, shaping their assumptions, about genetics. Both usually have to do with behavioral traits in humans, but this can apply to physical traits as well. One article of faith asserts that humans are born as a blank slate, and all of their behavioral characteristics, such as their personality, intelligence by one measure or another, and so on, are added by experience. The other is the inheritance assumption, that some or much of an individual’s personality, intelligence, etc is determined by genes. There is not necessarily a consistent logic behind either of these assumptions, though various schools of thinking will include, often, a logical framework. However, this method of coming to a conclusion about the genetics or lack thereof behind various traits relies on one important element regarding genetic systems: Ignorance. If you are a blank slatist, then the absence of a clear pathway from genes to behavior means that your hypothesis can’t be falsified. If you are a genetic determinist, then the lack of such a pathway can be attributed to ongoing ignorance about the genes. The former might then be expected to live in fear that a gene will be found for their favorite learned behavior, and the latter might be expected to to live in a state of hubris, firmly knowing and asserting a truth that is not yet known but someday will be.

My impression is that over time there are fewer and fewer pure genetic determinists out there, and few and fewer blank slatists. I think the reasons for that shift have little to do with increasing knowledge, and more to do with changes in how one plays the academic game of argument, but that is discussion for another time. There is a danger in that shift, though. In the absence of any useful research results, if blank slatists start to admit that there could be some sort of genetics behind behavior, and determinists start to admit that experience and learning can also play a role, then we are converging on an increasingly simplified view of what is really a very complicated process. We should be gaining more complex, nuanced, and better informed views of how behavior arises, not simpler ones. Probably.

Over the last few decades, there have been a few important changes in how we should view human behavior over generational time and variation in those behaviors within and across categories (gender, ethnicity, geography, etc.). In short, certain behavioral traits have shown, synchronically (lacking the perspective of change over time) patterns that look genetic. For example, some families seem to be extra smart. Some have suggested that some “races” are smarter than others (at another time we can discuss why there really are no races, but let’s use “race” here as a potentially valid sampling strategy, which it can be even if the underlying races are fictions). We also see assertions of behavioral differences between the primary sexes (male vs female).

These observations are really statements about variance. Two groups are different, but vary within. There is overlap in the trait (i.e., IQ) but the means vary. We can statistically test the validity of the asserted differences in means by examining the variance in each sample and seeing if the mean of one sample fall within the predicted range of the central tendency of the others. In other words, asserting that there is a statistical difference between two groups is a process that involves understanding the variance of the underlying population(s) and samples. So, the questions can all be reframed in this manner:

Is the variation we see in trait X across certain groups best explained by underlying corresponding variation in the genetic system, or by the variation found in some other cause?

People fight vigorously over the underlying cause of IQ differences between groups. Some say it is primarily genetic, some say it is primarily not genetic, but rather, related somehow to what has become known as “lived experience.” Over the last couple of decades, there have been many attempts to explain observed variation in IQ using socioeconomic status, diet, education, issues having to do with test making or testing procedures. All of these factors have been shown to explain differences between groups to a modest to large degree in several studies. In other words, if you want to explain variation in IQ using non-genetic explanations, you can have some real success.

The genetic explanation of variation in IQ has had success in one main area which is irrelevant. This is the fact that genetically determined developmental differences between people that affect function that are generally classified as disorders predict large IQ differences. But this set of effects is not related to the question being asked.

The strongest evidence for a genetic underpinning of IQ is probably the large scale racial model solidified years ago by J. Philippe Rushton. He demonstrated that there is a grouping of brain sizes by race, with Asians having the largest brains, Caucasians the second larges, and Blacks the smallest (these race terms are his). He then showed that these brain sizes correlated with IQ difference. The modern psychometric literature assumes a racial difference in IQs, and asserts that this difference is real, but does to by citing sources that then site sources that ultimately cite Rushton. Rushtons all the way down, as it were.

The problem with this is that Rushton’s analysis was bogus. The brain sizes were taken from such sources at hat sizes for army conscripts classified by race, with the hat sizes used to estimate brain size. The Black (African) brain got smaller because Rushton subtracted a factor from that estimate of brain size, using an archaic thick skulled African fossil to assume that Africans have very very thick skulls. Correspondingly, the Asians were assumed to have thin skulls, and thus, got larger brains. The IQ data is similarly adulterated. In one part of the study, Rushton needed an “African” (native) IQ value, so he used the results of a test administered by racist anthropologists commissioned by the Apartheid government of South Africa to prove the inferiority of Blacks. And so on. The bottom turtle in this edifice is a fake.

The range of variation across “racial” groups (or other groups) in modern IQ data is very small compared to the change in IQ measured or estimated over decades of time through the 20th century within a single large and diverse population (Americans). If IQ is genetically determined and a stable feature of behavior, then there has been more evolution of these genes over less than 100 years of time in the US than we see across any two groups of modern humans. That is impossible. Again, IQ does not behave nicely as a genetic trait.

The discovery of a gene or set of genes that would underly IQ has not happened. In some recent studies, IQ is assumed to be very complex and the result of many different genes, and there is some statistical evidence for this. But, there is a big problem there too. Any trait can be linked to a set of genetic variants if the set of genes is large enough. That is a statistical effect and it is not really a link. More like a party trick, or a con game. (In fact this method is a con you may have heard of. I send 10,000 people an email predicting that a certain stock will go up, another 10,000 people an email predicting it will go down. One or the other happens. I then send 5,000 of the people who got the “correct” prediction another prediction, and 5,000 of them the opposite prediction. Now, 2,500 people have gotten two correct predictions from me. I keep doing that until I’ve got several dozen people convinced I am a stock market genius, and I take their money.)

