The presumption being examined here is that humans are divisible into different groups (races would be one term for those groups) that are genetically distinct from one another in a way that causes those groups to have group level differences in average intelligence, as measured by IQ. More exactly, this post is about the sequence of arguments that are usually made when people try to make this assertion.
The argument usually starts out noting that there are dozens of papers that document group differences in IQ. I'll point out right now that most of those papers are published in journals with editorial boards staffed in part or in total with well known racist scientists such as J. Philippe Rushton. That fact is not too important to what I have to say here, but since the usual argument about race and IQ starts out with "Hey, look at all these papers in these great journals" it is worth noting.
Heritability of IQ measures is then proffered, often in reference to the famous "twin studies" which show a high heritability for IQ. Heritability is a measure derived from covariance between relatedness and some phenotype. Heritability is not genetic inheritance. It is scientifically incorrect and probably academically dishonest to assume or insist that a high heritability value means that something is genetic. It often is, but it need not be. The truth is, that there are many things that could have a high heritability value but that we know are not genetic, so we don't make a heritability estimate. There are other things for which we have strong a priori biological arguments that hey are genetic, and we thus make heritability estimates as part of the research on those things. Then there are things that we don't know the cause of, and in those cases, making an estimate of heritability is useful as an exploratory tool. But, and this is important, arriving at a high value for heritability does not indicate genetic inheritance.
If you apply the methodology of the twin studies to language, you would find that having the capacity of language is of a similar heritability of having one head (as opposed to zero or two heads, for instance): Undefined. The number of heads does not vary, and heritability is a measure of covariation (I use the term "covariation" in a non-technical sense here). If you apply these methodologies to what language someone speaks, the heritability for that trait is very high, much much higher than for IQ. If you apply the same method to heritability of geography (the lat/long of where someone lives), it is even higher, especially for babies or people living in traditional societies.
Does everyone understand why that is the case? Familial or cultural causes may be very strong but not genetic. Using this method, if high heritability means that IQ is genetic, then so is which language you speak and so is what part of the world you live in.
The smoke and mirror part of this is equating heritability with inheritance. We speak the language we speak because it is the language of the culture we grow up in, not because of a gene for speaking French vs. a gene for speaking Sumerian.
This makes sense because we know how a person acquires language, so no one even tries to measure heritability of which language someone speaks. (Same with heritability of geographic location. It would be an absurd measure.) But people make the assumption that intelligence is inherited. Why do they make that assumption? Because lots of people for a long time wanted to, and in some cases, needed to believe this so, and thus it has become part of our culture. It is part of our uncriticized received knowledge, along with other racialized ideas and various sexist ideas, and so on. But recent research (meaning over the last 30 years) has shown us that other than in the case if inherited neuro-developmental diseases, it is impossible to imagine how intelligence can be inherited in such a way as to explain the variability we see in the most inter-group differences. Maybe a little, but not that much. That there is some genetic component is not impossible, but it is very hard to maintain the idea that it is genetic and ethnic, or genetic and racial, or genetic and explanatory of more than a few IQ points in most people. There are no genes, there are no developmental mechanisms, that have been identified. So, to many the issue of inheritance (not heritability, but inheritance via genes) of intelligence is not really an issue.
However, there are many who still need to hang on to this belief. Why they need to hang on is itself an interesting question. I can't say for a given individual but I've been engaged in this conversation for 30 years and in my experience it is very often because of a desire to support a racialized model of human behavior.
The evidence for the usual IQ/Group/Race/Ethnicity/Genetic model we see is always given first as group differences. When the language and geography analogs are brought up, we always see the twin studies brought in. But twins are raised together in the same environment. So they have the same language, the same cultural customs, the same geography etc. That they have the same IQ is not surprising.
There is an interesting set of interactions between familial effects and environmental effects with any of these twin studies results, but it has to be understood that heritability is not inheritance. If you have a genetic mechanism that is real (not inferred or made up) that integrates with a developmental process that can manifest a phenotype based on a genotype (that is real, not made up or inferred) then you can translate heritability to genetic inheritance, roughly. We seem to see this in a number of psychological conditions/diseases, for instance, and obviously we see it for a lot of physical traits. If on the other and you have familial effects that would cause offspring to resemble their parents without genes then cultural/social/familial context is more likely to be the explanation.
Variation in IQ across groups in a single society (like in the US) (which is not the same as a single culture) is known to be primarily caused by SES and home environment, and is indicated by such things as parents' educational level. Educational levels of Americans have been going up for a hundred years. So has IQ. IQ can jump up in a generation if one generation is educated and changes home environment and SES etc., and thereafter those offspring and grand offspring have higher IQ's. No new alleles were introduced to cause those changes. Cultural differences were introduced, and we have a concept of the mechanism by how that works.
The difference in IQ across time within a given population is sometimes much greater than the difference in IQ across the usual groupings of people (i.e., "race"). When scientist seek societal, cultural, nutritional and educational explanations for differences in IQ they find them easily. When scientists who have this need for group differences to be genetic seek those genetic explanations for differences in IQ they have to invent new and shall we say "interesting" statistical techniques to justify how their usually cooked data underlie their biologically implausible explanations. The latest is "there are thousands of genes and there are so many we can't see the pattern,and that is the pattern." Funny that. The number of genes with tiny variants that "must be" the cause of variation in IQ is going up and up and up and the number of genes that are estimated actually exist in the human genome has gone way down. At this point, we are very close to saying that individual variation in IQ is best explained by ... which individual you measured the IQ in!
Let me explain that in another way, which is an analogy though it looks like a statistical argument (don't mistake the two). If I show you two points on a graph, I can describe a line indicating their relationship with the formula Y = mX + b (the formula for a line). I can use the same formula to describe the line representing a scatter of points, but the line might be a poor describer of the scatter. How bad it is may be indicated by a statistic (a correlation value or a "R" value or something). But, if I change the formula to Y = m1X1 + m2X2 + b then I get a curvy line that may match the points better. But it will still be imperfect. But, if I add even more coefficients so there is one coefficient per point, then I go back to a (nearly) perfect describer of the line once again. Because, I've drawn a line (more or less) that starts with the first point, then goes to the second point, then to the third point, etc. etc.
And that would be cheating.
And that would be pretty close to what some of the more recently implemented statistical models of genes and IQ do. If I include every allelic variation in humans (hypothetically) and correlated that to individually measured IQ, I've drawn a line from one human's genetic value (along one axis) and IQ value (along another axis) to the next person, the next person, and then the next person so on down the line. At this point, ladies and gentlemen, we show that IQ correlates (almost) perfectly with fingerprint.
The next argument in favor of the genetic inheritance of intelligence is often to link IQ to head size or brain size. However, much of the data related to this research is very made up or cooked, and the causal arrow is problematic. Also, a third or fourth level factor in IQ is diet, which may affect brain size. Separately, a primary factor in skull shape and bone thickness is also diet (though in totally unrelated ways) which in turn is ethnic/regional... Bottom line, the system is complex, but the data do not support the assertion unless you make a big part of the data up, and Rushton has famously done so.
Another argument that is often made to salvage the genetic determination (by racial group) of intelligence is the between national data that has been more recently assembled and foisted on us. This is no different than ethic groups in the US. IQ is a standard measure, and groups vary in this value. Other measures will also result in variation. The variation is there, and the group level distinction is there. But finding more examples of that does not lead towards the conclusion that this is racial or genetic. Across nations we see a lot of measures that we know change (often in predictable directions) over time with industrialization or various other transitions. National IQ, fertility, various health measures, and so on all do this. And, of all these measures, the most suspect in terms of quality of data is IQ (excepting some more obscure health related data). These IQ comparisons don't tell us much.
The final argument in favor of the inheritance of IQ via genes passed on from parent to offspring is usually to cite the twins separated at birth studies. These studies, however, simply do not show this. These twins are not separated at birth in the way most people think they are. Usually, the twins knew each other as they grew up, and/or knew commonly held family members. They lived in the same culture, usually in the same city, often in the same neighborhood, and sometimes even in the same physical house. They went to the same school and had the same diet. Separated at birth in these studies usually means grandma and grandpa took one of the twins to raise because mom and dad were strapped. Grandma and grandpa may have lived down the street. The kids may have attended the same school, even the same classes, and spent a lot of time together outside of school.
