Race, genes, and IQ test scores: The latest conceptual starter kit

The new conceptual starter kit evolved after reflection on feedback from colleagues and, when delivered two days ago to high school students, proceeded more or less as follows:

Race, Genes, and IQ test scores

Everyone has a sense that this is a controversial issue.

The title suggests a simple relationship: race is coded in genes and genes determine IQ test scores.  Or: Differences in Races => Differences in Genes that people have, which, in turn => Differences in IQ test scores

Take home lesson:

The world is not that simple.

There are lots of questions to ask and to explore.

In this talk, I want to get you to think like a scientist: Ask questions.  Put forward explanations.  Do they fit the data?  Debate alternatives.

Most of the talk is not about racial data—we’ll get to that near the very end.

————–

I won’t tell you yet what groups 1 and 2 are, but you would know if you were in them.

Notice that the average of group 2 is quite a bit higher than that for group 1.

OK. What would you make of these patterns if you were in group 1? In group 2?

[Responses from the audience.]

You might have said, it depends on where you are in group 1 or in group 2.  Near the middle?  Near the bottom end?  Near the top?

First lesson: Individuals in groups differ from the group average and should not be treated as if the group average is what they are.

Second lesson: Science is more than getting at causes.  Already, you [in the audience responses] were talking about what you would do and what more you would want to know (e.g., is the IQ test biased towards group 1?)

————–

What would you do on the basis of these patterns?

Example: Group 1 community leader: Push for better schools…  Get depressed because Group 2 will stay ahead…

What more would you want to know about these patterns before you decided what to do?

Example: IQ researcher: Work with geneticist to look for genes that group 2 have that group 1 doesn’t…

————–

Imagine you are…. (see your card to find out who [community leader in group 1community leader in group 2Teacher of children from both groupsgovernment policy-makerGenetics researcherIQ researcher]):

How would you react to these patterns in IQ test scores?

Question: What would you do on the basis of these patterns?

OR Question: What more would you want to know about these patterns before you decided what to do?

————–

[Discussion between neighbors, then sharing of responses]

What would you do on the basis of these patterns?

Examples:

Group 1 community leader: Push for better schools…  Get depressed because Group 2 will stay ahead…  Create different tests…

Government policy-maker: Accept income inequality because it comes from IQ inequality…

Teacher: Make more effort to teach people in group 1…

What more would you want to know about these patterns before you decided what to do?

Examples:

Government policy-maker: Look for situations in which group 1 and group 2 are more equal and learn from that…

IQ researcher: Work with geneticist to look for genes that group 2 have that group 1 doesn’t….

————–

IQ researcher: Work with geneticist to look for genes that group 2 have that group 1 doesn’t…

Why ask this?

Reasoning might be:

Because there is variation within each group and genes are involved in variation of other traits, e.g., height.

And the gap has been there for a while and hasn’t changed.

And there is no simple environmental or social factor that explains the gap.

And what are the alternatives?

————–

But consider results of a study from France:

New information:

Group 1 = people who were adopted by poor families.

Group 2 = their brothers and sisters who were adopted by well-off families.

Now

IQ researcher: Work with geneticist to look for social conditions that group 2 have that group 1 doesn’t.

But that is too simple.  Indeed, saying it’s a combination of genes and environment is too simple.

————–

Consider results that are common across many industrialized countries:

New information:

Group 1 is your grandparents’ generation.

Group 2 is your parents’ generation.

What would you NOW do on the basis of these patterns?

OR What more would you NOW want to know about these patterns before you decided what to do?

It turns out there is no simple environmental or social factor that explains the increase.

Would we look for genes to explain this increase?

Reasoning might be:

Because there is variation within each group and genes are involved in variation of other traits, e.g., height.

And the gap has been there in many countries.

And there is no simple environmental or social factor that explains the increase.

But we know that genes don’t change much from one generation to the next, so there must be something wrong in the logic.

We need to think about more dynamic explanations.