Generally speaking, many behavioral traits have been explained, in part and sometimes in large part, by factors that are not genetic, while at the same time, the hunt for the presumed underlying genes have come up empty. There was great optimism up through the 1990s that genetic underpinning of human behavior … genetic variation corresponding to behavioral variation … would be found. But even as early as 1993 this was being questioned. Here is a sidebar, reproduced in full, from a Scientific American article by John Horgan summarizing the work up to that time:

Behavioral Genetics: A lack of progress report (1993)

CRIME: Family, twin and adoption studies have suggested a heritability of 0 to more than 50 percent for predisposition to crime. … In the 1960s researchers reported an association between an extra Y chromosome and vio-lent crime in males. Follow-up studies found that association to be spurious. MANIC DEPRESSION: Twin and family studies indicate heritability of 60 to 80 percent for susceptibility to manic depression. In 1987 two groups reported locating different genes linked to manic depression, one in Amish families and the other in Israeli families. Both reports have been retracted. SCHIZOPHRENIA: Twin studies show heritability of 40 to 90 percent. In 1988 a group reported finding a gene linked to schizophrenia in British and Icelandic families. Other studies documented no linkage, and the initial claim has now been retracted. ALCOHOLISM: Twin and adoption studies suggest heritability ranging from 0 to 60 percent. In 1990 a group claimed to link a gene—one that produces a receptor for the neurotransmitter dopamine—with alcoholism. A recent re-view of the evidence concluded it does not support a link. INTELLIGENCE: Twin and adoption studies show a heritability of performance on intelligence tests of 20 to 80 percent. One group recently unveiled preliminary evidence for genetic markers for high intelligence (an IQ of 130 or higher). The study is unpublished. HOMOSEXUALITY: In 1991 a researcher cited anatomic differences be-tween the brains of heterosexual and homosexual males. Two recent twinstudies have found a heritability of roughly 50 percent for predisposition to male or female homosexuality. These reports have been disputed. Another group claims to have preliminary evidence fo genes linked to male homosexualty. The data have not been published.

This is from a study by Jay Joseph on the “Classical Twin Method in the Social and Behavioral Sciences”

The classical twin method assesses differences in behavioral trait resemblance between reared-together monozygotic and same-sex dizygotic twin pairs. Twin method proponents argue that the greater behavioral trait resemblance of the former supports an important role for genetic factors in causing the trait. Many critics, on the other hand, argue that non-genetic factors plausibly explain these results…. In 2012, a team of researchers in political science using behavioral genetic methods performed a study based on twin data in an attempt to test the critics’ position, and concluded in favor of the validity of the twin method and its underlying monozygotic–dizygotic “equal environment assumption.” The author argues that this conclusion is not supported, because the investigators (1) framed their study in a way that guaranteed validation of the twin method, (2) put forward untenable redefinitions of the equal environment assumption, (3) used inadequate methods to assess twin environmental similarity and political ideology, (4) reached several conclusions that argue against the twin method’s validity, (5) overlooked previous evidence showing that monozygotic twin pairs experience strong levels of identify confusion and attachment, (6) mistakenly counted environmental effects on twins’ behavioral resemblance as genetic effects, and (7) conflated the potential yet differing roles of biological and genetic influences on twin resemblance. The author concludes that the study failed to support the equal environment assumption, and that genetic interpretations of twin method data in political science and the behavioral science fields should be rejected outright.

With respect to psychiatric disorders, from the same author:

The psychiatric genetics field is currently undergoing a crisis due to the decades-long failure to uncover the genes believed to cause the major psychiatric disorders. Since 2009, leading researchers have explained these negative results on the basis of the ‘‘missing heritability’’ argument, which holds that more effective research methods must be developed to uncover presumed missing genes. According to the author, problems with the missing heritability argument include genetic determinist beliefs, a reliance on twin research, the use of heritability estimates, and the failure to seriously consider the possibility that presumed genes do not exist. The author concludes that decades of negative results support a finding that genes for the major psychiatric disorders do not appear to exist, and that research attention should be directed away from attempts to uncover ‘‘missing heritability’’ and toward environmental factors and a reassessment of previous genetic interpretations of psychiatric family, twin, and adoption studies.

And from researcher Tim Crow:

A substantial body of research literature, identified by nine out of ten papers on genetics in the recent ISI research front on schizophrenia, claims to have established associations between aspects of the disease and sequence variation in specific candidate genes. These candidatures have proven unreplicated in large sibling pair linkage surveys and a targeted association study. Even if the case for an association be regarded as a lucky guess (assuming one gene in 30 000 was guessed right) the large linkage and association studies provide no evidence of sequence variation relating to psychosis at any of these gene loci. Thus this body of work must be regarded as an indicator of the extent to which the ‘eye of faith’ is able to discern meaning in complex data when none is present.

I could go on. There have been further criticisms of the twin studies, for example. The most interesting, potentially, of these studies was on twins reared apart, more or less separated at birth. Commonalities among such individuals would be strong evidence for a genetic underpinning, because these individuals were raised in completely different environments so there would be no chance of a learned or cultural component other than a general background effect of having been raised n the same planet, or in the same country. Right? Well, no. Twins separated at birth were mostly twins that were not all that separated. After all, where do researchers actually find twins truly and distantly separated at birth, especially in the days when people seeking birth parents had hardly become a thing yet? Many of these twins, probably the vast majority, were separated only in the sense that they were raised by different members of the same family, or separately by divorced parents. Many were raised in the same neighborhood or often, the same house. My brother and I are not twins, but we were “raised apart” by the criteria of the twin studies because my family was distributed among the rooms of a two family residence, so technically he and I had bedrooms at different addresses.

