Cosma Shalizi has written a two part dialog that is amazingly well in line with my own thoughts on the subject of the heritability of intelligence: g is a statistical artifact, we have brains that evolved for plasticity, not specificity, and that while many behavioral traits have a heritable component, it’s not anything like what the naive extremists among the cognitive science crowd think. There are no genes that specify what you will name your dog — in fact, most of the genes associated with the brain have very wide patterns of expression and functions that are not neatly tied to behaviors: how does an allele of an adhesion factor map to your performance on a math test? It doesn’t, not directly.
Cosma has a wonderful example of the heritability of accents to illustrate the complications of trying to assign a genetic cause to properties associated with race and class and ethnicity. They may look like they’re genetically determined, but they aren’t. In my own family, I noticed a weird phenomenon: my grandparents came from Minnesota, and my mother was born there but moved to Washington state as a child. My grandparents had that Scandinavian-influenced upper midwest accent (if you’ve seen the movie Fargo, you’ve heard an amplified version of the same—most Minnesotans have only hints of that degree of an accent). My mother doesn’t have it. Oddly, though, I’ve heard bits of it in my sisters’ accents, an attenuated version of the already mild Minnesota sing-song, while my brothers and I don’t have a trace of it. I was tempted to speculate that there was a dominant Scandihoovian allele located on the X chromosome, but I suspect the more likely culprit would be sex differences in the influence of maternal and paternal families on boys and girls. That’s harder to tease apart than something as discrete as a gene, though, and it’s also a fuzzy effect that can be affected by scientific scrutiny.
Unfortunately, Three-Toed Sloth doesn’t have a comments section, so if you want to argue about it all, here’s a convenient battle ground in a Pharyngula thread.
I’ve always had a hard time accepting that genes can determine so many minute aspects of our lives. And I know they’ve done some pretty weird comparisons of separated identical twins, and them going into the same careers, and having the same number of children, etc, etc. But, I wonder just how many of the twin pairs end up like this.
As for me, although those studies can be convincing without knowing how many twin pairs they had, I still feel that a lot of our traits are developmentally based. Personally, I see it more rubber than plastic even.
Argument by incredulity, eh?
I think the same sort of argument could be made for a lot of traits (look at what developmental genes do!). There is a large enough gap between biochemistry and morphology or behaviour that this argument could be made about a lot of traits.
In some ways, this is all by-the-by. However genes affect traits (even ones as amorphously defined as intelligence), there is probably some genetic variation for the trait in humans, so the question is how much of the total variation is heritable. I think that can only be answered empirically.
The example of accents just shows that the problem is complicated in humans, because we learn, damn us. However, that doesn’t stop human geneticists (and what other sorts are there?) from devising cunning strategies, e.g. based on twin studies.
With intelligence, the biggest problem is defining it. All the rest is technical detail, and possibly a lot of long-term funding.
Bob
Not only are brains plastic, they are not even microwave-safe …
With respect to separated twins, recall that they have more in common than just genes; the same womb environment, and often similar cultures and similar socio-economic status.
llewelly – that’s why they compare mono- and di-zygotic twins nowadays. There are a few data sets big enough to do it with.
Bob
Dumb argument.
Of course brains are a little bit plastic. Of course brains are hardwired to an extent.
Liberals tend to lean one way and conservatives the other. The only thing which really matters is the evidence.
Curiously, it’s generally agreed in my family that my voice and manner of speech are very like those of my paternal grandfather- whom I never knew. I suspect it’s due to common literary influences.
Brains are plastic, not hard wired
One need only watch the “god hates the world” video to see conclusive proof that at least some brains are very cheap plastic with very faulty wiring.
Brains are indeed plastic, and accents are very slippery…
My son grew up in Pennsylvania…. among (strangely enough) other.american.kids. His Mom & I have fairly regular Scottish accents (Acchhh no! Ye dinna!…. Aye we dae!) although softened much from world travel. But our son has never been able to pronounce Loch correctly (with the ch gutteral, like the complex k/h in chutzpah…)
We’re so ashamed!
