Can the Black-White racial IQ gap in the US be environmentally explained?

[Chen019]

@Ibn_Warraq

Agreed. Race is a myth and while “black” and “white” may be useful cultural terms they’re not scientific and they’re not terribly meaningful biologically.

Wow. There have been so many debate threads on this. Try engaging some of those arguments before making inane comments that “race is a myth”. Just as race in other species is a myth too I’m sure :smack:

[Chen019]

@Evil_Economist

I also see the following (quote marks, but it’s a paraphrase): “mixed race children who lived with a white mother scored 11 points higher than mixed-race children who lived with a black mother. The black-white IQ gap at the time was 15 points”

And I notice from the footnote that the mixed-race children who grew up with a white mother (and liven in a 2-parent household) had an average IQ of 104.7.

That study right there seems to absolutely and completely destroy the “genetic” argument.

I don’t think you can resolve the issue either way on the basis of adoption studies to date. They appear to offer support for both genetic and environmental factors.

So there are many good reasons to doubt cultural explanations a priori, but a more direct test is available. One possible way to control for distinct ethnic values is simply to raise the children of higher or lower scoring racial backgrounds in another ethnocultural environment of purportedly different values. If ethnic differences are caused by ethnically different parents, as asserted by gene-disparaging psychologists such as Richard Nisbett, then such a test should settle the issue. The transracial adoption data we have so far doesn’t appear to support Nisbett.

One longitudinal study, the only one of its kind, of black children raised in white homes, showed that by highschool these adoptees scored no differently on IQ tests than African-Americans raised by their biological parents. Meanwhile three studies of Asians [1] raised in white families showed higher than average test scores. A problem with these latter three papers of Asian adoptees is that they didn’t use control samples of white adoptees. Did the Asian children just score higher because adoptees in general score higher?

A newer study published in the American Journal of Orthopsyciatry allows us to compare adopted white children with, at least small samples of, transracially adopted Asian children to try and answer this question. An advantage of this study is that it used data from the National Longitudinal Study of Adolescent Health which means it was able to compare developmentally mature adoptees in grades 7-12, instead of children at ages like 4 or 6 when differences are less stable. Comparing 350 white adoptees with 24 Asian transracial adoptees, and (a mere) 8 black transracial adoptees, the authors found differences on a number of different dimensions that went in the same direction they usually do, despite the controlled ethnic upbringing (lower scores mean better grades, less learning problems, less delinquency, and more self-esteem):

++++++++++++++++++++Asian Adoptees+++White Adoptees++Black Adoptees
Grades+++++++++++++++1.72 (A-)+++++++++++2.25 (B+)+++++++++2.67 (B-)
Learning problems+++++++1.06++++++++++++++1.12+++++++++++++1.34
Delinquency++++++++++++0.16+++++++++++++0.20++++++++++++++0.25
Self-esteem++++++++++++2.07+++++++++++++1.96++++++++++++++1.78

The small sample sizes cry out for a larger replication (along with the Scarr adoption study which only had 21 black children, but had the advantage of an additional 55 black-white mixed race children who fell in between the white and black children on all academic variables), and other aspects of this study are not compatible with other published studies (i.e. contrary to the Moore study, also used as cultural evidence by Nisbett, it also showed that adopted black children raised in black households performed similarly, even somewhat better than, the transracially adopted black children in this study). But still the differing levels of performance of the transracially adopted black and Asian in this study are compatible with other adoption experiments which show similar results, and casts further doubt on the theory that ethnic differences are due to differences in upbringing unique to separate American ethnic groups (further evidence for this was also demonstrated with another method by Rowe and Flannery who found no unique correlation patterns in the developmental data of different ethnic groups).

[Belowjob2.0]

@Chen019

Wow. There have been so many debate threads on this. Try engaging some of those arguments before making inane comments that “race is a myth”. Just as race in other species is a myth too I’m sure :smack:

False analogy. All modern humans belong to the same subspecies. We’re all one race, in biological terms.

[Belowjob2.0]

@Evil_Economist

This paper seems directly on point, but the version you linked to is very blurry and difficult to read; do you have a different link?

backintyme.com/rawdata/jencks01.doc

[Evil_Economist]

@Chen019

I don’t think you can resolve the issue either way on the basis of adoption studies to date. They appear to offer support for both genetic and environmental factors.

The entire block you posted appears to be from some guy’s blog.