In sum, it is easier to find sociological, cultural, or environmental explanations for variation in human abilities, intelligence, or personality traits. The seeming inheritance by family of some of these traits may well be a combination of something genetic and something experiential or cultural, but when looking for the actual underlying causes, genetics has repeatedly come up wanting while environmental explanations do a good job of addressing a fairly large part of the variation we see. Models of race based differences are so poorly done, and are often highly politically motivated, that they should never be trusted. That scientific ship sailed a long time ago.

Maybe the blank slate theory isn’t so bad after all. It does not imply that just anything can happen when making a human being out of a sperm and an egg. After all, it is a blank slate and not a blank whatever. But it is probably not true that some people’s lived experiences are written on slate, while others on white boards, and still others on smart boards, even if there are some people who I’m sure assume that they were.


Selected references:

Horgan, John. 1992. Eugenics Revisited. Scientific American. June.

Joseph, J. (2011). The Crumbling Pillars of Behavioral Genetics. GeneWatch, 24 (6),4–7. Web page
Joseph, J. (2012). The “Missing Heritability” of Psychiatric Disorders: Elusive Genes or Non-Existent Genes? Applied Developmental Science, 16(2), 65–83. doi:10.1080/10888691.2012.667343
Joseph, J. (2013). The Use of the Classical Twin Method in the Social and Behavioral Sciences : The Fallacy Continues, 34(1), 1–40.
Lewontin, R. Human Diversity. 2000, Scientific American Library.
Marks, J. (2008) Race: Past, Present, and Future. In: Revisiting Race in a Genomic Age, edited by B. Koenig, S. Lee, and S. Richardson. New Brunswick, NJ: Rutgers University Press, pp. 21–38. PDF
Marks, J. (2008) Race across the physical-cultural divide in American anthropology. In: A New History of Anthropology, edited by H. Kuklick. New York: Blackwell, pp. 242–258. PDF
Tizard, B. (1974). IQ and Race. Nature, 247, (5349), 316.

_____

Other posts of interest:

Also of interest: In Search of Sungudogo: A novel of adventure and mystery, which is also an alternative history of the Skeptics Movement.

Comments

  1. #1 ppnl
    March 8, 2014

    Erm, I’m not sure why you think that if “… blank slatists start to admit that there could be some sort of genetics behind behavior, and determinists start to admit that experience and learning can also play a role…” is a simplifying view. Both blank slatists and determinists seem maximally simplified in opposite directions. Almost by definition the recognition of the influence of both environment and genetics is an admission of the complexity of the situation.

    I also think it is absolutely clear that the vast majority of the differences in intelligence between individuals is environmental.

    But here is the thing. If intelligence (A poorly defined term at best.) is determined by a single gene then we could expect relatively few alleles and mostly people would be born with the same potential intelligence. OTOH if there are a large number of genes that control intelligence in a complex interaction then you could expect a relatively large number of alleles and it would seem that there would be more variation in intelligence.

    Which is more likely? Well that itself is a surprisingly complex question because the definition of a gene is surprisingly complex.

  2. #2 Greg Laden
    March 9, 2014

    ppnl: I know, it’s a bit counterintuitive. An explanation that involved actual interaction between genes and environment would probably be very complex, and ultimately, more complex than a genes only or environment only explanation. But I don’t see that happening for the most part. Rather, people who are not interested in or don’t like much the idea of genetic explanations still extoll the importance of environment but casually, without evidence or serious integration of the process in their thinking, admit that there must be some genetic component, and vice versa. This is not adding complexity or moving towards a better explanation. It is simply giving the other side of the debate a bit of credit without any further understanding of the process.

    One of the most common responses to the question “Is Human Behavior Genetic Or Learned?” is “well, it’s both” but that response is not based on any actual model of or information about how the two interact. It is merely an aphorism, or an assumption, most of the time. That is not a movement towards understanding the underlying complexity, even if it is a way to admit that there might be underlying complexity.

    Also, as we work our way down from surface behaviors to deep underlying causes through various levels, we may not actually encounter more complexity, but rather, more simplicity. The complexity comes, possibly, as an emergent property of underlying causes and interactions that aren’t complex. So, the assumption that as we delve deeper we will find complexity is just an assumption, and requires testing.

  3. #3 JayMan
    March 9, 2014

    While a pile of deceitful and misleading horsebollocks. I could go on with all the things that are nonsense here, but I will concentrate on a few key erroneous claims.

    I’ll start with the disclaimer that I am Black.

    “In the absence of any useful research results, if blank slatists start to admit that there could be some sort of genetics behind behavior, and determinist start to admit that experience and learning can also play a role, then we are converging on an increasingly simplified view of what is really a very complicated process. We should be gaining more complex, nuanced, and better informed views of how behavior arises, not simpler ones.”

    This doesn’t even make any sense. How could recognizing that behavior arises from a complex interplay of genes and environment be converging to “simpler” views?
    In any case, a level of simplification is the goal of science. “The grand aim of all sciences is to cover the greatest number of empirical facts by logical deduction from the smallest number of hypotheses or axioms,” said Albert Einstein.

    “For example, some families seem to be extra smart. Some have suggested that some ‘races’ are smarter than others (at another time we can discuss why there really are no races, but let’s ‘race’ here as a potentially valid sampling strategy, which it can be even if the underlying races are fictions).”

