Editing has happened to this comment since the first reply was posted to it. At first I just shared some links to scholarly articles on genetic influences on human intelligence, as I was about to go out the door to have a walk with my son the hacker as this article reached HN's front page. Now I'm back at my computer to provide some more commentary on helpful background reading for the newspaper article from today (which I learned about from a researcher on this issue). Over the years here on HN, I have often seen mistaken conclusions about "heritability" and its relationship to human intelligence from HN participants who haven't kept up with the current research literature. I keep up with the current research literature on human behavioral genetics by weekly visits during the school year to the Readings in Behavioral Genetics and Individual Differences Psychology "journal club" (graduate seminar) at the University of Minnesota.
has log-in authentication to facilitate sharing current journal articles among seminar participants. The seminar also has an email list from which I learned about the New York Times article submitted here, just after today's seminar.)
An old-fashioned view of heritability estimates for human intelligence, which I see repeated frequently on HN, is that heritability constrains controllability ("malleability") of human behavioral traits. Nothing could be further from the truth.
Johnson, Wendy; Turkheimer, Eric; Gottesman, Irving I.; Bouchard Jr., Thomas (2009). Beyond Heritability: Twin Studies in Behavioral Research. Current Directions in Psychological Science, 18, 4, 217-220
is an interesting paper by some of the researchers most familiar with research on human twins, including the director of the Minnesota Study of Identical Twins Reared Apart, which includes the statement "Moreover, even highly heritable traits can be strongly manipulated by the environment, so heritability has little if anything to do with controllability. For example, height is on the order of 90% heritable, yet North and South Koreans, who come from the same genetic background, presently differ in average height by a full 6 inches (Pak, 2004; Schwekendiek, 2008)."
Another interesting paper,
Turkheimer, E. (2008, Spring). A better way to use twins for developmental research. LIFE Newsletter, 2, 1-5
admits the disappointment of behavioral genetics researchers. Eric Turkheimer, a leading scholar in the Behavior Genetics Association, points out that the interpretation often given to "heritability" findings that they somehow measure genetic constraint on variation in a human trait is wrong.
"But back to the question: What does heritability mean? Almost everyone who has ever thought about heritability has reached a commonsense intuition about it: One way or another, heritability has to be some kind of index of how genetic a trait is. That intuition explains why so many thousands of heritability coefficients have been calculated over the years. Once the twin registries have been assembled, it’s easy and fun, like having a genoscope you can point at one trait after another to take a reading of how genetic things are. Height? Very genetic. Intelligence? Pretty genetic. Schizophrenia? That looks pretty genetic too. Personality? Yep, that too. And over multiple studies and traits the heritabilities go up and ...
I'm downvoting you because this method of cherry-picking large quotes or abstracts out of citations makes for a lot clutter but you don't actually offer us any synthesis. I would rather read your synthesis and read the abstracts if I want to. I came to HN to converse with you, not Johnson, W. and Chabris, C.F.
Just so the current reply to your comment isn't the only one: I really appreciate that you keep track of this information and make it available to others. I still have the attention span for a few minutes' reading, and I prefer a dense text full of citations over some schmuck's strongly-voiced opinion or an anecdote about that one time they went to that one thing. So, thank you.
I beg your pardon, but unfortunately this is not my field, so I tend to look for the abstract/intro/conclusion and presume the intermediate parts are correct.. :-)
If I gather the gist of your essay correctly, current research demonstrates no strong connection between IQ and particular genetic influences.
Heritability is very hard for a layperson (such as myself) to wrap his head around, because the meaning assumed by the layperson ("how much a trait is determined by genetics rather than by the environment") is superficially correct, and accurately sums up the intuitive idea that various technical definitions of heritability are based on, but scientific estimates of heritability usually differ from the intuitive definition in significant ways. For example, one common definition of heritability, the one given by Wikipedia as a matter of fact, has a very important twist: "The heritability of a trait within a population is the proportion of observable differences in a trait between individuals within a population that is due to genetic differences." In this definition, heritability explicitly depends on the choice of population. For example, if North and South Korea are considered as a single population, you will get a different result than if they are considered separately. It's easy to misuse population-specific measures of heritability to make inappropriate cross-population comparisons. For example, if intelligence is highly heritable among native-born Dutch and highly heritable among native-born Croats, it might seem reasonable to conclude that IQ differences between Dutch and Croats must be genetic. Yet the same argument would show that the difference in height between North Korea (where height is presumably highly heritable within the population) and South Korea (ditto) must be genetic.