I was separated (though not from birth) from my older brother, because he lived on the second floor of a two family house, and I lived on the first floor. By the exact criteria of the twin studies, we would be counted as separated because it happened early enough in my life. But, that household I grew up in was a single household that happened to be set up in a two family house. The two floors were connected by an internal rear stairway that led to locked doors (had we locks). I was rather shocked to realize at one point as a child that we were the only family in my neighborhood with two kitchens. (Or two bathrooms, for that matter.)
There may be a small component of intelligence that is inherited, but it seems to be swamped by other factors. The insistence that genes determine intelligence and that these genes are divided up in our species by groups that are often defined racially is usually misguided, and is scientifically wrong. The supra-ultimate argument, after the final argument, brought up in this sort of conversation is usually that the anti-racist argument is a Politically Correct argument, yada yada yada. But it is actually a scientific argument, and the racialized intelligence argument is not. Making the latter a politically incorrect argument.
Which is kind of funny.
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Great post! I get so sick of people trying to prove that intelligence is somehow different in different races. The biggest problem I see with this is that there is no real biological definition of "race" among humans, since genetic diversity is greater within "races" than between them. But I also don't understand why IQ is used as a measure of intelligence. This nearly ensures that we find differences between groups; IQ measures some aspect of intelligence, but there is no good, objective, culturally insensitive measure of intelligence.
Personally, I'm in the camp that believes intelligence will eventually be shown to have a genetic basis, but it will be a very complex genetic basis (meaning low heritability), just like personality or similar traits. And, as you point out, the environmental component is likely to be huge, possibly even swamping out the measurable genetic effects.
Typical drivel from a liberal who lacks the courage to accept the mountain of evidence that races differ in IQ.
First, IQ is clearly inherited. Studies of identical twins raised apart show very high IQ correlations. In fact, they show higher IQ correlations than fraternal twins raised in the same household.
That should settle the genetic heritability argument, but there's more: Genes that affect IQ have already been discovered. One example is the CHRM2 gene: http://www.ncbi.nlm.nih.gov/pubmed/17160701
Second, race (or populations or humans) is genetically meaningful because it is based on ancestry (i.e., which continent your ancestors came from). Genetic racial differences are evident in skin color, eye color, hair color, hair texture, height, weight, muscle mass, testosterone levels, brain size, skull size, and just about everything else. It would be implausible that these differences don't extend to intelligence.
Third, racial differences in IQ exist even when all other variables are held constant. Income, for instance, explains only a tiny fraction of the gap. Nothing else makes a dent. (http://www.jbhe.com/features/49_college_admissions-test.html)
It's really pathetic that you "scientists" are abandoning your principle of objectivity simply because the evidence you find doesn't agree with your cherished political beliefs.
Racist troll is racist.
Methinks you doth protest too much. You spend a lot of effort to reinforce a belief that our culture very much wants to believe. That desire makes the belief suspicious, especially when you have to write so much and do such a dance to "explain" the evidence.
A persistent gap exists in IQ scores for self-reported racial categories. That gap has been around for a long time and holds even when statistically controled for things like SES. The cause of the gap is unknown. Differences linked to racial factors is one reasonable explanation.
That IQ is almost entirely due to genetics is well-established through twins studies and studies of adopted children. IQ is very stable over lifespan, suggesting that environmental factors to not much affect IQ. You need to get your beliefs in line with the evidence an not your ideology.
For all the âMZ twins separated at birthâ data, so what.
Those MZ twins also shared the same in utero environment where their brains grew from zero cells (there are no nerve cells when twinning happens) to 10^11 cells. What data is there to suggest that sharing an in utero environment is not important?
There is also the recent Nature paper which shows that human brains are mosaic.
In other words many (most?) of the cells in the brain don't even have the same genetic structure. The brain is comprised of many cells with different genomes.
Development and neurodevelopment are processes comprised of many non-linear coupled parameters. They exhibit the butterfly effect where differential effects early on can cause macroscopic effects later. This is the inherent outcome of systems of many, coupled, non-linear parameters (where many is more than 3). It is the butterfly effect writ large (or rather the flagellum effect), where the whoosh of a flagellum at one moment changes the diffusion and binding of transcription factors and chaperon proteins and changes the developmental trajectory.
No where is this more extreme than in the brain, where when neurons first start dividing, they activate retrotransposition so cells don't even have the same genome any more.
http://www.ncbi.nlm.nih.gov/pubmed/22037309
Now the whoosh of flagellum modulate where the retrotransposons latch on.
I suspect the extreme sensitivity of neurodevelopment to development (at the level of noise) is a âfeatureâ, to produce diversity in brain anatomy so as to produce diversity in cognition so as to produce diversity in cognitive abilities in a tribe where everyone is related (and so shares the same genes).
The tribe that had diversity in cognitive abilities, an expert in stone tools, wood tools, food tools, hunting tools, good visual cortex, good olfactory cortex, animal tools, weaving tools, language tools, etc, would out compete a tribe where everyone was the same.
The infant brain at birth is limited in size by the maternal pelvis. Evolution can't arbitrarily increase brain volume because it kills the mother. What evolution can do is produce diversity. In a tribe where everyone is related, evolution can't do it directly with genes, so evolution does it by making development exquisitely sensitive to the environment, at the level of noise.
This is why they can't find any genes for intelligence, autism, schizophrenia, etc. There aren't any, it is all development.
Hey, Alex, way to show you don't actually keep up with the literature, just keep a citation or two around for those times someone threatens your prejudices.
Try this. It's a bit more up to date: http://www.ncbi.nlm.nih.gov/pubmed/19418213
There is a very good paper out on the cause of male/female differences in mathematical ability.
DOI: http://dx.doi.org/10.1090/noti790
It is all social.
What is very interesting is that the difference correlates with gender equity. As gender equity goes down, female ability in math goes down, but as gender equity goes up, math ability for both boys and girls goes up.
It shows that having an educated mom with good economic status is good for both boys and girls. Who would have thought that?
Presumably having an educated mom with good economic status would be good for people of all ethnic groups because the data actually shows this.
Who would have thought that?
As I pointed out in the post, twins separated at birth are rarely separated at birth.
I think the other issues brought up by our need-to-believe friends have been addressed. And again, see also this: http://freethoughtblogs.com/almostdiamonds/2011/11/29/readings-in-iq-an… for more references.
Quote: As I pointed out in the post, twins separated at birth are rarely separated at birth.
Right, and that explains the discrepancy in IQ correlation between fraternal twins raised together and identical twins raised apart....
You're grasping at straws here. The idea of genetic IQ equality between genetically different human populations is just implausible, and all of the evidence gathered suggests that it is in fact implausible.
Black, whites, and Asians have genetically different mean IQs. If that fact upsets you, then I'm sorry -- most of us feel the same way. But denying it or lying about it is simply pathetic.
Alex, why do you think I'm upset because you are an ignorant racist?
This is the best I can find for identical vs. fraternal IQ studies:
http://www.newscientist.com/article/dn1520-iq-is-inherited-suggests-twi…
where they compared brain structures that can reasonably be linked to an intelligence measure. Random pairs of people would be expected to have no correlation, identical twins 95 to 100 per cent correlation, Fraternal twins 60 to 70 per cent correlation.
The correlation between members of a socially recognized racial group would be interesting to study.
What are the studies that show the efficacy of interventions made before the age of 5 to reduce differences in intelligence between socially recognized racial groups? Interventions in general seem to have poor results, but I am not sure about interventions made at young ages specifically.
[One irritation made in the discussion of intelligence is that mild results about the differences in races is used to support strong claims about the futility of social interventions, which hardly follows. Allow the moral imperative to correct historical injustice, allow the imperative for cost-benefit analysis, and then judge the efficacy of the intervention against those.]
Thanks for the post Greg. Hement Meta posted (unquestioning) a graph produced by Rushton a week or so ago. We protested, but he did not address its deficiencies, or take it down.
Good post, Greg! I'd also point out that not only does this idea not hold up to scrutiny, it is completely useless (and unnecessary) in explaining historical and present intergroup variation, which, compared to a lot of species, is tiny. Especially if you take into account the kind of inter-ethnicities genetic crossing that happen much more frequently than some people want to admit...
Not to be deliberately provocative, but white racists should be careful about these lines of argument. They might be right, they might be wrong, but in today's PC world, would the existence of mean IQ differences between different races matter at all? We're not bringing back colonialism, slavery, or paternal dictatorships, are we? So what's the practical purpose? Just to feel superior?