    Actually, you’d be better off to not discuss it, since race is very much a real thing:

    [Links redacted in order to bypass spam filter]

    “All of these factors have been shown to explain differences between groups to a modest to large degree in several studies. In other words, if you want to explain variation in IQ using non-genetic explanations, you can have some real success.”

    Only if you forget that correlation is not causation. Arthur Jensen in fact invented a name for this: the sociologists’ fallacy. All those things are in fact influenced by genes themselves. Trying to attribute variance in some biological trait to them is essentially tying them to genetic variation.

    “The strongest evidence for a genetic underpinning of IQ is probably the large scale racial model solidified years ago by J. Philippe Rushton. He demonstrated that there is a grouping of brain sizes by race, with Asians having the largest brains, Caucasians the second larges, and Blacks the smallest (these race terms are his). He then showed that these brain sizes correlated with IQ difference. The modern psychometric literature assumes a racial difference in IQs, and asserts that this difference is real, but does to by citing sources that then site sources that ultimately cite Rushton. Rushtons all the way down, as it were. “

    A nice sweeping dismissal of the robust differences in both cranial capacity and brain size between the races. Why don’t you ask a forensic anthropologists about this? Oh, but that’s right, according to this, forensic anthropologists shouldn’t even exist! Nevermind.

    “The range of variation across “racial” groups (or other groups) in modern IQ data is very small compared to the change in IQ measured or estimated over decades of time through the 20th century within a single large and diverse population (Americans). If IQ is genetically determined and a stable feature of behavior, then there has been more evolution of these genes over less than 100 years of time in the US than we see across any two groups of modern humans. That is impossible. Again, IQ does not behave nicely as a genetic trait.”

    So has height. So has obesity. And those things are equally heritable. Indeed, it’s unclear how real the Flynn effect even is. This is where that “environmental and genetic interaction” come into play. The expression of the genes can be different if there are broad changes in environment, just as the crop yield – which are under strong genetic influence – can vary according to factors such as soil quality and climate. The same genes may express differently in different environments.

    As for the twin studies bit, twin studies have repeatedly shown to be highly reliable. But beyond this, even if they were flawed as is claimed here, then why do we get the same results from adoption studies? Why do genome-wide complex trait analyses, which directly assess the degree of genetic similarity between siblings or between unrelated individuals find heritabilities in line with twin studies? The failure to identify the specific genes involved in behavioral traits has been a nice straw man for blank slatists to latch on to, but this ignores the fact that multiple, distinct, and highly robust lines of evidence show that all behavioral traits are highly heritable.

    I will say that citing John Horgan is definitely not a good way to proceed.

    Look, the degree of folly here is rather egregious. We can continue to misinform and pretend that evidence hasn’t conclusively shown the incredibly significant impact of heredity, and stymie the science in the process. Or, we could work with the evidence and allow science to proceed.

    The extent of the falsehood of this piece is well covered, starting with the straightforward title of:

    All Human Behavioral Traits are Heritable | JayMan’s Blog

    And, freshly written the obfuscation of this piece notwithstanding, the case for “environment” is far weaker than Horgan and others would like to project:

    Environmental Hereditarianism | JayMan’s Blog

  4. #4 JayMan
    March 9, 2014

    Missing from the previous comment are these (two links at a time, to get past spam filter):

    Genetic evidence for race:

    Human population structure, part n – Gene Expression

    This map

  5. #5 JayMan
    March 9, 2014

    And, the key evidences for all I have said above, neatly compiled in once place:

    HBD Fundamentals | JayMan’s Blog

  6. #6 Greg Laden
    March 9, 2014

    “This doesn’t even make any sense. How could recognizing that behavior arises from a complex interplay of genes and environment be converging to “simpler” views?”

    I explain what I mean by this in a comment above yours.

    “Actually, you’d be better off to not discuss it, since race is very much a real thing:

    [Links redacted in order to bypass spam filter]”

    Not really, no. It is possible to redefine “race” to fit reality, but then that definition of race is entirely different than what the term has meant for a very long time.

    “Only if you forget that correlation is not causation. Arthur Jensen in fact invented a name for this: the sociologists’ fallacy. All those things are in fact influenced by genes themselves. Trying to attribute variance in some biological trait to them is essentially tying them to genetic variation.”

    Not really. I don’t accept arguments that entire fields of study are fundamentally wrong and thus what they say is assumed wrong, so forget that part of your argument. All arguments about causality and variance in something like IQ or other behavioral features have the causation/correlation problem. Stating that correlation is not causation with environmental factors therefore it’s genes is absurd.

    “A nice sweeping dismissal of the robust differences in both cranial capacity and brain size between the races. Why don’t you ask a forensic anthropologists about this? Oh, but that’s right, according to this, forensic anthropologists shouldn’t even exist! Nevermind.”

    I am a biological anthropologist trained in this area and I’ve asked myself about this. The idea that forensics proves this is not valid. It doesn’t. Forensics of this sort only works when the assumed population is nicely compartmentalized. That only occurs here and there in time and space. This is also how the race fallacy keeps going, same basic principle but with visible features instead of, for example, skull measurements.

    “So has height. So has obesity. And those things are equally heritable.” QED

    “As for the twin studies bit, twin studies have repeatedly shown to be highly reliable. ”

    Well, I gave evidence contrary to this and this is only the tip of the iceberg.

    “Look, the degree of folly here is rather egregious. We can continue to misinform and pretend that evidence hasn’t conclusively shown the incredibly significant impact of heredity, and stymie the science in the process. ”

    I wasn’t pretending.