[Here I used Dickens and Flynn’s story about basketball in the age of TV to convey a model in which there is a matching of environments to differences that may initially be small (e.g., children who show an earlier interest in reading will be more likely to be given books and receive encouragement for their reading and book learning), and a social multiplier through which society’s average level for the attribute in question influences the environment of the individual (e.g., if people grow up and are educated with others who, on average, have higher IQ test scores, this will stimulate their own development).]

We now have a sense that genes versus environment—nature vs. nurture—is too simple and that we need more dynamic explanations, so…

————–

New information:

Group 1 are African-Americans in the USA.

Group 2 are Euro-Americans (“whites”) in the USA.

What would you NOW do on the basis of these patterns?

OR What more would you NOW want to know about these patterns before you decided what to do?

————–

Why propose that maybe genes could explain the differences in averages between the two groups.

We have seen that

Differences in Generations -> Differences in Genes -> Differences in IQ test scores

so

Is this still plausible to you? : Differences in Races -> Differences in Genes -> Differences in IQ test scores.  If so, why? (Are therefactors influencing your thinking beyond the data?)

————–

Take home lessons:

The world is not a simple matter of genes explaining anything and everything.

Be skeptical of anyone who wants you to think it could be simple.  (They are not being true to the science of average group differences.)

Ask questions—dig deeper into the complexity.

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2 thoughts on “Race, genes, and IQ test scores: The latest conceptual starter kit

  1. Chuckwiththehippo

    While, overall, this is a good introduction to the matter, your presentation is clearly biased by your interpretation of heritability. And your suggestion of interpretive bias, when it comes to the nature of group differences, is unwarranted. Note two points you make:

    1. But we know that genes don’t change much from one generation to the next, so there must be something wrong in the logic.

    Since heritability studies are based on differences between individuals of the same cohort and not individuals between cohorts (i.e there are no non-synchronous twin pairs), heritability estimates can not be generalized to non-synchronous populations. As you can’t generalize heritability from synchronous populations to non-synchronous populations, you can’t logically argue that large, presumably environmentally induced, changes between individual within non-synchronous populations undermines heritability estimates within synchronous populations. You are limited to pointing out the curiosity of the secular rises in IQ and suggesting an alternative interpretation to the between individual difference.

    Now we can derive the same conclusion through an alternative path: There is little evidence of a generational rise in general intelligence in the US; and there is plenty of evidence to the contrary (negative correlation with g-loadedness, lack of rise across the positive manifold, no endophenotypic Flynn effect). As such, we can infer that the nature of cross cohort differences is different from that of individual differences. The former does not represent g differences; the latter does. This conclusion is corroborated by MCFA, which show that the between cohort difference is not measurement invariant while the between individual difference is.

    So, by two independent lines of reasoning, we are led to the same conclusion: the between cohort differences say nothing about the between individual differences. If you are aware of some flaw in the reasonings that lead to this conclusion, I’d be happy to hear it. If not, “so there must be something wrong in the logic” is unwarranted. At very least, you should conclude this sentence with a question mark.

    2. Differences in Races -> Differences in Genes -> Differences in IQ test scores — is this still plausible to you? If so, why? (Are therefactors influencing your thinking beyond the data?)

    Since you wish to give your students a conceptual starter kit for thinking about heritable differences, it should include some information on the alternative interpretation to heritability that you are suggesting — which of course, would suggest the reason. The alternative interpretations (norms of reaction or gene-environment correlations), implies genetic differences. To me, the above point is misleading — but at least you phrased it as a question and not an authoritative statement of fact.

    Reply
  2. Chuck

    “Is this still plausible to you? : Differences in Races -> Differences in Genes -> Differences in IQ test scores. If so, why? (Are therefactors influencing your thinking beyond the data?)”

    Jensen has an article in press in which he discusses the Flynn effect and subpopulation differences. (Jensen, 2011. The theory of intelligence and its measurement). If you read it along with Must et al, 2009 (Comparability of IQ scores over time), you’ll see why the Flynn effect does not preclude an additive genetic (i.e. hereditarian) basis for individual or group differences.

    Reply

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