Heritability of something that so strongly is "nature versus nurture" is very hard to pin down. For instance consider a genetic trait that makes kids uglier. (In honor of this article, I'll state the negative version.) Those kids, being less engaging, will get less interaction. It is known that decreased interaction is correlated with stupidity. Therefore all else being equal, that gene will make you stupider. In twin studies that gene will definitely contribute to the heritability of IQ.
However stop and think about it. The fact that this iota of stupidity is heritable is a testament to the impact of environment on IQ, and the fact that the environment that you experience is correlated with who you are.
Because it is the universal standard, from when the internet protocols involved mail carriers and the packets involved sheets of paper. It is the universal standard because it interrupts the flow of thought as little as possible. If I decide I want read their articles, I will.
During commencement at our medical school, one of the second-years on stage said "I know what you're all thinking: you were expecting all sorts of crazy intellectuals and artists. But everyone is so . . . normal."
'Real' crazy intellectuals and artists don't study medicine, they study the Humanities or don't study at all. The rigor and discipline required of medical students and doctors would actually favour those being 'normal'; I wouldn't, personally, have expected anything else.
In the simplest case, imagine that there are genes that determine quality x, and others that determine quality y, and intelligence depends on how close x/y is to some constant c.
If intelligence were determined by genes in that way, you wouldn't find it by looking for ("smart") genes whose presence was correlated with intelligence, or ("stupid") genes whose absence was.
I used beauty as an example because it seems unlikely that there is a single "beauty" gene whose presence makes human faces beautiful, but rather that beauty is a product of the interaction of multiple genes that control the dimensions of the face.
I would like to elaborate on that idea by saying that there is a feedback loop between the persons environment and his innate tendencies . I'm specifically referring to the feeling of satisfaction you get as you become better and better at something . It is that feeling of satisfaction and the inner drive that would provide the impetus needed to continue working harder and harder to master the discipline . However if all the components aren't in "proportion" , this feedback loop between practice -> improvement -> satisfaction -> urge to practice more gets broken .
I think PG is mainly talking about how the ratio of certain personality elements and basic strengths might contribute to a higher perceived "intelligence".
i.e. Someone with a high EQ (Emotional Quotient) relative to their spatial reasoning might seem more intelligent than the person with lower EQ and higher spatial reasoning, while someone with an equally high EQ and spatial reasoning might develop some sort of personality disorder. (Hopefully not, but just an example)
This could probably be extrapolated into ratios between language skills, creativity, ability to grasp abstraction, memory, etc. etc.
Serendipity - just the other day I was replying to a comment about education and IQ and explained I didn't believed in ethnic differences of IQ, but also in IQ altogether - http://news.ycombinator.com/item?id=4680279
At least looking for "dumb genes" is more plausible, because if IQ is an aggregate of multiple functions, some functions could be separately damaged
Copy paste:
The current perspective of IQ and ethnicities show that while there might be slight differences, they are dwarfed by the differences in the education process.
Regarding IQ:
First, I don't believe that IQ exist as a measurable quantity - IQ is too many things thrown together in a single bad. Tests group together various things which may be handled by different subsystems in the brain. If there is something called IQ, it's an aggregate.
Anyway, if there was such a unique quantity, actual data shows a progression of IQ scores in time - therefore if the tests are considered accurate and unbiased, it must be a "quantity" that can evolve based on the society a person lives it. It should then be considered not as a value, but as a function depending on a variable called society.
I do not know if studies have tried to measure the accuracy of repetitive measurement in low education adults enrolled in a learning program. If there are such studies and if they show inconsistent result (ie any change of IQ), then IQ should be considered as a function of 2 variables : f(society, personal experience).
Now, even if we consider that at a time t it could be accurately measured and that societal bias could be removed, considering how other qualities (such as determination, work ethic, consistency, creativity, competitiveness...) influence the outcome of any human activity, it seems foolish to rank people based on just one quality - especially if we don't know the other values, and their individual ponderation in the end result.
This ponderation could also be different depending on the activity, and IQ provide an absolute advantage in some activities (rhetoric?), but say determination would give an absolute advantage in other activities (startups?).
>Anyway, if there was such a unique quantity, actual data shows a progression of IQ scores in time - therefore if the tests are considered accurate and unbiased, it must be a "quantity" that can evolve based on the society a person lives it. It should then be considered not as a value, but as a function depending on a variable called society.
Seriously? Couldn't it just be the subjects getting used to the tests? That's not the point though. It doesn't mean subjects are getting smarter. It just means they are learning, which is natural. However if we have two subjects and subject A gets 115 IQ points the first time while subject B gets 104, 111, 113, 115 IQ points after four consecutive test respectively, it's clear that subject A is superior intellectually in that they can achieve more in less time.