Had another thought (that makes at least two!)
If brains are plastic… are they thermosetting or thermoplastic….
I’d say thremosetting (generally), since almost everyone I’ve ever met gets completely intransigent as soon as they get ‘all het up’!
However, the few exceptions to this rule are those fellow athiests and agnostics, who are truly willing to be passionate about their ‘argument’ but will readily accede when faced with countervailing evidence….
So: Theists = thermosetting; non-theists = thermoplastic!
Both my Grandfathers came to Australia from England in their teens. My parents and I were born in Australia. When I started to speak it was with a strong English accent and the speech pathologist said I’d have to learn and modify my speech to be understood like any new immigrant. Even till early High School I was still asked where in England I came from. It was very wierd and no one could work out why I spoke like a Pom.
Now I have a strong country Aussie accent, which works well in Arizona.
It would be interesting to see a twin study where the twins gestated in different surrogates, but my guess is they would be more alike than randomly selected people.
If genetics played no role you would expect a chimp raised as a human to have the same intelligence as a human. Hell, you’d expect a chipmunk raised as a human to have the same intelligence. Unless you’re claiming that there’s some magical human essence that separates us from all other animals.
Ryan, no one said NO ROLE that would be completely dumb.
The intersting thing about genetics and plasticity is you can continue making some changes in both till you get quite old. But if you get thrown a hardwired baddy that messes up making some important protein, its bad news and all you can do is hope medicine catches up. (You can of course also pary but it wont help).
I have a friend who speaks with speaks with a subtle, yet distinct, Brooklyn accent. She was a military brat, so I assumed that she picked up the accent from one of her parents, but neither her parents or grandparents is from the Northeast (much less New York), and she never lived there, only in San Diego, Charleston SC and the Phillipines.
I asked her where the New Yawk accent came from – it turns out that when she was a small child in Charleston, she had a neighbor from Brooklyn whom she spent a lot of time with. None of her siblings spent much time with this neighbor, so she is the only member of her family to drink “cawfee” instead of coffee.
My husband and his brother (not twins) have very different accents. They were both raised in Regina, SK, as was their mother. Their father was from Turkey. My husband and my mother-in-law don’t have thick accents at all, sometimes you have to listen to notice that my husband is Canadian. His brother has been living in Saskatoon for a long time. Both he and his girlfriend have thick accents and use “eh” a lot, which is something that my husband doesn’t do at all and his mother only does occasionally. Their daughter is probably going to follow suit! ;^)
My husband’s friends all have thick accents but when we were talking to some people at a Fermilab lecture they thought that he sounded almost English. Weird…
In general, the question is less whether there’s a genetic component to intelligence (or a gender-derived component, etc.) than whether that component has an effect significant enough to inform public policy. The extreme edge of this consists of eugenics and genocide, but in between you have things like aptitude tests, multiple-track school systems, etc.
As far as I’m concerned, the evidence is that for policy purposes, the genetic component of intelligence is insignificant compared to nurture, and thus essentially worthless. We can’t derive useful information on how to educate a child by examining the IQ scores of his or her ancestors.
This is kind of similar to the homosexuality nature/nurture argument. Again, I think that’s a split issue, but there’s no functional difference between homosexuality rooted at fertilization, during gestation, or in early life unless you already consider homosexuality to be a bad thing.
Actually PZ, your example of accents is bogus to start with. Its well known how those arise and damn obvious that for someone to even “develop” a particular accent, they must be exposed early in life to the sounds, which they must repeat during the sort of baby talk stage, of those specific characteristics. Its why someone who never heard Chinese can’t ever “learn” to speak it without an accent, their brains just don’t *hear* the sounds properly or know how to translate that into the correct accenting. You can get close, but you are never going to get it right, no matter how hard you try. A better example would be the *number* of languages someone manages to learn, since that shows a level of plasticity, which some people lack. And that may be what the real issue is. How much in total can the brain, with respect to certain key mechanisms and processes, adapt to new data. Some of that can be hampered, like with language, by failure to expose someone to the most basic building blocks of the type of skill you are talking about, like how I will probably *never* be able to pronounce the sort of half-l/half-r sound of the sound that, depending on the person translating it, will write as “r” or “l” when Romanizing a Japanese word. Its not *either*. The names Ryoko and Lyoko are functionally equivalent, since there are not Rs or Ls in the original Japanese language, but rather something that is both/neither.