    “Or, we could work with the evidence and allow science to proceed.”

    That the other guy isn’t doing real science is a tired, old, ad hom, ridiculous argument.

    Nice self-citation there at the end, though!

  7. #7 Greg Laden
    March 9, 2014

    The map and similar maps sho a correlation between geographic distance and genetic distance, as expected.

    Please stop spamming my blog with links to your blog. One or two is enough, if people want to explore your site, that’s great, they now know it is there. Citing specific points if fine, of course.

  8. #8 iuhiuh
    March 9, 2014

    you just cited john horgan AND lewontin in the same post. and you posted this on “scienceblogs.” this article sucked and you’re a fucking retard.

  9. #9 ppnl
    March 9, 2014

    ” Also, as we work our way down from surface behaviors to deep underlying causes through various levels, we may not actually encounter more complexity, but rather, more simplicity. ”

    Well yes but surprisingly enough that is true of most complexity. In fact Chaitin once complained that what is called complexity theory should really be called simplicity. But then he deals with real complexity that is really absolutely complex.

    Look at the Mandelbrot set for example. It has been described as the most complex mathematical object ever yet the generating function is very simple. But despite the simplicity of the generating function it would be hard to take the Mandelbrot set alone and then try to analytically find the generating function if we didn’t already have it.

    When we look at intelligence we are metaphorically looking at the Mandelbrot set. When trying to understand the cause of intelligence we are metaphorically trying to find the generating function. It may be simple and yet still be analytically intractable.

    Unless there is just one gene for intelligence I cannot imagine there would not be substantial differences in genetic capacity for intelligence between individuals. Yet at the same time those differences are likely dwarfed by differences caused by environment. Even the response to the environment is itself partly controlled by genetics and so may differ from person to person. And so point by point the Mandelbrot set unfolds.

  10. #10 Greg Laden
    March 9, 2014

    iuhiuh’s comment is informative.

    Of what I’m not so sure.

  11. #11 John Q Public
    Minneapolis
    March 9, 2014

    The author acts as though the conventional wisdom is that races exist, brain sizes vary between races, and IQs vary between races in part (~50%) due to genetics. These are actually heretical views, rejected because it would be nice if it weren’t true, which is why there are so many Rushton and Jensen references: very few high level researchers wade into these areas (note I’m using a pseudonym: I don’t want to be blacklisted either). You can dismiss them as simple racist confabulations, but, as Galileo would say, ‘it really is there.’ Isn’t truth more important, interesting, and fruitful, than ephemeral attempts to scientifically support social justice? The latter always looks silly generations later, a waste of time for truth-seekers (though not, perhaps, budding populists).

    Here are some references related to the latter two hypotheses. If you want to think ‘black’ and ‘white’ are biologically meaningless, you can of course, though PCA analysis of DNA shows a very high correlation with self-reported racial classification of the black/white/asian type.

    McDaniel, Michael A. “Big-brained people are smarter: A meta-analysis of the relationship between in vivo brain volume and intelligence.” Intelligence 33.4 (2005): 337-346.

    Lewis JE, DeGusta D, Meyer MR, Monge JM, Mann AE, et al. (2011) Correction: The Mismeasure of Science: Stephen Jay Gould versus Samuel George Morton on Skulls and Bias. PLoS Biol 9(7): 10.

    Gignac G., Vernon P. A., Wickett J. C. Factors influencing the relationship between brain size and intelligence. In: Nyborg H., editor. The Scientific Study of General Intelligence: Tribute to Arthur R. Jensen. London: Elsevier; 2003. pp. 93–106

    Distributed brain sites for the g-factor of intelligence. Colom R, Jung RE, Haier RJ Neuroimage. 2006 Jul 1; 31(3):1359-65.

    Birth characteristics and risk of low intellectual performance in early adulthood: are the associations confounded by socioeconomic factors in adolescence or familial effects? Bergvall N, Iliadou A, Tuvemo T, Cnattingius S Pediatrics. 2006 Mar; 117(3):714-21.

    Hamilton J. A. The Association Between Brain Size and Maze Ability in the White Rat. University of California at Berkeley; 1935. Ph.D. Dissertation.

    Sex, bowers and brains. Madden J Proc Biol Sci. 2001 Apr 22; 268(1469):833-8.

    Wickett J. C., Vernon P. A., Lee D. H. Relationships between factors of intelligence and brain volume. Personality and Individual Differences. 2000;29:1095–1122.

    Deary I. J. Looking Down on Human Intelligence: From Psychometrics to the Brain. Oxford, UK: Oxford University Press; 2000

    Early life predictors of childhood intelligence: evidence from the Aberdeen children of the 1950s study. Lawlor DA, Batty GD, Morton SM, Deary IJ, Macintyre S, Ronalds G, Leon DA J Epidemiol Community Health. 2005 Aug; 59(8):656-63.

    Analysis of brain weight. I. Adult brain weight in relation to sex, race, and age. Ho KC, Roessmann U, Straumfjord JV, Monroe G Arch Pathol Lab Med. 1980 Dec; 104(12):635-9.

    Review Genetic and environmental influences on human psychological differences. Bouchard TJ Jr, McGue M J Neurobiol. 2003 Jan; 54(1):4-45

  12. #12 G
    March 10, 2014

    Hot topic this is, to be attracting so much nastiness and overt spam.

    I’m one of those who goes by the heuristic “and/both,” more specifically, “genes determine the range, environment determines expression.”