On the other hand, lots of IQ tests and studies seem to show that Asians score better than whites. Does that make them superior?
Given that the West has dominated the world for several centuries, that China, India, and the Asian Tigers are strong, independent economies, and growing faster than the West - aren't white racists inadvertently laying the groundwork for a theoretical justification for Asian subjugation and colonization of the West?
Our future Chinese (or Indian, or Pan-Asian) rulers can point to the flawed research of white racists, which show that sure, whites are smarter than blacks, but Asians are smarter than whites (oh, didn't you notice?), so white people should welcome benevolent Asian dictatorship. Irony, anyone?
Not to be deliberately provocative, but white racists should be careful about these lines of argument. They might be right, they might be wrong, but in today's PC world, would the existence of mean IQ differences between different races matter at all? We're not bringing back colonialism, slavery, or paternal dictatorships, are we? So what's the practical purpose? Just to feel superior?
On the other hand, lots of IQ tests and studies seem to show that Asians score better than whites. Does that make them superior?
Given that the West has dominated the world for several centuries, that China, India, and the Asian Tigers are strong, independent economies, and growing faster than the West - aren't white racists inadvertently laying the groundwork for a theoretical justification for Asian subjugation and colonization of the West?
Our future Chinese (or Indian, or Pan-Asian) rulers can point to the flawed research of white racists, which show that sure, whites are smarter than blacks, but Asians are smarter than whites (oh, didn't you notice?), so white people should welcome benevolent Asian dictatorship. Irony, anyone?
@Billy -
Very nicely done.
- pD
It's always both: nature and nurture. And measures of intelligence, like all fitness measures, depend on the environment. For example, some people panic and run at the slightest hint of danger. While we normally consider such behavior stupidly hysterical or cowardly, that was the most intelligent response for those near Fukushima Daiichi on 11 March 2011. It's about survival.
--bks
Given that a lot of things are heritable, it is interesting that the only one that seems to interest people with regard to intelligence is color. Why not sex, height or hair color?
Skin color is clearly an adaptive trait that has to do with vitamin D absorption which favors light skin when there is insufficient sun to get though dark skin, and Skin protection which favors dark skin in lots of sun. The more sun your ancestors lived in the darker they will generally be.
Intelligence is a human construct of little value. What is obvious is you we get very intelligent productive people of any skin hue, we also get really dumb ones of all skin hues. Trying to weasel out some sort of correlation with the huge cultural differences involved is a futile wast of time.
This is probably a lost cause, but let's give it a try...
Heritability is not genetic inheritance. It is scientifically incorrect and probably academically dishonest to assume or insist that a high heritability value means that something is genetic.
Heritability is defined as the portion of variance in a trait that is caused by additive genetic variance. So your point is incorrect by definition. Look it up.
If you apply these methodologies to what language someone speaks, the heritability for that trait is very high, much much higher than for IQ.
No it isn't. The real twin study method (as opposed to whatever you are talking about here) would compare the similarity in language ability for DZ and MZ twins, and find the latter to be just a bit higher than the latter (there are heritable conditions that affect language ability, but they are rare and explain little of the variance in language ability), thereby resulting in a very low heritability estimate.
For the readers who want to look up what real twin studies are about (and what their real problems are), you can start looking here.
For those who want to see examples of how to really fight scientific racism (i.e. by pointing the flaws in their "science", rather than making up imaginary ones, which just makes them look smarter in comparison), you can have a look at the work of JM Wichters.
And of course, my post came up all mangled. Just to be clear, paragraphs 2 and 4 in my rant above are quotations from Greg's post!
It isn't a surprise that MZ twins would share similarities in brain morphology. They share a genome, and they shared the in utero environment that they were in when that neuroanatomy developed from a single cell.
When they share both things 100.00000000000%, it isn't possible to attribute similarities to one or the other, no matter how much people want to.
toto, perhaps you should look into how "heritability" is actually determined. I suspect (hope) you would be surprised. Ditto for criticisms of twin studies. What someone is saying they're measuring is all well and good, but it's nothing if the methodology doesn't actually them you there.
I cannot believe this perennial hackneyed falsehood can resurrect with such periodic frequency every decade!
Alex is wrong for all the right reasons!
Of course IQ has a genetic component. If that is true, there is no a priori reason why race and IQ are not correlated.
For example â it would appear that the Ashkenazi Jewish population has a higher intelligence than their Gentile European neighbors.
http://tinyurl.com/73u3q4v
A cogent explanation for this Ashkenazi phenomenon would be a profound âfounder effectâ that can trace the entire Ashkenazi lineage back to only four women, based on mitochondrial DNA analysis and a stringent selection pressure for an Ashkenazi need to âsurvive by their witsâ in hostile urban settings given Gentile antipathy to Jewish integration in European society.
Dog breeders may compliment the innate intelligence of Golden Retrievers as opposed to the fixed stupidity of Irish Setters, but both âBreedsâ are highly inbred and as a genetic phenomenon have no prima facie ethnic equivalent in black vs. white populations. The problem is: âblackâ is not a âraceâ and by no means an inbred population like dogs or Ashkenazim.
Alexâs egregious ignoratio elenchi should have been preemptively aborted by the seminal paper published in 1977, separating once and for all confounding black/white nature/nurture variables with respect to IQ.
http://www.springerlink.com/content/u2177002257m7371/
Individuals identified as black can have increasing or decreasing admixture of âwhiteâ alleles in their genome without any concomitant effect on IQ.
The late Stephan Jay Gould phrased it best! âHuman Equality Is a Contingent Fact of Historyâ
http://www.stephenjaygould.org/library/gould_human-equality.html
Gould cites Richard Lewontin, â⦠if, God forbid, the holocaust occurs "and only the Xhosa people of the southern tip of Africa survived, the human species would still retain 80 percent of its genetic variation."
This defunct shibboleth of "lower black IQâ was slain decades ago and its persistent revivification can only be attributed to malicious racism or obtuse ignorance.
Anticipating howls of derisive rebutal - may I add:
Pushing this line of reasoning further: other âinbred whiteâ populations such as Albertan Hutterites or pockets of German communities in South America, all demonstrate a different founder effect; viz. lower IQs as an average compared to their neighbors.
J. B. S. Haldane wrote that "the motor bus, by breaking up inbred village communities, was a powerful eugenic agent".
Any Ashkenazi "advantage" will be soon lost as intermarriage becomes the norm.
The fact remains - any ethnic definition of "blacks", "whites", "Asians" and "coloured" demonstrate no difference in IQs.
daedalus: Yes, but as I mentioned in my post, the real twin studies method is to compare the similarity between MZ twins with the similarity between DZ twins. Notice that DZ and MZ twins share the same in-utero environment, so that won't affect the result. (Of course there is the complication of sharing the same placenta / amniotic sac or not, but since there are MZ twins of all configurations, that can be controlled for.)
Stephanie: well, from reading Greg's post, I believe that I understand what heritability means, and how twin studies work, a bit better than him. For example, I think the "language-would-show-high-heritability" bit demonstrates Greg's misunderstanding of what twin studies are. Because it wouldn't (MZ twins don't have largely more similar languages than DZ twins).
I'm not defending twin studies to the death here. Twin studies do have massive limitations. Mostly, these are the assumptions that MZ twins are genetically identical (they're not, in ways that matter medically), that they share equally similar environments with DZ twins (they probably don't) and that there is no gene-gene or gene-environment interaction (which of course can't be true in general, but can at least be controlled for).
What I'm saying is that Greg is making stuff up. The result is that "scientific racists" can point and laugh at those stupid libruls who can't do maths. Basically Greg is scoring own goal after own goal.
As I said, the proper way to fight scientific racists is to show the real (and quite massive) flaws in their "science". Like, say, routinely cherry-picking their data. Hence the link to JC Wicherts in my previous post. That's how you do it.
My apologies - my posts are in reverse order:
I cannot believe this perennial hackneyed falsehood can resurrect with such periodic frequency every decade!
Alex is wrong for all the right reasons!
Of course IQ has a genetic component. If that is true, there is no a priori reason why race and IQ are not correlated.
For example â it would appear that the Ashkenazi Jewish population has a higher intelligence than their Gentile European neighbors.
http://tinyurl.com/73u3q4v
A cogent explanation for this Ashkenazi phenomenon would be a profound âfounder effectâ that can trace the entire Ashkenazi lineage back to only four women, based on mitochondrial DNA analysis and a stringent selection pressure for an Ashkenazi need to âsurvive by their witsâ in hostile urban settings given Gentile antipathy to Jewish integration in European society.