The Wiki link you posted has the following statement:

In a 1998 article, Scarr wrote: … The results of the transracial adoption study can be used to support either a genetic difference hypothesis or an environmental difference one (because the children have visible African ancestry). We should have been agnostic on the conclusions.
…

Loehlin (2000) reiterates the confounding problems of the study and notes that both genetic and environmental interpretations are possible. He further offers another possible explanation of the results, namely unequal prenatal factors: "[O]ne possibility lies in the prenatal environment provided by Black and White biological mothers. The Black-Black group, of course, all had Black mothers. In the Black-White group, virtually all of the birth mothers were White (66 of 68). Willerman and his colleagues found that in interracial couples it made a difference whether the mother was Black or White: The children obtained higher IQs if she was White. They suspected that this difference was due to postnatal environment, but it could, of course, have been in the prenatal one

So, agreed, the study didn’t clarify anything. But that’s not good news for the “genetic” team; doesn’t this mean that the evidence for a genetic explanation is precisely…nothing?

[Evil_Economist]

@Belowjob2.0

backintyme.com/rawdata/jencks01.doc

Appreciate it, but this seems to be a Word document containing fuzzy pictures of the initial report.

[Evil_Economist]

@Evil_Economist

So, agreed, the study didn’t clarify anything. But that’s not good news for the “genetic” team; doesn’t this mean that the evidence for a genetic explanation is precisely…nothing?

Doing a bit of research, I find the following from the Minnesota Transracial Adoption Study’s author (discussing The Bell Curve):

Tellingly, the authors fail to address evidence from our study of IQ and African ancestry within a large sample of black adolescents that contradicts the hypothesis that IQ and race are closely correlated. All of the children in our study were socially classified as black but differed individually in their proportion of African ancestry. We found no relationship between blood group and serum protein markers of African ancestry and cognitive test scores. If more African ancestry is not related to lower scores among socially-classified blacks, then African ancestry can hardly be an explanation for IQ differences between black and white groups. The authors also fail to address evidence for lower heritability of IQ scores within a large sample of black identical and fraternal twins, which suggests that environments are less equally distributed among blacks than among whites.

Let’s take a look at the money portion of that quote again:

We found no relationship between blood group and serum protein markers of African ancestry and cognitive test scores.

Whoops, that sounds like another nail in the coffin for the “genetic” team.

[NojNoj]

@Evil_Economist

Whoops, that sounds like another nail in the coffin for the “genetic” team.

I’m surprised to read all this back and forth over issues that seem like they’ve been decided. How can anyone question that a portion of intelligence is genetically inherited? (Besides being demonstrated in a lot of studies, it’s just common sense. Why would that one aspect of human beings be immune from genetics, while height, hair color, muscle composition, propensity to mental illness, etc. etc. etc. always have a genetic component?)

And if you accept evolution, then you have to accept the likelihood that groups of people with similar genetic heritage are going to vary in terms of their genetic component of intelligence. And it need not be natural selection–there are things like founders’ effects that could lead to variations (I think some people call this "synthetic evolution.) So, just by way of example, the first six families that decide to go strike out and settle in Asia just might happened to have been above-average in intelligence. Then, everyone related to them, ends up, on average, being above-average in intelligence.

Do any of the fervent anti-racists (I assume that’s how they see themselves) dispute that aspect of evolution?

[Evil_Economist]

@NojNoj

I’m surprised to read all this back and forth over issues that seem like they’ve been decided. How can anyone question that a portion of intelligence is genetically inherited? (Besides being demonstrated in a lot of studies, it’s just common sense. Why would that one aspect of human beings be immune from genetics, while height, hair color, muscle composition, propensity to mental illness, etc. etc. etc. always have a genetic component?)

And if you accept evolution, then you have to accept the likelihood that groups of people with similar genetic heritage are going to vary in terms of their genetic component of intelligence. And it need not be natural selection–there are things like founders’ effects that could lead to variations (I think some people call this "synthetic evolution.) So, just by way of example, the first six families that decide to go strike out and settle in Asia just might happened to have been above-average in intelligence. Then, everyone related to them, ends up, on average, being above-average in intelligence.

Do any of the fervent anti-racists (I assume that’s how they see themselves) dispute that aspect of evolution?

Yeah, you missed the point.

Let’s look at your post here:

you have to accept the likelihood that groups of people with similar genetic heritage are going to vary in terms of their genetic component of intelligence

OK, fine. Now, here’s the money question: Do all people with black skin have “similar genetic heritage”?

[NojNoj]

@Evil_Economist

Do all people with black skin have “similar genetic heritage”?