Point is, its not a question of if you can inherit the minor quirks that define *how* someone does a thing, like accents, or odd math tricks, or if they shave with the opposite of their dominant hand for some reason. The issue is more like, “Assuming everyone learns the *basic* building blocks of math logic, such as 2+2 and 3*9, etc., what percentage have sufficiently plastic mind to go way beyond that and learn something like Calculus, without any serious problems?” That person my be unbelievably plastic with respect to language, but be banging their head against the wall trying to just learn Algebra, never mind something more complex. Its not that one is hardwired to “know” math, like some goofy ancient philosopher mumbling about how we “know everything, so are confused, and have to forget stuff as we grow up, by only using the stuff we think is important.”, its that one may have inherent limits, like how you can’t take a distance runner and make them a sprinter, because they simply don’t have the right muscle types in the right proportions to do that well. Why should the brain have some special dispensation from that limitation?
The idea that its so plastic it “can’t” be limited in such ways is just as insane as some people’s idea that what they call their dog is preprogrammed into it. Neither view makes sense in terms of what we know of just general biology, with respect to every other part of the body. The only way you can ignore that is by pulling a creationist trick and claiming that the brain is some black box that follows different rules, so nothing we know about anything else’s plasticity or innate genetic limits can apply to it. And I don’t think that is what you are trying to claim.
Ah, Cosma Shalizi. When he discuss statistics the expectation value converges on that there must be three of him. Every time he blogs about it he manages to teach something new.
Well, the hypothesis that we have passed any strong selection for intelligence and are idling along on plasticity seems consistent with what we see. That brains probably can be very plastic doesn’t seem to be news, the comparable abilities of birds with large mammals and differently sized dog breeds have been mentioned a lot.
Since the rumor is that the microcephalic explanation for the hobbit is relegated to a minor position, perhaps we can add another notch for the idea of plasticity of brains.
So basically you are saying that their brains becomes vulcanized rubbish?
Ah, Cosma Shalizi. When he discuss statistics the expectation value converges on that there must be three of him. Every time he blogs about it he manages to teach something new.
Well, the hypothesis that we have passed any strong selection for intelligence and are idling along on plasticity seems consistent with what we see. That brains probably can be very plastic doesn’t seem to be news, the comparable abilities of birds with large mammals and differently sized dog breeds have been mentioned a lot.
Since the rumor is that the microcephalic explanation for the hobbit is relegated to a minor position, perhaps we can add another notch for the idea of plasticity of brains.
So basically you are saying that their brains becomes vulcanized rubbish?
My dog is named “Darwin”, although a surprising number of religious types seem to hear it as “Darling”.
Anyone done studies on how nature/nurture affects hearing? I do know hearing seems to be extremely selective since people hear what they want to hear.
I was born and raised in New Jersey and lived in Philadelphia for twenty years before moving to L.A. My accent is a hodgepodge- a few Philly-area characteristics, e.g., I pronounce “gas” more like “gaz” and some things I must have gotten from my mom, who grew up in Chicago and taught school in southern Illinois for several years. For starters, I pronounce “Chicago” like a Chicagoan- “shi-CAW-go”, say “chawklit” “clawsit” and “cawfee” for “chocolate”, “closet” and “coffee” and pronounce “eggs” and “legs” as “aigs” and “laigs” a’ la Li’l Abner, which probably came from my grandmother, who spoke like that and was my primary caregiver during my father’s final illness, right around the time that I was learning to talk.
Tests that check items like the cot-caught merger and whether you pronounce Mary, merry and marry differently usually identify my accent as northern Midwest.