Dog breeders may compliment the innate intelligence of Golden Retrievers as opposed to the fixed stupidity of Irish Setters, but both âBreedsâ are highly inbred and as a genetic phenomenon have no prima facie ethnic equivalent in black vs. white populations. The problem is: âblackâ is not a âraceâ and by no means an inbred population like dogs or Ashkenazim.
Alexâs egregious ignoratio elenchi should have been preemptively aborted by the seminal paper published in 1977, separating once and for all confounding black/white nature/nurture variables with respect to IQ.
http://www.springerlink.com/content/u2177002257m7371/
Individuals identified as black can have increasing or decreasing admixture of âwhiteâ alleles in their genome without any concomitant effect on IQ.
The late Stephan Jay Gould phrased it best! âHuman Equality Is a Contingent Fact of Historyâ
http://www.stephenjaygould.org/library/gould_human-equality.html
Gould cites Richard Lewontin, â⦠if, God forbid, the holocaust occurs "and only the Xhosa people of the southern tip of Africa survived, the human species would still retain 80 percent of its genetic variation."
This defunct shibboleth of "lower black IQâ was slain decades ago and its persistent revivification can only be attributed to malicious racism or obtuse ignorance.
Greg,
1-Would you be willing to comment on "the 10 000 year explosion". The authors present evidence for a higher IQ in Ashkenazi Jews (partly due to persecution).
2-They also argue that they are clear genetic differences between races. Most of the inter race variation is in non-coding DNA.
Thanks, gwen. Blogged.
toto, you're wrong. You may think you're right, but you're not. For example, tell me how "heritability" is determined in practice.
Further to my last post, from the 10 000 year explosion website:
These different subsistence ecologies are not only products of evolution and natural selection, they are also important contexts for it. If belligerent violent warriors, killers, have a reproductive advantage as the do among the Yanomamo of the Amazon basin (Chagnon 1988) then over a time scale of centuries males will become better and better at being belligerent and violent. If instead the social system favors white collar skills, like the niche of northern European Jews in Medieval times, intelligence and other related skill will increase. Centuries of peasant farming should select for being a good peasant farmer and related abilities. A system with a high interest rate, social stability, and the rule of law should select for the ability to defer rewards, against violence, and in favor of the ability to work hard. Gregory Clark (2007) suggests that precisely these circumstances in Medieval Europe led to the Industrial Revolution, that evolution forged a new kind of human that could sustain an industrial society.
Horace, the problem with your hypothesis about the Ashkenazi having a higher intelligence because of being an inbred population just happens to be false.
http://www.ncbi.nlm.nih.gov/pubmed/20798349
The Ashkenazi have greater genetic diversity than Europeans.
Daedalus2u,
the argument is not that the Ashkenazi are inbred, but that high IQ has been selected for. The paper that you cite concludes
"admixture and selection have also strongly influenced its current genetic makeup."
It doesn't seem like anyone's brought up the concept of IQ itself...maybe it's just that these kinds of tests are the best way we have to quantify intelligence, but they definitely have their flaws. The concept of intelligence is either too loosely defined to be tested, or so strictly defined that I'm not sure it's testing the human mind as much as the level of functionality of an undiscovered nub on the prefrontal cortex.
The idea may be to measure a person's aptitude for learning, but in reality, you have to have learned a reasonable amount beforehand. This is problematic especially for people who aren't non-native English speakers, for example, who then might have problems with the nuances of verbal sections. Of course, the socioeconomic factors leading to a lackluster education and/or desire to learn are the most visible weaknesses in the IQ construct, but cultural bias within the exam itself doesn't help either.
As for Asians topping IQ measurements, that has to be related to the educational system's focus on beating tests over there. I know there've been a few culture clash problems in US universities (with the influx of Chinese students in particular) - one student in a New England university memorized an entire Wikipedia article and wrote it from memory for an in-class essay. Performance without substance behind it is hollow, I think. It's definitely impressive, but after a certain point the kind of reasoning and understanding that IQ tests ask for just get twisted into finding shortcuts. Unless that is the pinnacle of human intelligence, of course, in which case I'll go hide under a rock.
daedalus2u
You misread the paper! http://www.ncbi.nlm.nih.gov/pubmed/20798349
Of course the Ashkenazim had an unusually high admixture of allelic input spanning Europe, the Middle East and the length of the Silk Road!
And let us remember that the first European ghettos for Ashkenazim were essentially gated communities for a privileged wealthy elite. The first ecclesiastically inspired backlash against Jews happened relatively late.
http://www.amazon.com/Yiddish-Civilisation-Rise-Forgotten-Nation/dp/140…
The fact remains - the Jewish population of Europe still endured significant bottlenecks while simultaneously being banned from making a living by owning land or belonging to guilds.
The Ashkenazim were forced to survive in urban settings and while the Gentile population of these cities could replenish urban populations with new recruits from the countryside - the Jews could not.
That would explain why a series epidemics and pogroms created a series of significant bottle-necks magnifying a founder effect.
Back to "Black IQ": The black population as a whole (whatever that means) never endured any such "bottle-necks". Therefore the âBlack IQ Bell Curveâ would be no different than the general population as a whole.
Meanwhile the Ashkenazi IQ advantage is diminishing as inter-marriage becomes the norm.
Eg. Wealth.
Bred, Inbred, Bottleneck, Selection are essentially synonyms. Fact remains, it does.
My apologies for misdirecting comments.
My last rebutal should have been addressed to Horace and not to Daedalus2u
re: "...The truth is, that there are many things that could have a high heritability value but that we know are not genetic, so we don't make a heritability estimate."
In fact - exactly just such estimates were successfully made back in the 1970s.
Individuals identified as black can have increasing or decreasing admixture of âwhiteâ alleles in their genome without any concomitant effect on IQ.
In other words: "blacks" can be more or less cyptically "white" as measured by blood antigen allelles.
An increased admixture of "white" alleles did not translate into enhanced IQ - while all other confounding factors were accounted for.
http://www.springerlink.com/content/u2177002257m7371/
It still amazes me that such racist sophistry can still persist!
re: Greg Laden's "Bred, Inbred, Bottleneck, Selection are essentially synonyms. Fact remains, it does."
To paraphrase Wolfgang Pauli - you are so off base - you are not even wrong anymore!
There are many DIFFERENT mechanisms for evolution and FYI: they are NOT "synonyms"!
Janie - AMEN!
A quote generally attributed to Binet when asked for an objective definition of "intelligence":
"intelligence is what my test measures"
As I said, this issue raises ideological and political issues that blind people to the scientific information (even if they can understand that information, which most can't). The authors of "The Bell Curve" were prevented from speaking and their ideas rejected mainly on ideological grounds. Scientific discussion must be open and we must accept what the data are telling us. Such scientific information never suggests that people lose their rights or be discriminated against. Critical thinking would also indicated that individuals can't be judged based on means of groups, especially when such groups are more or less constructions of humans.
That said, most people commenting do not know what they are talking about. They are saying the same old ideological dodges instead of finding out the facts and applying critical thinking and scientific reasoning (including the blog author).
Arguments over intelligence are muddled because the definition of intelligence is muddled. Cognitive ability (talent) is not separated from knowledge (learned information) in many definitions. Of course definitions of intelligence that include knowledge have a large nurture component. We have several good multi-dimentional measures of cognitive ability (which tend to be positively correlated) that minimize the effect of learned information. Such measures show a racial gap. If you think racial gaps have no genetic basis, then try to engage in a (scientifically( reasonable debate about the evidence.
"Cognitive ability has a substantial genetic component and more than 15 candidate genes have been identified over the past 8 years." That quote comes from an article cited above.
No one study can show that differences in math performance of genders are "all social". Science cannot prove anything, especially with one study. Evidence (of varying quality) is provided by studies. I'm not sure what gender has to do with this discussion anyway.
Of course, far be it from you, Rob, to actually deal with the scientific arguments made here or in response to The Bell Curve. It's ever so much easier to note that there are some people making political comments than to address the substantial criticism.
The authors of "The Bell Curve" were prevented from speaking and their ideas rejected mainly on ideological grounds.
That is not true at all. Their ideas were mostly ACCEPTED for ideological reasons by those who accepted them, and rejected on scientific grounds by those who rejected them.