    Intelligence is a function of the brain. A number of genetic influences bear upon the development of brains: structure, neuroanatomy, neurophysiology, neurochemistry, etc., each of these probably being influenced by numerous genes.

    The gene that codes for serotonin reuptake is probably not the same as the one that codes for the development of the adrenal gland: so now we have two separate genes at minimum, responsible for two distinct sets of psychiatric disabilities: clinical depression (and OCD, which is responsive to SSRIs), and anxiety disorder (which is responsive to beta blockers that act on the adrenal system).

    Multiply the above scenario by the number of variables that contribute to the various functions that make up intelligence: problem-solving ability, pattern-seeking ability, verbal and mathematical abilities, creativity, and empathy.

    Depending on neurochemistry, you might end up with a world-changing genius like an Einstein or a Martin Luther King, or you might end up with an equally smart sociopath who destroys a major investment bank from the inside.

    But you take those genius genes and soak the fetus in prenatal alcohol, and you end up with a kid with an IQ of 70 – 80. Or you deliver the baby to a dysfunctional family and end up with a kid who has PTSD. Or the mother is desperately poor and can’t afford a decent diet, and the kid grows up with some other cognitive disability (and then some closet racist conflates the economic effects of racism with genetics, and concludes that members of race Q are less intelligent than members of race R).

    Then you take that genius kid with a good diet and put her/him in a school system where the first order of business is to not get beaten up by rampant bullies who are trying out for their local street gang, and the result is a smart kid whose #1 skill is staying alive in a zoo.

    Or the smart kid gets hooked on video games or more-overt exogenous drugs, and never picks up a book in his/her spare time.

    Or the smart kid aces it in high school but recognizes that carrying half a mortgage’s worth of undischargeable debt into an economy that’s teetering on the edge is not a smart move, so the kid doesn’t go to college. Maybe s/he opts for the military and rises to become a top-flight NCO instead, or maybe not.

    Whatever genetics that kid started with, are only going to set the outer boundaries. Their environment, including their own behavior, is going to determine what they end up with. Meanwhile, genetic determinists will seek out the gene that caused the kid to get hooked on video games, and environmental determinists try new teaching methods on clearly congenital cognitive disabilities.

    And the rest of us look in from the sidelines and wonder why the hell we can’t, as a society, at least have universally guaranteed prenatal and childhood nutrition, and schools where kids can spend their time learning rather than ducking bullets. (Part of the answer to that is, we spend as much on video games as we spend on NASA.)

  13. #13 Eric Falkenstein
    March 10, 2014

    Considering your friend Greg Horgan last year proposed we ban race and IQ research, I guess it’s all good if it argues for a certain narrative. Anyway, you write:

    ‘it is easier to find sociological, cultural, or environmental explanations for variation in human abilities, intelligence, or personality traits.’

    I agree, it is easier, because nothing is so convincing as an assertion consistent with one’s prejudices, especially for conjectures that aren’t as easily tested as dropping balls from the Tower of Pisa.

  14. #14 Greg Laden
    March 10, 2014

    Eric Falkenstein: You provide as evidence that sociocultural or environmental explanation for variation in human behavior is useless because it supports one’s own prejudices. Personally, I found these explanations useful from the perspective of a biological anthropologists who assumed that a lot of the variation in human behavior would be genetic. Anyway, your argument is non existent. Non existent arguments tend to be non interesting as well.

  15. #15 phillydoug
    March 10, 2014

    Greg (at #2):

    “An explanation that involved actual interaction between genes and environment would probably be very complex, and ultimately, more complex than a genes only or environment only explanation. But I don’t see that happening for the most part. ”

    You’re hanging out in the wrong bars.

    Only a few reactionary holdouts amongst psychologists would say ‘either genes or environment’, and no one with any training in research pays any mind to Rushton, or rubes like Murray and Herrnstein (of Bell Curve fame). IQ as a construct is not recognized by psychologists (the folks that invented the construct) as a simple expression of an individual brain to perform cognitive tasks.

    Anyone suggesting that something as arbitrarily defined as a population (like an ethnic grouping) would show, or could establish, differences in heritable intellectual capacity, knows nothing useful about the study of assessing cognitive abilities (nor do they understand how research of human populations is actually designed and constructed, at least when done competently).

    As far as the mechanisms by which our genes and our experiences (environment, nurturing, culture) shape each other, let me introduce the concept of epigenetics:

    http://learn.genetics.utah.edu/content/epigenetics/epi_learns/

    “Epigenetic tags act as a kind of cellular memory. A cell’s epigenetic profile — a collection of tags that tell genes whether to be on or off — is the sum of the signals it has received during its lifetime…

    As cells grow and divide, cellular machinery faithfully copies epigenetic tags along with the DNA. This is especially important during embryonic development, as past experiences inform future choices. A cell must first “know” that it is an eye cell before it can decide whether to become part of the lens or the cornea. The epigenome allows cells to remember their past experiences long after the signals fade away.”

    Some examples:

    http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3335738/

    J Psychiatr Res. Jul 2011; 45(7): 919–926.