It’s a neat subject. I wonder what a real-life Henry Higgins would make of my speech.
I’m running an extremely limited in scope but fascinating experiment in nature v. nuture, in the persons of my two adopted children who are half-bio-sibs, in a very open adoption. While accent itself may not be strictly speaking inherited, voice quality certainly is: my daughter’s voice has very much the same reedy quality as her birth-mother, which is very different from the voice quality of either her brother or my husband and I.
On the other hand, both my daughter and her birth-father are very Goth. Since she has had very limited contact with him, I don’t think it’s a trait acquired by imitation. It’s led me to some speculation as to whether there might be some inherited aspects to personality, or at least casts of mind.
Rew #6
” brains are a little bit plastic ”
http://doctorandy.blogspot.com/2005/07/living-with-half-brain.html
http://www.metacafe.com/watch/205285/amazing_kid_with_only_half_a_brain/
yeah .. and nuclear blasts are a little bit warm…
“It’s led me to some speculation as to whether there might be some inherited aspects to personality, or at least casts of mind.”
I would take that as a given. One also has to take into account the pre-natal environment (it is sometmes hard to seperate th two) but for sure there are dimensions of personality that at the very least are given a leg-up by genetics. People studying rats breed them for things like agression/submission, someone has bred foxes for tameness, and we have been breeding dogs for years on their ability to please humans.
However, whatever you start with, there is still a huge amound of plasticity and ability for it to change.
I don’t see why it’s all or none. There is good evidence that the brain is both plastic and hardwired, and the two need not be mutually exclusive.
As for g being a statistical artifact…wha? I find it hard to believe that a statistical artifact could predict real-world criteria to such a large degree. Or explain why tests which seem to have nothing in common (say, reaction time and a vocabulary test) correlate with each other. Or any other of hundreds of findings that establish g as a robust, real source of individual differences.
The importance of g is another matter entirely, and it may have no real practical significance. But I’ve never seen an argument for it being merely statistical that stands up to any scrutiny once one is familiar with the research.
You mean, to drink coffee instead of cahfee? :o) (British perspective.)
Ah, then just try harder. Not being used to them, I keep forgetting the tones of Chinese syllables, but as long as I happen to remember the right tone, I get it right. It’s just a question of a) understanding that the tones exist and are not some ornamental sing-song — something you’re not likely to guess on your own — and b) practice.
What kind of Japanese? I mean, Japanese has a number of dialects, and I’ve read really weird descriptions of that sound, but the Zompist says “they’re lying”, and what little Japanese I’ve heard (5 people from the same university) agrees: it’s an ordinary non-English, non-French r. The English r sounds more like l than the Japanese one does.
You mean, to drink coffee instead of cahfee? :o) (British perspective.)
Ah, then just try harder. Not being used to them, I keep forgetting the tones of Chinese syllables, but as long as I happen to remember the right tone, I get it right. It’s just a question of a) understanding that the tones exist and are not some ornamental sing-song — something you’re not likely to guess on your own — and b) practice.
What kind of Japanese? I mean, Japanese has a number of dialects, and I’ve read really weird descriptions of that sound, but the Zompist says “they’re lying”, and what little Japanese I’ve heard (5 people from the same university) agrees: it’s an ordinary non-English, non-French r. The English r sounds more like l than the Japanese one does.
My sister picked up my mother’s strong New Jersey accent, but the rest of my siblings and I didn’t (it did not help matters with my sister any that she was married for nine years to a dese-dem-dose blue-collar guy from Queens).
I do have somewhat of a New Jersey/northeast accent, according to those cot-caught tests. So little, though, that people here in NYC think I’m from the midwest, and people in the midwest thought I was from the northwest.
the naive extremists among the cognitive science crowd
Are you sure you mean cognitive, as opposed to personality, psychologists? Cognitive psych generally takes the position that all brains are equal and interchangable, and looks for general abilities across all humans rather than individual differences. I think it’s the personality psychologists you want to pick on. After all, they are the one who came up with I.Q. and E.Q. tests.