Rob C.: "The authors of "The Bell Curve" were prevented from speaking and their ideas rejected mainly on ideological grounds. Scientific discussion must be open and we must accept what the data are telling us. Such scientific information never suggests that people lose their rights or be discriminated against."
A full review of the history of intelligence testing, the use of IQ tests, and the attempts to establish a genetic basis for intelligence, reveals that the topic of racial differences in IQ has been central in the psychological investigation of intelligence for the past hundred years.
Researchers such as Murray and Hernstein (Bell Curve), Arthur Jensen, and J. Phillipe Rushton, have had every opportunity to pursue their inquiries into race and IQ while holding academic posts, have had their findings published in scholarly journals, and their arguments have been given the same scientific scrutiny any valid research would be subjected toâthat is, their research has been taken seriously, not suppressed.
To casually suggest that there has been a concerted effort to stifle research about race and IQ, for political reasons, is simply false.
Claims of a genetic/racial basis for variance in IQ scores have simply not held up to scrutinyâ the evidence is not there, and the research used to support these claims has been shown flawed.
There are few researchers pursuing the race-IQ hypothesis because it has not led the field anywhere productive, not because of a taboo.
If you are interested, Iâve included links to some salient scholarly articles:
http://www.le.ac.uk/psychology/amc/scieraci.pdf
http://www.pitt.edu/~machery/papers/The%20concept%20of%20race_machery_F…
http://diversity.umsl.edu/documents/W07_Guess_article_s6.pdf
http://www.sanchezlab.com/pdfs/ShihetalCDEMP.pdf
http://www.stat.columbia.edu/~gelman/stuff_for_blog/flynn.pdf
Actually, nearly a majority of the scientific community endorses the idea of genetic IQ differences between blacks and whites.
According to a survey by Synderman and Rothman, 46% of scientists believe that genes play a role in the black-white IQ gap. Conversely, only 15% believe genes are not involved. (The rest were agnostic at that point.)
However, the authors noted that the media tend to present a distorted view of the race and intelligence debate, giving excessive coverage to the tiny minority who argue against genetic differences. (Source: The IQ Controversy, the Media and Public Policy)
So, to correct Greg Laden's statement: The Bell Curve's findings were accepted for scientific reasons and rejected for ideological reasons.
And that jibes with what I've observed about the debate: Those who argue against the genetic component are far more emotionally invested in the debate because they seem to believe that dignity of millions of people depends on the verity of their views.
I think that, regarding heritability, if it were true (heritability in this sense meaning that this is mostly genetic variation that produces the phenotype), than it would instantly give us a very interesting fact about the phenotype: it is not selected for during evolution. Indeed, selected characteristics translate into less genetic variation quite rapidly within populations. If that many genes are influencing intelligence, then it does not seem to be of importance to natural selection and evolution of the species in general. We should thus not care about it.
Amazingly, racists often take evolutionary arguments very seriously (because they also need a supremacy scale and struggle for life concept), but this one. But this one...
Maybe IQ is indeed much genetic, afterall. And people ever looking for this argument have inherited the bad genes. Those genes that prevent use of thinking and exploring consequences yet only of their own cherished concepts.
Carlos: ânearly a majority of the scientific community endorses the idea of genetic IQ differences between blacks and whites.â
Thatâs quite a claim-- I donât think Snyderman and Rothman would say that.
Perhaps, you simply had read a reference to this article in a site devoted to the âcontroversyâ over the political suppression of the link between race and IQ, when you had no knowledge of the actual survey at all
You might want to read source material before assuming you know something about the subject:
http://kodu.ut.ee/~spihlap/snyderman@rothman.pdf
What did Snyderman and Rothman actually say? Hereâs the salient bit:
âThe source of black-white difference in IQ. This is perhaps the central question in the IQ controversy. Respondents were asked to express their opinion of the role of genetic differences in the black-white IQ differential. Forty five percent believe the difference to be a product of genetic and environmental variation, compared to only 15% who feel the difference is entirely due to environmental variation. Twenty-four percent of experts do not believe there are sufficient data to support any reasonable opinion , and 14% did not respond to the question. Eight experts (1%) indicate a belief in an entirely genetic determinationâ. (pg. 141)
******
So, would you like to start with the problems in the nature and execution of this survey as âevidenceâ that a large percentage of the scientific community believes there is a genetic basis for racial differences in IQ, or the problems in your absurd characterization (â46% of scientists â) .
They received completed surveys from 661 âpsychologists and educational specialists with expertise in areas related to intelligence testingâ; somehow you interpret that to mean ânearly half the scientific communityââlike, what, biologists, geneticists, anthropologists? Also note that this was a survey of the opinions of those involved intelligence testing in the mid 1980âs-- this represents a consensus of âthe scientific communityâ now?
In any case, 1% of the 661 (8) felt IQ was entirely a product of genetics, and 45% (about 320) thought it was some combination of genetics and environment.
Thereâs your scientific communityâ328 psychologists in 1987.
Interestingly, if you read the article carefully, youâll find that that Richard Herrnstein (Mr. Bell Curve himself) is credited for assistance in developing the survey questions. Any chance Dr. Herrnstein had an interest in finding âexpertâ support for his theories?
And this leads you to say Greg is wrong?
Letâs try addressing the fundamental problems with any effort to establish a genetic basis for race and IQ:
From: http://www.councilforresponsiblegenetics.org/pageDocuments/XT0UW7SVHY.p…
Problem 1: Ainât no such biological entity called âraceâ:
âThe gene with highest frequency of between-group variation is one that influences skin pigmentation in humans and other organismsâthe SLC24A5 gene. 19 One version of this gene has been found in 98 to 100 percent of people in European population samples studied, but a different version of this gene has been found in 93 to 100 percent of people sampled from parts of Africa, East Asia and the Americas. Interestingly, over half of the African-Americans studied have either one or two copies of the gene variant commonly found in European populations. 19,20
To the extent that genes underlie pigmentation, perhaps the most visible of human differences, we should expect that some of those genes will have quite different frequencies among people of different skin color. What may be surprising is that pigmentation is genetically very complex. At least five different genes strongly influence skin pigmentation, and there are hundreds of other genes that may play a minor or occasional role. 19 Because of this complexity, scientists cannot use variants of pigmentation genes as a means of racial classification. There are no pigmentation gene variants that are found only and always in âwhite peopleâ but not in people of other racial groups.â
Problem 2: Ainât no such thing as IQ:
âJust as there is no unitary definition of race, there is no agreed upon or single definition of intelligence. One aphorism holds that intelligence is what intelligence tests measure. Psychometricians argue that intelligence tests measure reasoning skills, although the tests also measure knowledge. 41 Some innovative scholars have developed theories of emotional intelligence and multiple intelligencesâmultiple types of cognitive function that are valuable and measurable, and that may manifest differently in different contexts. 24,42-44 The typical IQ test does not measure multiple intelligences; instead, the test produces a single intelligence quotient (IQ).â
So, Carlos, to sum upâ you believe in two illusory constructsârace and IQ--, and then posit that both are products of genetics.
But the reason this is not taken seriously is âpoliticsâ?
Or some people just canât surrender cherished beliefs about their natural superiority because of their skin pigmentation.
I am shocked that anyone would represent a survey among psychologists and education specialists a quarter century ago on genetics as being representative of what scientists studying genetics would think today.
phillydoug,
Race is based on ancestry -- nothing more, nothing less. There are observed mean differences among the different races (or populations -- whatever you want to call them) in genetically influenced traits. Skin color is an obvious one; another appears to be brain size.
As for your second argument: I'm not quite sure how you can say that IQ doesn't exist because, well, it clearly does exist. If you were bit a brighter, you might argue that it doesn't truly represent intelligence or that it's biased or whatever -- but to say that it doesn't exist is laughably stupid.
Whatever it measures, IQ captures something that is strongly correlated with logical reasoning, numerical reasoning, verbal reasoning, visuospatial reasoning, academic success, career success, and pretty much everything else that we consider good in industrialized civilizations. If you don't have a high IQ (or if a certain group doesn't) -- that's a huge disadvantage. So whether IQ really captures our notion of intelligence or not, it's still very important, and a potential genetic difference in it among blacks, whites, and Asians is too significant to ignore.
Carlos: "IQ captures something that is strongly correlated with logical reasoning, numerical reasoning, verbal reasoning, visuospatial reasoning, academic success, career success, and pretty much everything else that we consider good in industrialized civilizations."