    Epigenetic Modification of Hippocampal Bdnf DNA in Adult Rats in an Animal Model of Post-Traumatic Stress Disorder

    http://cmgm.stanford.edu/biochem118/Projects/2012%20Spring/Smati.pdf

    The Epigenetics of PTSD
    Nadia Smati/ Stanford (2012)
    Genomics and Medicine

    http://www.pnas.org/content/early/2013/04/24/1217750110

    Childhood maltreatment is associated with distinct genomic and epigenetic profiles in posttraumatic stress disorder

    Proceedings of the National Academy of Sciences

    (Quick note, with reference to your above review of IQ and genetics– it is well established that childhood exposure to adversity, i.e., neglect, poverty, violence, war, etc., affects performance on cognitive tests and in school, meaning one’s environment and experiences play a large role in academic outcomes, and test results, at least when one looks at groups)

    http://people.umass.edu/~braunlab/Gluckman%20Nature%20Endo%202009.pdf

    Epigenetic mechanisms that underpin
    metabolic and cardiovascular diseases

    Gluckman, P. D. et al. Nat. Rev. Endocrinol. 5, 401–408 (2009); published online 2 June 2009; doi:10.1038/nrendo.2009.102

    http://www.academia.edu/630370/Biological_memories_of_past_environments_Epigenetic_pathways_to_health_disparities

    Biological memories of past environments: Epigenetic pathways to health disparities.

    Epigenetics 6:7, 1-6; July 2011

    Zaneta M. Thayer and Christopher W. Kuzawa
    The Center on Social Disparities and Health at the Institute or Policy Research; Northwestern University

    *************************

    Some of the coolest, and also disturbing, research that has come out recently suggests that our experiences, environmental exposures, even habits, will produce effects for a great great great grandchildren, without any alteration in gene structure– it’s solely epigenetic.

    So if I had gone on tour with the Grateful Dead instead of going to grad school, subsisted on ramen instead of cheesesteaks, and read comic books instead of Tolstoy, each of these will have a cumulative, subtle effect on things like health status, academic functioning, and soioeconomic status of my descendants three and four generations down the line (at least).

    If you think admission to Harvard is all about the genetics (what the Rushton’s of the world might call ‘the right breeding’– and skin color), you don’t know squat about the brain, genetics, epigentics, or human development. Other than that it’s sound theory.

  16. #16 Greg Laden
    March 10, 2014

    John Q. Public:

    I think you assertion that there is a blacklist is absurd, and your suggestion that anyone would care to put you on it demonstrates unnecessary hubris.

    Anyway, yes, that is a lit of resources on the topic at hand. Nice bibliography mojo you’ve got there. Much of the material in the papers you cite is in fact the subject of the critiques I provided in this short blog post, so I don’t feel a great need to respond to your references.

    Your main argument seems to be that you know a truth others won’t accept. Also, you are Galileo. The readers of this blog are a bit beyond that sort of argument.

  17. #17 Eric Falkenstein
    March 10, 2014

    Laden: ” You provide as evidence that sociocultural or environmental explanation for variation in human behavior is useless because it supports one’s own prejudices. ”

    No I didn’t. I said it is easier to find evidence consistent with one’s prejudices, especially if those prejudices are popular and the assertion is not really simple to test. Therefore, ‘easiness’ is not a good criteria, especially for the proposition that systematic heredity explains zero in between group mental characteristics. That you reflexively translate this rather simple statement into the statement above implies either bad faith or incompetence.

  18. #18 Greg Laden
    March 10, 2014

    Eric, the point I make is very clear. Apparently I can’t help you to understand it, but I did try.

  19. #19 Eric Falkenstein
    March 10, 2014

    “the point I make is very clear”

    And irrelevant! The point you made doesn’t pertain to anything in my comment (inter alia, the word ‘useless’ is yours and logically unrelated to anything I stated). Apparently, you simply transform comments you disagree into simple untenable assertions that weren’t made–yet vaguely related enough for you to think so–and then comment on their falsity.

    Perhaps your core readers are like-minded enough to think this is a good tactic, Horkheimer’s Critical Theory and all, but you guys aren’t scientists, you’re partisan confabulators.

  20. #20 Greg Laden
    March 10, 2014

    I’m referring to the point I make in my post on which you sort of commented.

    You’ve contributed absolutely nothing to this discussion (except the nice bibliography you supplied above) and you’ve insulted my core readers. You’re done here.

  21. #21 Laurent
    March 11, 2014

    If genetic components of intelligence were to be found between human groups, it’ll still tell us not that much.

    In early 90’s, tomato crosses demonstrated that fruit size could improve with using small fruit species in crossing schemes (a seminal paper giving birth of modern QTL breeding methods: De Vicente & Tanksley, 1993).

    Thus, if IQ difference were to have a between-group basis, then we’d better start interbreed, because there would be good odds that these genetic differences imply old polymorphic variants, and interbreeding would result into some offspring much smarter than their parents.

    But…
    1. I doubt this is what people already convinced that these differences are real are willing to, sadly.
    2. There’s no reason to wait for these differences to be proven to interbreed, you can just have fun anytime and for any other rationale.

  22. […] Post: The brightest and the most insightful people in the country? Is Human Behavior Genetic Or Learned? (don’t forget the genotype by environment covariance…) Berg on the sequester: 1,000 […]

  23. #23 Elijah Armstrong
    March 21, 2014

    Greg,

    1. Rushton’s work is not, in fact, at the “root” of anything, except the life-history theory of race differences (and several brain size figures, which, by the way, are accepted by the environmentalists Nisbett et al., 2012). The IQ estimate of 70 for equatorial Africa was first given by Richard Lynn. The IQ estimate of 85 for African-Americans was first given by Audrey Shuey in 1958 (!). The most convincing evidence, in my opinion, that race differences in IQ are partly genetic comes from a paper which does not cite Rushton at all (Piffer, 2013).