The L/R issue was the most obvious one I could think of at the time. And I *do* encounter the problem in some cases where English versions of songs crop up, specifically ones translated to English “by” Japanese companies, rather than by an English singer, where its obvious that some sounds are just not what you expect. This could be due to dialect differences, it could also be that, since contact has become so common and they are often borrowing our words more than we do their’s, that the sound has shifted more towards the English versions. It may be a case similar to the , “Do you speak American English, or the Queens English?”, distinction you get with how some things get pronounced in English. But yes, there is a “real” difference, and the farther back you go when looking at anime, TV, movies, etc, the more likely you are to see L and R blurred and the distinctions between names that use one over the other get foggier.
With respect to the issue of “g,” the best argument I’ve yet seen in dealing with that idea comes from “The Mismeasure of Man” by Stephen Jay Gould. Excellent book, complete with a re-examination of the early statistics leading to that idea, as well the mathematical models supporting it and the logic that underly it.
Here’s my take on the nature/nurture issue in the context of monogamy vs. polygamy.
The whole dichotomy of “nature versus nurture” or “plastic versus hardwired” is ignorant and silly. Nurture grows on top of nature. For example, every child is born with some innate language capabilities, but the particular language the child ends up speaking comes from its nurturing. Every human has strong wiring for the intricate task of throwing a projectile accurately, but with training, some humans can become even better at it. Human males have an inherent proclivity to promiscuity, but socialization places limits on the expression of that proclivity.
The either-or approach to the roles of genetic predisposition versus socialization is stupid. The both-and approach is much better, and the base-elaboration approach is the best simplification of a very complex reality.
I’m not an expert on this, but from what I’ve read, I was under the impression that Gould’s book was outdated as soon as it was published, and didn’t really make any scientifically valid points.
Opposition to g and the heredity of intelligence (which are two completely different things, by the way) seems more motivated by political correctness than by a search for truth, in my experience.
I’m fascinated that people are still a) debating nature v. nurture as though they’re pitted against one another and it’s an actual dichotomy and b) lacking recognition of how incredibly plastic the brain is. My dissertation chair keeps telling me I’m arguing against something that’s long since been decided (that neural plasticity is the standard starting point in neuroscience now) but I keep having to insist that while it’s obviously the *correct* starting point, it still isn’t the *standard* starting point.
Anyone still arguing that genes are hardcore determiners of behavior is only reading research from the 1970s. And that’s research that moves *quickly* with new technologies.
Cosma Shalizi always does a great job.
My brain must be thermoplastic, then, because I’m quite sure I was created by an injection-molding process.
P.Z. is obviously hard-wired to believe in plasticity.
It’s true that Turing machines are infinitely plastic. Given enough memory, each computer can emulate any other computer, though not at the seem speed.
I’m not sure brains behave like this. We don’t expect a blind person to start co-opting her eyes for hearing. Likewise, it’s hard to imagine that brain areas which have been evolved over millions of years for processing visual signals could be co-opted into processing audio signals.
I’m sure the brain is plastic to an extent. I doubt it’s infinitely plastic. I don’t think I could turn into Albert Einstein if only I ran the right software.
I would expect an educator such as PZ to err on the plasticity side of the debate (all other things equal). However, be careful what you wish for. If our brains are that plastic, then what’s to stop religion and governments from manipulating us against our ‘free-will’?
Hmmm, it’s hard to talk about these things without falling into mind-body dualism.
Robin, I haven’t read anybody who argues that genes are hardcore determiners of behavior. My assessment of the community opinion is that plasticity is universally accepted, and that the controversy arises between those who maintain that plasticity can completely override hard-wiring, and those who maintain that hard-wiring always exerts some influence.
As you say, it truly is a tired argument.
In principle, but it would take a real rewrite between expressions at times, since expressive power is wildely different. Assembler, Java and C are each Turing complete, but it would take some work to make one emulate the other. The trick with biology is that it is a rather continous plasticity.