You really have a penchant for sweeping generalizations based on limited (or absent) knowledge. Keep up the good work!
"Skin color is an obvious one; another appears to be brain size."
Now we're getting somewhere-- 'brain size' differs along with skin color does it? Consistently, predictably? Suprising that you offer no support whatsoever for your claims, nor seem to have bothered to respond to the scholarly articles I posted links to. Why would you? Your worldview is hermetically sealed.
No,Carlos, no scientist claims that there is race - brain size co-variation; back in the days of the Confederate south and the British Empire some did. You might want to update your data by about a hundred years.
Daedalus: "I am shocked that anyone would represent a survey among psychologists and education specialists a quarter century ago on genetics as being representative of what scientists studying genetics would think today. "
Shocked? I'm surprised Carlos made reference to anything purporting to be research at all. You're much too willing too assume that racists are prepared to have good faith discussions, and actually consider evidence.
With his brain size remark, I think we're established that Carlos doesn't possess much in the way of critical thinking, or awareness of any developments in neuroscience in the last, what, century?
Hey Carlos, if you had any interest in educating yourself (I'm doubtful), along with reading the materials I previously posted links for, try this (it's a briefer, easier to read piece, so you might find it more accessable):
http://www.rcgd.isr.umich.edu/news/Nisbett.ScienceNow.04_2011.pdf
"New research concludes that IQ scores are partly a measure of how motivated a child is to do well on the test. And harnessing that motivation might be as important to later success as so-called native intelligence. Researchers have long debated what IQ tests actually measure, and whether average differences in IQ scores--such as those between different ethnic groups--reflect differences in intelligence, social and economic factors, or both. The debate moved heavily into the public arena with the 1994 publication of The Bell Curve by Richard Herrnstein and Charles Murray, which suggested that the lower average IQ scores of some ethnic groups, such as African-Americans and Hispanics, were due in large part to genetic differences between them and Caucasian groups. That view has been challenged by many scientists. For example, in his 2009 book "Intelligence and How to Get It," Richard Nisbett, a psychologist at the University of Michigan, Ann Arbor, argued that differences in IQ scores largely disappear when researchers control for social and economic factors.
Brain size is an interesting one. Women have on average a smaller brain than men but they sure don't have any less intelligence! It is true the brain mass/body mass ratio of a woman is as high or higher than a man's but I cannot see how the lighter weight of the woman would be less demanding on the brain. If this were so all really heavy people would be Soo dumb!
Carlos: "Race is based on ancestry -- nothing more, nothing less. There are observed mean differences among the different races (or populations -- whatever you want to call them) in genetically influenced traits. Skin color is an obvious one"
So, Carlos, which part of this (from the above post) was unclear to you--
'At least five different genes strongly influence skin pigmentation, and there are hundreds of other genes that may play a minor or occasional role. 19 Because of this complexity, scientists cannot use variants of pigmentation genes as a means of racial classification. There are no pigmentation gene variants that are found only and always in âwhite peopleâ but not in people of other racial groups.'
Hmm... you didn't seem to actually address this. Not even a passing mention that, well, there is no support for your claim that 'Race is based on ancestry -- nothing more, nothing less.'
This actually is a shift in terminology-- you seem to want to blur the distinction here, 'ancestry' has been substituted for 'genetic', which I guess is a shrewd move, since you have no apparent understanding of genetics, and you really wouldn't want to acknowledge the science, since it shows your argument is specious. But you keep on trying.
Now, please elucidate-- with any support you can muster from any scientific source you can cite (I notice you haven't even attempted this since your last effort at citing a scholarly reference was shown patently absurd)--
"There are observed mean differences among the different races (or populations -- whatever you want to call them) in genetically influenced traits."
Really cool terminology shift here too-- 'populations' substitued for 'races'; perhaps you've decided that your best option is to try and slip away from each claim once it's been scrutinized.
C'mon, Carlos, stick to your guns!
You think race has some biological meaning. Find me a biologist, geneticist, anthropologist, anywhere, who thinks that. Back up the claim.
You think IQ measures this entity called 'intelligence'-- show me a widely accepted definition of general intelligence, with consensus support from psychologists, neurologists, cognitive scientists. Back up the claim. Something from this century, if you don't mind.
You say intelligence varies predictably with skin color (another reason you might want to avoid tanning, I suppose).
Point to some credible evidence.
**********
Race is a social designation, and racial categories were devised by Europeans to justify all sorts of horrendous behavior; not surprisingly, racists have spent decades trying to establish some shred of biological evidence to support what they already believe-- low melanin makes them naturally smarter, superior, all around better.
That's really want you want to hear, right? An acknowledgement you were born superior?
The above exchange in comments is so very tiresome. It's interesting, Greg, that you don't even bother to debunk the two core assumptions involved in this debate: that both "race" and "general intelligence" (as measured by IQ tests) exist. That's deeply sad, really. Both don't exist and, because of that, the entire argument you're opposing falls completely apart.
So why don't you just debunk those two core assumptions right off-the-bat? Because basically everyoneânot just people who are inclined toward racist beliefs about variations in intelligenceâbelieves those two things exist and are unquestionable. Conservatives, liberals, the educated and the ignorant, the scientifically literate and those who are not...everyone, really.
For years now, I've taken pains at most every opportunity to debunk the common notion of race (that is, genetic population divergences which correspond to superficial features of anatomy) being scientifically valid. And I've gotten the strong impression that even people who would be friendly to learning thisâprogressive and scientifically literate peopleâfind it just too difficult to swallow. Everyone "knows" that race is real. Many people have heard of anthropologists and forensic specialists being able to identify the race from skeletal remains. Most people know of diseases that are genetically linked to a particular race. Of course races exist, right? Only someone very ideologically motivated would deny what almost everyone, across the political spectrum, accepts as true...is what people inevitably think.
Yet the essential notion about the biology of race is and has been easily disproved by population genetics studies. It just doesn't mean what people think it means. The problem is that clearly, it is biological in some sense. Getting people past that is really quite difficult. In my opinion, until it makes it into school textbooks that race doesn't mean what people have thought it means, it's going to keep meaning something that is untrue.
Race is real, per the New York Times:
Historians often assume that they need pay no attention to human evolution because the process ground to a halt in the distant past. That assumption is looking less and less secure in light of new findings based on decoding human DNA.
Multimedia
Genetic Differentiation in Modern HumansGraphic
Genetic Differentiation in Modern Humans
People have continued to evolve since leaving the ancestral homeland in northeastern Africa some 50,000 years ago, both through the random process known as genetic drift and through natural selection. The genome bears many fingerprints in places where natural selection has recently remolded the human clay, researchers have found, as people in the various continents adapted to new diseases, climates, diets and, perhaps, behavioral demands.
A striking feature of many of these changes is that they are local. The genes under selective pressure found in one continent-based population or race are mostly different from those that occur in the others. These genes so far make up a small fraction of all human genes.
A notable instance of recent natural selection is the emergence of lactose tolerance â the ability to digest lactose in adulthood â among the cattle-herding people of northern Europe some 5,000 years ago. Lactase, the enzyme that digests the principal sugar of milk, is usually switched off after weaning. But because of the great nutritional benefit for cattle herders of being able to digest lactose in adulthood, a genetic change that keeps the lactase gene switched on spread through the population.
Lactose tolerance is not confined to Europeans. Last year, Sarah Tishkoff of the University of Maryland and colleagues tested 43 ethnic groups in East Africa and found three separate mutations, all different from the European one, that keep the lactase gene switched on in adulthood. One of the mutations, found in peoples of Kenya and Tanzania, may have arisen as recently as 3,000 years ago.
That lactose tolerance has evolved independently four times is an instance of convergent evolution. Natural selection has used the different mutations available in European and East African populations to make each develop lactose tolerance. In Africa, those who carried the mutation were able to leave 10 times more progeny, creating a strong selective advantage.
Researchers studying other single genes have found evidence for recent evolutionary change in the genes that mediate conditions like skin color, resistance to malaria and salt retention.
The most striking instances of recent human evolution have emerged from a new kind of study, one in which the genome is scanned for evidence of selective pressures by looking at a few hundred thousand specific sites where variation is common.
Last year Benjamin Voight, Jonathan Pritchard and colleagues at the University of Chicago searched for genes under natural selection in Africans, Europeans and East Asians. In each race, some 200 genes showed signals of selection, but without much overlap, suggesting that the populations on each continent were adapting to local challenges.