    2) Race, in the old-fashioned sense of a set of discrete, Platonic categories of human beings (black, white, Asian, etc.), is certainly a fictional concept. Races can be more productively viewed as “genetic clusters” (to borrow a term from Cavalli-Sforza) that are somewhat continuous and cladistic. Terms like “black” or “white” represent a convenient shorthand or simplification of human genetic diversity. Does this mean that such terms are illegitimate? No. Terms for color are also arbitrary divisions of a continuum, but this does not mean we cannot scientifically study colors.

    Nisbett, R., et al. (2012). Intelligence: New findings and theoretical developments. http://www.apa.org/pubs/journals/releases/amp-67-2-130.pdf

    Piffer, D. (2013). Factor analysis of population allele frequencies as a simple, novel method of detecting signals of recent polygenic selection: The case of educational attainment and IQ., http://lesacreduprintemps19.files.wordpress.com/2014/01/factor-analysis-of-population-allele-frequencies-as-a-simple-novel-method-of-detecting-signals-of-recent-polygenic-selection-copy.pdf

  24. #24 Greg Laden
    March 23, 2014

    I strongly disagree that Rushton is not at the root of anything. The psychometric literature is full of references back to references back to references back to Rushton. This is point I make in the post, and I’m afraid simply saying it ain’t so doesn’t really make it go away. Indeed, Nisbett’s paper (which is a good review) frequently cites Rushton when going back to standard thinking about brains size, IQ, race,etc.

  25. #25 Elijah Armstrong
    March 23, 2014

    Rushton is a standard reference, but that doesn’t mean he is “at the root” of modern psychometrics. Suppose he faked every single datapoint he ever published (which I don’t think he did). That would mean little, since: a) the data on race and IQ has been corroborated by many other researchers; b) Rushton’s main contributions were not the publication or collection of data, but the development of theoretical structures, such as the r-K theory, the general factor of personality, the g-loadedness of black-white differences, etc., all of which have been confirmed by other researchers’ data as well. I could probably defend a genetic background for race differences in IQ without ever citing Rushton once.

  26. #27 Rock
    June 19, 2014

    Just to help clarify on the brain and environment.

    Like height, changes on average too rapidly for selection apply for average IQ and obviously brain size. Brain size and its structure are far more sensitive than either of those because brain morphology changes depending on things you do pretty much when you do them. It can change simply by playing video games, eating rice instead of bread, meditating and learning languages. You can check these specific things on Google. Just go type it in, type the exact words in.

    Flynn effect in both height/body size and IQ is big, the amount of change is just as big as the gaps, even more so if I remember correctly. The temporary average brain size variation between groups can be completely due to environment. Also its only a moderate, mostly weak correlation to IQ. Cranial size(the thing morton measured) has an even weaker correlation. Plenty of people with small brains with higher IQs than people with big ones.

    Then there is epigenetics like mentioned before. Its been tested and found in animals and humans in relation to behavior. There is no argument here. Just check “behavioral epigenetics”.

    Also environment can effect not just expression of genes but also the integrity of them. As an example go check “life style change effect on telomeres”. If you don’t know what they go check.

    Furthermore unlike other physical things like running fast, jumping high or endurance, your ability to do mental things can drastically change even over night sometimes. Go check acquired savant syndrome. There have been people that have simply fallen on their heads and gained the ability to perform extremely complicate mathematics, memorize vast amounts of details that they were not able to do before. Oh and also artistic ability.

    Bottom line is, height, skin and athletic ability are very different to the brain and things in the brain are vastly more dynamic, sensitive, plastic and changeable.

    Its funny all this twin stuff. They can have high heritability but that does not mean environmental conditions can’t change them completely for every single pair in a massive way. It does not mean environment cant change them and their children even.

    All I see is genetic determinists over exaggerating and excluding evidence to construct their own version of reality then try and impose it onto everyone.

  27. #28 Rock
    June 19, 2014

    Hey Greg delete my old one and let this one show. I made some small errors in my original. Thanks.

    Just to help clarify on the brain and environment.

    Like height, changes on average too rapid for selection apply for average IQ and obviously brain size. Brain size and its structure are far more sensitive than other physical things too, because brain morphology changes depending on things you do pretty much when you do them. It can change simply by playing video games, eating rice instead of bread, meditating and learning languages. You can check these specific things on Google. Just go type it in, type the exact words in.

    Flynn effect in both height/body size and IQ is big, the amount of change is just as big as the gaps, even more so if I remember correctly. The temporary average brain size variation between groups can be completely due to environment. Also its only a moderate, mostly weak correlation to IQ. Cranial size(the thing morton measured) has an even weaker correlation. There are plenty of people with smaller brains with higher IQs than people with bigger ones.

    Then there is epigenetics like mentioned before. Its been tested and found in animals and humans in relation to behavior. There is no argument here. Just check “behavioral epigenetics”.

    Also environment can effect not just expression of genes but also the integrity of them. As an example go check “life style change effect on telomeres”. If you don’t know what they are go check. Type in telomeres in google.

    Furthermore unlike other physical things like running fast, jumping high or endurance, your ability to do mental things can drastically change even over night sometimes. Go check acquired savant syndrome. There have been people that have simply fallen on their heads and gained the ability to perform extremely complicate mathematics, memorize vast amounts of details that they were not able to do before. Oh and also artistic ability.

    Bottom line is, height, skin and athletic ability are very different to the brain and things in the brain are vastly more dynamic, sensitive, plastic and changeable.

    Its funny all this twin stuff. They can have high heritability but that does not mean environmental conditions can’t change them completely for every single pair in a massive way. It does not mean environment cant change them and even their children.

    All I see is genetic determinists over exaggerating and excluding evidence to construct their own version of reality then try and impose it onto everyone.

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