Of course not, but people with West-African genetic heritage do, just like people of South-Asian genetic heritage do, etc.

(And then you get to the whole issue of genetic clustering and Lewontin’s fallacy: Human Genetic Diversity: Lewontin's Fallacy - Wikipedia)

[Evil_Economist]

@NojNoj

Of course not, but people with West-African genetic heritage do, just like people of South-Asian genetic heritage do, etc.

OK, so you accept that there are people with black skin who have different genetic heritages than other people who also have black skin?

[NojNoj]

@Evil_Economist

OK, so you accept that there are people with black skin who have different genetic heritages than other people who also have black skin?

Again, of course. I’m more familiar with these sorts of arguments when it comes to running ability. I think the conclusion there is that people of West African descent are more different than East Africans than European whites are from either group (and this shows up in World Record results: West Africans are best adapted for sprinting, European Whites for Middle Distances, and East-Africans for Distance).

I’m just arguing that in the name of “equality” you don’t become a “liberal creationist” and deny either the results of well-designed studies or basic tenets of evolution. (And I don’t have the data in front of me, but in all the things I’ve read, one thing that’s clear is that Asians clearly outperform everyone else on whatever it is that intelligence tests measure. This held true most strikingly in a study of South Asian orphans, some significant percentage of who had to be hospitalized for malnutrition, but then later outperformed European whites in intelligence tests.)

[Evil_Economist]

@NojNoj

Again, of course.

Excellent, so if people with black skin have different genetic backgrounds, then the argument that:

groups of people with similar genetic heritage are going to vary in terms of their genetic component of intelligence

simply cannot be applied to people with black skin, correct?

That is, we would not expect “people with black skin” to “vary in terms of their genetic component of intelligence” because people with black skin do not form a group of “people with similar genetic heritage.”

Welcome to the club; you are now an “anti-racist”.

[NojNoj]

@Evil_Economist

Welcome to the club; you are now an “anti-racist”.

"

Sure, but I’m actually open to the idea that “African-Americans” share a unique genetic heritage, even if there has been some miscegenation.

[bldysabba]

@NojNoj

I’m surprised to read all this back and forth over issues that seem like they’ve been decided. How can anyone question that a portion of intelligence is genetically inherited? (Besides being demonstrated in a lot of studies, it’s just common sense. Why would that one aspect of human beings be immune from genetics, while height, hair color, muscle composition, propensity to mental illness, etc. etc. etc. always have a genetic component?)

And if you accept evolution, then you have to accept the likelihood that groups of people with similar genetic heritage are going to vary in terms of their genetic component of intelligence. And it need not be natural selection–there are things like founders’ effects that could lead to variations (I think some people call this "synthetic evolution.) So, just by way of example, the first six families that decide to go strike out and settle in Asia just might happened to have been above-average in intelligence. Then, everyone related to them, ends up, on average, being above-average in intelligence.

Do any of the fervent anti-racists (I assume that’s how they see themselves) dispute that aspect of evolution?

I agree it’s quite ridiculous to deny that intelligence has a genetic component to it. So ridiculous in fact, that I doubt anyone here is saying that. My guess is that they’re merely stating that there’s no evidence this genetic component varies significantly across races. Or that races exist in the first place. That’s the usual argument in these threads

[Evil_Economist]

@NojNoj

"

Sure, but I’m actually open to the idea that “African-Americans” share a unique genetic heritage, even if there has been some miscegenation.

So, you now think that all American people with black skin “share a common genetic heritage”?

[NojNoj]

@bldysabba

My guess is that they’re merely stating that there’s no evidence this genetic component varies significantly across races.

But why wouldn’t it? There’s variation in every other genetic component of what goes into making humans, human. (And like it or not, there is clustering of genetic markers in people who share a geographical origin; again, as you’d expect from principles of evolution.)

[NojNoj]

@Evil_Economist

So, you now think that all American people with black skin “share a common genetic heritage”?

To be more precise, all Americans descended from slaves share some genetic heritage.

[Evil_Economist]

@NojNoj

To be more precise, all Americans descended from slaves share some genetic heritage.

Is that a) 100% of Americans with black skin, b) 0% of Americans with black skin, or c) 23% of Americans with black skin?

[NojNoj]

@Evil_Economist

Is that a) 100% of Americans with black skin, b) 0% of Americans with black skin, or c) 23% of Americans with black skin?

Gee, I misplaced the study I did on that…

But my sense is that most Americans with black skin color are descended from West Africans who survived forced transport in slave ships and then were able to survive generations of slavery.