Another study, by Scott Williamson of Cornell University and colleagues, published in PLoS Genetics this month, found 100 genes under selection in Chinese, African-Americans and European-Americans.
In most cases, the source of selective pressure is unknown. But many genes associated with resistance to disease emerge from the scans, confirming that disease is a powerful selective force. Another category of genes under selective pressure covers those involved in metabolism, suggesting that people were responding to changes in diet, perhaps associated with the switch from hunting and gathering to agriculture.
Several genes involved in determining skin color have been under selective pressure in Europeans and East Asians. But Dr. Pritchardâs study detected skin color genes only in Europeans, and Dr. Williamson found mostly genes selected in Chinese.
The reason for the difference is that Dr. Pritchardâs statistical screen detects genetic variants that have become very common in a population but are not yet universal. Dr. Williamsonâs picks up variants that have already swept through a population and are possessed by almost everyone.
The findings suggest that Europeans and East Asians acquired their pale skin through different genetic routes and, in the case of Europeans, perhaps as recently as around 7,000 years ago.
Another puzzle is presented by selected genes involved in brain function, which occur in different populations and could presumably be responses to behavioral challenges encountered since people left the ancestral homeland in Africa.
But some genes have more than one role, and some of these brain-related genes could have been selected for other properties.
Two years ago, Bruce Lahn, a geneticist at the University of Chicago, reported finding signatures of selection in two brain-related genes of a type known as microcephalins, because when mutated, people are born with very small brains. Two of the microcephalins had come under selection in Europeans and one in Chinese, Dr. Lahn reported.
He suggested that the selected forms of the gene had helped improved cognitive capacity and that many other genes, yet to be identified, would turn out to have done the same in these and other populations.
Neither microcephalin gene turned up in Dr. Pritchardâs or Dr. Williamsonâs list of selected genes, and other researchers have disputed Dr. Lahnâs claims. Dr. Pritchard found that two other microcephalin genes were under selection, one in Africans and the other in Europeans and East Asians.
Even more strikingly, Dr. Williamsonâs group reported that a version of a gene called DAB1 had become universal in Chinese but not in other populations. DAB1 is involved in organizing the layers of cells in the cerebral cortex, the site of higher cognitive functions.
Variants of two genes involved in hearing have become universal, one in Chinese, the other in Europeans.
The emerging lists of selected human genes may open new insights into the interactions between history and genetics. âIf we ask what are the most important evolutionary events of the last 5,000 years, they are cultural, like the spread of agriculture, or extinctions of populations through war or disease,â said Marcus Feldman, a population geneticist at Stanford. These cultural events are likely to have left deep marks in the human genome.
A genomic survey of world populations by Dr. Feldman, Noah Rosenberg and colleagues in 2002 showed that people clustered genetically on the basis of small differences in DNA into five groups that correspond to the five continent-based populations: Africans, Australian aborigines, East Asians, American Indians and Caucasians, a group that includes Europeans, Middle Easterners and people of the Indian subcontinent. The clusterings reflect âserial founder effects,â Dr. Feldman said, meaning that as people migrated around the world, each new population carried away just part of the genetic variation in the one it was derived from.
The new scans for selection show so far that the populations on each continent have evolved independently in some ways as they responded to local climates, diseases and, perhaps, behavioral situations.
The concept of race as having a biological basis is controversial, and most geneticists are reluctant to describe it that way. But some say the genetic clustering into continent-based groups does correspond roughly to the popular conception of racial groups.
âThere are difficulties in where you put boundaries on the globe, but we know now there are enough genetic differences between people from different parts of the world that you can classify people in groups that correspond to popular notions of race,â Dr. Pritchard said.
David Reich, a population geneticist at the Harvard Medical School, said that the term âraceâ was scientifically inexact and that he preferred âancestry.â Genetic tests of ancestry are now so precise, he said, that they can identify not just Europeans but can distinguish between northern and southern Europeans. Ancestry tests are used in trying to identify genes for disease risk by comparing patients with healthy people. People of different races are excluded in such studies. Their genetic differences would obscure the genetic difference between patients and unaffected people.
No one yet knows to what extent natural selection for local conditions may have forced the populations on each continent down different evolutionary tracks. But those tracks could turn out to be somewhat parallel. At least some of the evolutionary changes now emerging have clearly been convergent, meaning that natural selection has made use of the different mutations available in each population to accomplish the same adaptation.
This is the case with lactose tolerance in European and African peoples and with pale skin in East Asians and Europeans.
http://www.nytimes.com/2007/06/26/science/26human.html?pagewanted=all
Did you actually read the article that you just posted as a comment?
I don't know if it's really significative as almost anything on this sort of debate can be interpreted both ways, but I've found it interesting:
"Despite vast differences in the genetic code across individuals and ethnicities, the human brain shows a "consistent molecular architecture," say researchers supported by the National Institutes of Health"
http://www.nih.gov/news/health/oct2011/nimh-26.htm
The genes coding for the molecular stuff of the brain prob. Don't vary that much.
The same race has a genetically determined difference in intelligence too.
It's why we don't all get the same grade.
(this is rather like asking: Is education wasted on women? The answer, in profit/cost is "No". But the same answer would be given for the same reasons if the question was: Is education wasted on men? Or dolphins, chimps, squirrels, slugs and anything else we try to teach.)
Wow wrote: "The same race has a genetically determined difference in intelligence too.
It's why we don't all get the same grade."
This is one of the many reasons why we don't get all the same grades.
Regardless of this remark, even though most authors who put forward the idea of innate average differences in intelligence between groups mention that there is great within-race genetic variation influencing IQ, it's something almost completely neglected by those who defend such "genetic realities" as something socially significant over the blogosphere and discussion boards.
I recall the recent case of "heyrucka", who actually sort of stressed the fallacy (I mean, not stressing that it is a fallacy, but laying down the faulty reasoning explicitly, instead the seemingly more common vague unconscious assumption), sating something in the lines of "IQ is inherited, and does not matter so much the individual IQ, but the IQ of the race you belong."
When I heard that I was somewhat startled and felt like just yelling "WHY? How come it makes any sense at all?" It's somewhat as if it were some sort of team competition in their minds.
If these guys were serious, we should not exepct that much emphasis on race, since the bulk of the low IQ people on largely white countries is made of white people. This is in most cases not even a minimal concern, but completely overlooked, and given that most marriages are within-race it would be reasonable to expect it to be of larger concern than interracial marriage/miscegenation.
My guess is that they are not that interested in proposing "racially blind" incentives or disincentives for fertility according with IQ because they can't accept the implicit "exchange" of the offspring of low-IQ white people for the offspring of high or average IQ black people. Low IQ white people having more offspring is something they probably desire as it results not only in keeping a white majority, but also in a not particularly bright mass that they could more easily influence. I was a bit suspicious of this even before I've heard of those movements promoting that people should have more children as a way to outnumber incoming immigrants, which I see almost as a confirmation.
This is one of the many reasons why we don't get all the same grades.
Or not. In order to be on the list of causes, it can't just be something that someone needs to be true. It needs to be demonstrated.
Your argument seems to be solely directed
at criticizing the hereditarian argument.
But you have not shown why there cannot be
a significant difference in the distribution of genes
underlying IQ between populations.
Agreed that all humans are more closely related
Than two bands of chimps living on different
sides of the river in Africa.
Despite this human populations show significant
differences in those genes which can vary between
siblings.
IOW we are all brothers---but we're not
Identical twins.
Is there a modern day example of an African country or African province anywhere in the world that has political and social stability, functional infrastructure, that makes any contributions to the arts or sciences? Most images I have seen in American media of an African country or African city abroad is one of ignorance, poverty, corruption, deterioration, rape and murder, much like our inner cities in the US. I don't care about variables like IQ, spurious correlations, environmental factors. I just want to know if any single black culture somewhere on our planet successfully thrives on its own without the media stereotyped violence, ignorance and brutality. I want this evidence to show some of my racist co-workers they are just that, racist bigots. But as I have tried to defend my position, well, I require some real evidence of a successful black community, not just stand alone musicians, comedians, sports stars or any black who is individually successful in entertainment...NOT individuals, but just one fair example of ANY black community. Thank you and God Bless.