For example, my mother was prohibited from writing with her dominant left hand. (Old school teaching.) The result, or so we surmise, is that she became ambidextrous in most tasks instead of switching dominant side. She didn’t “emulate”, she compromised.
And since she doesn’t know beforehand :-) what arm she will use at a given task she can’t really distinguish between the concepts of left and right. It can be very confusing for others when she gives directions, pointing right and claiming it is left.
In principle, but it would take a real rewrite between expressions at times, since expressive power is wildely different. Assembler, Java and C are each Turing complete, but it would take some work to make one emulate the other. The trick with biology is that it is a rather continous plasticity.
For example, my mother was prohibited from writing with her dominant left hand. (Old school teaching.) The result, or so we surmise, is that she became ambidextrous in most tasks instead of switching dominant side. She didn’t “emulate”, she compromised.
And since she doesn’t know beforehand :-) what arm she will use at a given task she can’t really distinguish between the concepts of left and right. It can be very confusing for others when she gives directions, pointing right and claiming it is left.
Is your mom related to Joe Liebermann?
Years ago in the greater New Haven area where I grew up there were three boys growing up a few doors down. The oldest two were fairly close in age to me and ‘sounded’ the like me. The youngest was about 12 years junior to them. His mom was now working and her mother had moved in. She was from the south. Needless to say, that young boy ended up with a southern accent, startling in our parts. I guess this is an arguement for nurture….
What does g have to do with brain plasticity?
I sense another strawman argument from PZ.
I think people have differing abilities/leanings to pick up on accents as well. When I was at summer camps I invariably started adopting the accents of people I hung out with, whether east coast, southern, the occasional Brit. It was annoying to everyone including me, and I was petrified that they’d think I was making fun of them, but I couldn’t help it. I was like a sponge with no filter. (oo, there’s a twisted analogy.) I spent two months in Edomonton in college and it wasn’t past a week before I was saying “Eh” all the time.
Eugenicists used g to try and prove that because intelligence was a fixed and unchangable value, those who had a low intelligence should be used as quasi-slave labor instead of educated. The fact that education raises intelligence shows brain plasticity and disproves the eugenicists.
Education doesn’t raise intelligence, and it doesn’t increase g.
Quite a good book on this for the total layman is
Matt Ridley’s Nature Via Nurture
To quote Dawkins on the back of the book: – “I would never have expected a book about ‘nature or nurture’ to be even miidly interesting let alone a real page-turner.”
Oli
“Education doesn’t raise intelligence, and it doesn’t increase g”
And we conclude from that what? I assume from the narrow phrasing that the conclusion we’re supposed to hear is “then it must be inherent/genetic?”
If by “education” you mean the effects of a halfwit grade school teacher in a US public school, you’re probably right. However, a child’s environment has a significant influence on g, as well as every other measure of cognitive ability. This includes diet, socialization, activity levels, etc.
Of course intelligence is biological, but the biology of the brain is intensely dependent on its environment, and nowhere near fixed in any sense well into childhood.
Becca #21
With physical traits, it is easy to distinguish between the influences of heredity and environment. If the baby looks like the father, it is heredity. If the baby looks like the neighbor, it is the environment.
I love this quote by Dawkins: “We have the power to defy the selfish genes of our birth and, if necessary, the selfish memes of our indoctrination. We can even discuss ways of deliberately cultivating and nurturing pure, disinterested altruism-something that has no place in nature, something that has never existed before in the whole history of the world. We are built as gene machine and cultured as meme machines, but we have the power to turn against our creators. We, alone on earth, can rebel against the tyranny of the selfish replicators”
At this point in time, LIFELONG neuroplasticity is beyond doubt. The question is: how do we put it to good use?
Some reflections building on Dawkins’ quotes and the Nobel Prize meme at
http://www.sharpbrains.com/blog/2007/06/17/richard-dawkins-and-alfred-nobel-beyond-nature-and-nurture/
Djur : We can’t derive useful information on how to educate a child by examining the IQ scores of his or her ancestors.