Maybe a full society is getting used to the tests, or maybe the tests are biased.
Even with you example (considering repetitive test at the same time on 2 person from the same society), it could show many things: a) that the measurement is flawed b) that you should retest A to see if he also get better scores c) failing that, A has a fixed IQ score while B can improve d) if A improves too what's the limit?
Finally, "it's clear that subject A is superior intellectually " - even if B would get say 120 on its final test while A ends with 118??
Why is the idea of innate IQ still taken seriously if there's so little evidence for it? If intelligence is just the ability to think in a structured abstract way, doesn't it make sense to think of it as a skill developed over time? I mean, it's not hard to think of spending most of your time in a different mode of thought. I'd say that for most people their normal day to day tends to require concrete or social/emotional information processing.
If it seems that intelligence (specifically abstract structured thought) seems to stabilize early in life, maybe it's something that starts developing even earlier. A strategy for prioritizing, filtering, and processing information from a world of endless stimuli (of which abstract/structured would be only one such strategy) would start developing the moment we're born. By the time you're 10, you'd already have 10 years of "practice".
First and foremost you don't need evidence to look for evidence. A hypothesis is enough.
Secondly, there is evidence that IQ is at least in part genetic. There is no other way to explain geniuses, child prodigies, and mentally retarded individuals whose environments vary greatly.
Sure there is: chemical exposure balance or random variation in the uterine or infant environment.
Fetal alcohol syndrome reliably retards kids, and it isn't genetically inherited. Hypothetically, maybe something like adderall works in utero with lifelong effects.
Also, hypothesis formation should be motivated by data, or else you are wasting time searching through an exponential space with 0 probability of finding a correct one.
Which seed will grow better depends not just of its genes, but also of environment, weather and of how much it was fertilized.
This, for example, is one of the answers why rich getting richer. The difference in environment + variety of experience matters much more than difference in genes, in cases where there is no inherited disorder.
By changing environment, behavior and altering mental models (unlearning the learned helplessness, for example) it is possible to improve even IQ scores.
This is how the Flynn effect works - it is effect of the environment + variety of experience.
27 comments
[ 3.3 ms ] story [ 28.6 ms ] threadhttp://www.psych.umn.edu/ugrad/pastsyllabi.html
(One or two past syllabuses of the seminar are available above. The current course page
http://www.psych.umn.edu/courses/mcgue/psy8935/
has log-in authentication to facilitate sharing current journal articles among seminar participants. The seminar also has an email list from which I learned about the New York Times article submitted here, just after today's seminar.)
An old-fashioned view of heritability estimates for human intelligence, which I see repeated frequently on HN, is that heritability constrains controllability ("malleability") of human behavioral traits. Nothing could be further from the truth.
Johnson, Wendy; Turkheimer, Eric; Gottesman, Irving I.; Bouchard Jr., Thomas (2009). Beyond Heritability: Twin Studies in Behavioral Research. Current Directions in Psychological Science, 18, 4, 217-220
http://people.virginia.edu/~ent3c/papers2/Articles%20for%20O...
is an interesting paper by some of the researchers most familiar with research on human twins, including the director of the Minnesota Study of Identical Twins Reared Apart, which includes the statement "Moreover, even highly heritable traits can be strongly manipulated by the environment, so heritability has little if anything to do with controllability. For example, height is on the order of 90% heritable, yet North and South Koreans, who come from the same genetic background, presently differ in average height by a full 6 inches (Pak, 2004; Schwekendiek, 2008)."
Another interesting paper,
Turkheimer, E. (2008, Spring). A better way to use twins for developmental research. LIFE Newsletter, 2, 1-5
http://people.virginia.edu/~ent3c/papers2/Articles%20for%20O...
admits the disappointment of behavioral genetics researchers. Eric Turkheimer, a leading scholar in the Behavior Genetics Association, points out that the interpretation often given to "heritability" findings that they somehow measure genetic constraint on variation in a human trait is wrong.
"But back to the question: What does heritability mean? Almost everyone who has ever thought about heritability has reached a commonsense intuition about it: One way or another, heritability has to be some kind of index of how genetic a trait is. That intuition explains why so many thousands of heritability coefficients have been calculated over the years. Once the twin registries have been assembled, it’s easy and fun, like having a genoscope you can point at one trait after another to take a reading of how genetic things are. Height? Very genetic. Intelligence? Pretty genetic. Schizophrenia? That looks pretty genetic too. Personality? Yep, that too. And over multiple studies and traits the heritabilities go up and ...