@Honest Abe:
Your questions are absurd, as the disposition of African countries or black communities is irrelevant to the question of human intelligence. Nevertheless, as you are on the Internet, you can easily Google "affluent black communities" or "GDP per capita by country" or "Global Peace Index." You'll find many black communities in the U.S. which are comparable to the finest white communities. And you'll find countries in Africa as well as the Caribbean that are ahead of white and Asian countries in terms of multiple wealth and quality of life indices. In many instances these black countries are significantly ahead of many white and Asian countries.
But I'm struck that you would show up to a debate on intelligence to make such a stupid argument in the first place. I'm assuming your genetic heritage is Northwestern European. Do you realize what kind of barbarous and savage backwater that part of the world has been for 99% of human history? Shall we go back to antiquity or the middle ages and ask why those white Europeans are so backwards, savage and stupid?
Btw, Africa is a very big place. Saying that the entire continent is characterized by certain pathologies would be like saying that all white Europeans rape little boys.
I see a lot of tension here. You all must look at this from a non bias scientific perspective that is in line with the expectations and observations that support evolution. Evolution is change in allele frequency over time. Through gene flow and genetic drift two separate populations will evolve differently and given enough time they will indeed become different species. This is seen with every other species and Homo Sapien Sapien (humans) are not exempt. Dog breeds vary in many different traits (intelligence, speed, stamina, build, endurance, aggressiveness, height, eye color, hair color and numerous others). In these instances we selectively breed dogs based on the desirable traits that we wish to build on. We take the place of natural selection in this instance. We could do this same thing with any species on this planet if we choose. Human beings are not exempt. The differences found in populations from continent to continent or even islands for that matter are not just skin deep. To say such a thing goes against the very fabric of evolution. To say that we are different in speed, stamina, build, endurance, aggressiveness, height, eye color, hair color and numerous other traits while making intelligence exempt from the normal evolutionary processes where humans are concerned is completely false. The fact that we do so is due to the dangerous nature of this information. In truth, equality is really an idea born out of a fantastical Alice in Wonderland train of thought. This has no place in evolution. Equal means the same! I can assure you that no one on earth is the same. This only has a hint of truth when talking about equal rights. Race is really a term we use in place of breed. African's, Europeans, Asians, Indians are all different examples of various breeds. Natural selection will make certain traits desirable over others, thus two populations that are inhabiting different environments will not be the same. Even if the two populations are inhabiting the same environment, gene flow and genetic drift make it impossible for the two populations to end up being the same. To say anything different is really disputing evolution at its very core. Average brain sizes are indeed different in various "breeds" of human beings. The attempts to silence this or to discredit it do not make it any less true. The social ramifications of the information would be huge if it was accepted. If we gave scientists a group of humans I have no doubts that they could breed them to make one group less intelligent than another. It is a sure bet and it follows current evolutionary thinking to the letter. We could select desirable traits and breed humans just like we breed dogs. We will get the same results. The facts of evolution do not depend on what people want to believe. At the end of the day they are still facts. We can hide them, run from them, discredit them but that does not change what reality of the facts. We find the same with religion. When scientists find plenty of evidence that points to evolution and a earth that is billions of years old, what happens? The religious group denies the science if it conflicts with their beliefs regardless of the real facts or what the evidence points to. This is what is going on with the argument that I am commenting on. Emotion is getting in the way of logic. Denial of the truth is running rampant and discrediting an honest assessment of that truth based on the very facts that we use to back up evolution. If evolution is correct traits as well as intelligence will be different between various populations. That is just the way it is from an unbiased perspective. I believe that truth is paramount not socially accepted and distorted versions of it. If anybody who reads this can tell me that humans are exempt from what we observe in other species (even our own) and provide evidence to back up this claim from an unbiased source that can be scientifically verified you will have just proven that evolution is completely false or that we are not part of it. I then would suggest that you write a scientific paper on the matter and get it published because your name will be remembered for as long as human beings survive.
Joshua, how dare you attempt to school me on evolution with such a simplistic, inaccurate, and incomplete tl;dr diatribe.
You have a few correct points in here but you have failed to understand a couple of the most important concepts. First, "race" is subspecies, but you can say "breed" if you want. In order for there to be subspecies, there have to be genetic populations that follow the usual characteristics. For humans, this does not work out very well at all. In fact, the number of subspecies defined across zoology has dropped to a small fraction of what it once was (relative to number of species) not because they went extinct but because the concept was being overused, as you have overused it here.
Second, what we try to do in science, very often, is to identify, measure, then explain the cause of variation. There is variation across humans. What causes it? The inherited component turns out to be very small for most of the traits people speak of when they babble on about race. These differences are caused by other things. It takes very little work to demonstrate that, but if someone comes to the table assuming otherwise, it is often nearly impossible to convince them otherwise.
And, a common reaction to that, rather than learning, exploring more of the science, and rethinking one's preconceptions, is to turn the conversation into a diatribe about how the other person does not understand evolution or is basing conclusions on something like religion.
Like you just did.
Tell me how what I said is "inaccurate". I have more than a "few" correct statements. Also you say "There is variation across humans. What causes it? The inherited component turns out to be very small for most of the traits people speak of when they babble on about race. These differences are caused by other things." You ask, what causes it? This is simple Mendelian Genetics. It is known that skin color, eye color, hair color, height and stature are inherited. Intelligence will also vary in populations. "http://www.the-scientist.com/?articles.view/articleNo/40459/title/inher…" "http://newsroom.ucla.edu/releases/more-proof-that-intelligence-is-85134" "http://news.sciencemag.org/biology/2014/10/genes-dont-just-influence-yo…" "http://www.sciencedaily.com/releases/2009/03/090317142841.htm" Read some of these findings by scientists. "Inherited components" are turning out to be exactly what accounts for most of the "traits" people "babble" about when they refer to race. It is possible that you are behind the times? Or you have some reading to do. You are in disagreement of what I learned in college and what I learn by reading through various scientific journals. You say: "what we try to do in science, very often, is to identify, measure, then explain the cause of variation." Are you claiming that your a scientist or are you just a freelance writer? The very fact that you became angered at my comment is a sign that you have a lack of professionalism and are in need of a course on anger management. I suggest you do more reading and less typing.
Josh, you are in disagrement with what I teach in college! Checkmate. :)
Don't we all descend from Africa/? Mitochondria Eve lived in Africa. I don't think 200000 years would be enough time for evolution to create such a wide gap? No, evolution must be wrong evolutionary psychology leads the way!
http://www.unz.com/article/the-iq-gap-is-no-longer-a-black-and-white-is…
" No, evolution must be wrong "
Claim does not follow from the premise.
Someone really smart but born to a poor village in Botswana for example, has no teaching and no way to demonstrate their intelligence.
So their intelligence on any task we then set them will show them as "dumber" than someone just as smart but sent via the Ivy League path.
The society you live in and the options you get have a huge effect on "intelligence", and that evolves much faster since it mutates much more readily and in many more ways than genetics, which has to at least produce a viable living organism when it manages its mutation.
The genetic variation in humans is tiny. Outside Africa, the genetic variation between Innuit, Canadian, Australasian and Arab are less far than you can see between chimanzees, all considered the same species, not even subspecied.
Because the out of africa would produce such a strait genetic diversity, this is one of the reasons it's suspected to be correct. Yet within this very strict variation, you can see a huge change in the average height, life expectancy and visual appearance of these "races".
Inside Africa, they've been there for millions of years, hence a wider distribution, but still no more variation than you get within chimp tribes, none of whom are considered a different race of chimpanzee.
So we have two facts:
1) Little genetic difference can cause huge differences in what we perceive in the appearance of humans
2) Relatively large genetic differenes cause no difference in what we perceive in the appearance of chimpanzees.
Conclusion: Some other factor is the determinant, and it's not a genetic difference.
Some other factor to consider. Eating disorders that cause the sufferer to starve themselves will lose brain mass as the body converts more of their internal organs into energy to keep as much as possible going to try and survive starvation.
Is anorexia the expression of a genetic trait and nothing more? If you think not, then the drop in intelligence is not either. But that's a black swan to the claim that intelligence is inherited.
Likewise, if you never got to eat enough, your body will not build as much and as quickly (or keep what it got), and likewise if the diet is bad. And that body build-up includes the brain. Less developed brain, lower intelligence. Diet is genetic?
Advances in Intelligence Research What Should We Expect From the XXI Century?
https://www.cambridge.org/core/journals/spanish-journal-of-psychology/s…