Sure, political agenda trumps evidence and logic any time…
Get some real information from people in the trade : Gene Expression.
Has anyone seen this piece in the New Yorker about a linguist who says that a South American tribe’s use of language disproves Noam Chomsky’s universal grammar theory?
That would seem to favor PZ’s plastic-brain hypothesis.
Inadequate nutrition and environmental stimuli have a harmful effect, but once a rudimentary level of necessities has been met, there’s no benefit from further increases.
Caledonian: Your incorrectness on this point may be apparent only to those of us who have made an effort to learn about things in this field, but I think I speak for everyone who reads the comments here when I call you an oblivious, strident asshole.
Your first point is wrong. Deficiencies of either resources or stimulation can impair cognitive capacity, but excess doesn’t lead to further improvement. Very young brains can rewrite themselves to cope with damage very effectively, but there’s simply no evidence that instruction can increase cognitive potential.
As for the second point: Thank you. It means I’m doing something right.
Caledonian: why don’t you do further right and tell us what you think, exactly. You seem to hold that a) IQ tests do measure general intelligence; b) intelligence is innate, only extreme deprivation of some sort can prevent someone from reaching his natural potentiall; and then c) “Education doesn’t raise intelligence, and it doesn’t increase g”
So how do you explain significant IQ changes over time in genetically stable populations, like the Flynn effect?
As usual, Cosma Shalizi’s article is very instructive and astute. Though these arguments were always in the back of my mind, I had not put in the effort to pull them together.
Caledonian
If you continue in this vein, you’ll need to change your handle to curmugeon.
Are you, perchance, feeling a little tetchy this month?
Vishvas Vasuki : As usual, Cosma Shalizi’s article is very instructive and astute..
Yes, as well as HUGELY BIASED by left-wing prejudices.
What’s the conclusion to be drawn?
Even utterly brilliant minds can be assholes…
The import of Cosma’s dialogue seems to be, “Accents are not inherited, therefore intelligence need not be”.
And what is his case against Spearman’s g factor, I wonder?
The accent argument is the one of the most blatant straw man arguments I’ve ever seen, and I’m surprised PZ Myers or three-toed sloth even bothered with it. Sure it’s correlated with achievement and class, but g is strikingly different as it’s provably correlated with genetic variance via twin studies.
And of course the brain is plastic — no one ever disputes that, but it can be both plastic and hardwired at the same time. In the same way that a child can be given the genes for 6ft tall, heart disease, Alzheimer’s, etc. and grow up to be 5ft 10in, with no incidence heart disease, no sign of Alzheimer’s.
g is meaningful. There are disputes over what it really means but it is not just a meaningless statistical artifact. That said TTS is correct that factors other than g probably have a stronger effect on future success. Motivation, curiosity, self determination and the self discipline are good examples and they too may be partially determined by genetics through innate personality factors.
Caledonian is not wrong on his characterization of the influence of nutrition on g. He is not correct in his assessment of the influence of education on g. A nifty recent study on the Flynn Effect:
GENERATIONAL CHANGES ON THE DRAW-A-MAN TEST: A COMPARISON OF BRAZILIAN URBAN AND RURAL CHILDREN TESTED IN 1930, 2002 AND 2004
ROBERTO COLOM a1 , CARMEN E. FLORES-MENDOZA a2 and FRANCISCO J. ABAD a1
Abstract
Although gains in generational intelligence test scores have been widely demonstrated around the world, researchers still do not know what has caused them. The cognitive stimulation and nutritional hypotheses summarize the several diverse potential causes that have been considered. This article analyses data for a sample of 499 children tested in 1930 and one equivalent sample of 710 children tested 72 years later, the largest gap ever considered. Both samples comprised children aged between 7 and 11 who were assessed by the Draw-a-Man test in the city of Belo Horizonte, Brazil. Further, one additional sample of 132 children was assessed in 2004 in a rural area very similar in several diverse factors to the 1930 urban sample. The results are consistent with both the cognitive stimulation and the nutritional hypotheses.