If I gather the gist of your essay correctly, current research demonstrates no strong connection between IQ and particular genetic influences.
However stop and think about it. The fact that this iota of stupidity is heritable is a testament to the impact of environment on IQ, and the fact that the environment that you experience is correlated with who you are.
--
[1] citation 1
[2] citation 2
[3] citation 3
Could you expand on that a little, please? How would a working scientist test the hypothesis you advance here?
They might operate better if they are of similar proportions.
If intelligence were determined by genes in that way, you wouldn't find it by looking for ("smart") genes whose presence was correlated with intelligence, or ("stupid") genes whose absence was.
I used beauty as an example because it seems unlikely that there is a single "beauty" gene whose presence makes human faces beautiful, but rather that beauty is a product of the interaction of multiple genes that control the dimensions of the face.
i.e. Someone with a high EQ (Emotional Quotient) relative to their spatial reasoning might seem more intelligent than the person with lower EQ and higher spatial reasoning, while someone with an equally high EQ and spatial reasoning might develop some sort of personality disorder. (Hopefully not, but just an example)
This could probably be extrapolated into ratios between language skills, creativity, ability to grasp abstraction, memory, etc. etc.
At least looking for "dumb genes" is more plausible, because if IQ is an aggregate of multiple functions, some functions could be separately damaged
Copy paste:
The current perspective of IQ and ethnicities show that while there might be slight differences, they are dwarfed by the differences in the education process.
Regarding IQ:
First, I don't believe that IQ exist as a measurable quantity - IQ is too many things thrown together in a single bad. Tests group together various things which may be handled by different subsystems in the brain. If there is something called IQ, it's an aggregate.
Anyway, if there was such a unique quantity, actual data shows a progression of IQ scores in time - therefore if the tests are considered accurate and unbiased, it must be a "quantity" that can evolve based on the society a person lives it. It should then be considered not as a value, but as a function depending on a variable called society.
I do not know if studies have tried to measure the accuracy of repetitive measurement in low education adults enrolled in a learning program. If there are such studies and if they show inconsistent result (ie any change of IQ), then IQ should be considered as a function of 2 variables : f(society, personal experience).
Now, even if we consider that at a time t it could be accurately measured and that societal bias could be removed, considering how other qualities (such as determination, work ethic, consistency, creativity, competitiveness...) influence the outcome of any human activity, it seems foolish to rank people based on just one quality - especially if we don't know the other values, and their individual ponderation in the end result.
This ponderation could also be different depending on the activity, and IQ provide an absolute advantage in some activities (rhetoric?), but say determination would give an absolute advantage in other activities (startups?).
Seriously? Couldn't it just be the subjects getting used to the tests? That's not the point though. It doesn't mean subjects are getting smarter. It just means they are learning, which is natural. However if we have two subjects and subject A gets 115 IQ points the first time while subject B gets 104, 111, 113, 115 IQ points after four consecutive test respectively, it's clear that subject A is superior intellectually in that they can achieve more in less time.
Maybe a full society is getting used to the tests, or maybe the tests are biased.
Even with you example (considering repetitive test at the same time on 2 person from the same society), it could show many things: a) that the measurement is flawed b) that you should retest A to see if he also get better scores c) failing that, A has a fixed IQ score while B can improve d) if A improves too what's the limit?
Finally, "it's clear that subject A is superior intellectually " - even if B would get say 120 on its final test while A ends with 118??
If it seems that intelligence (specifically abstract structured thought) seems to stabilize early in life, maybe it's something that starts developing even earlier. A strategy for prioritizing, filtering, and processing information from a world of endless stimuli (of which abstract/structured would be only one such strategy) would start developing the moment we're born. By the time you're 10, you'd already have 10 years of "practice".
First and foremost you don't need evidence to look for evidence. A hypothesis is enough.
Secondly, there is evidence that IQ is at least in part genetic. There is no other way to explain geniuses, child prodigies, and mentally retarded individuals whose environments vary greatly.
Fetal alcohol syndrome reliably retards kids, and it isn't genetically inherited. Hypothetically, maybe something like adderall works in utero with lifelong effects.
Also, hypothesis formation should be motivated by data, or else you are wasting time searching through an exponential space with 0 probability of finding a correct one.
This, for example, is one of the answers why rich getting richer. The difference in environment + variety of experience matters much more than difference in genes, in cases where there is no inherited disorder.
By changing environment, behavior and altering mental models (unlearning the learned helplessness, for example) it is possible to improve even IQ scores.
This is how the Flynn effect works - it is effect of the environment + variety of experience.