1. Race as a biological-genetic reality?

Before one can examine whether there are race group differences in intelligence (IQ, 'g'), it is necessary to ascertain whether there is a biological-genetic reality to race. If there is a biological-genetic reality to race, then there is a basis for attributing group differences to race. If not, then observed group differences on any factor under study cannot be described as race differences. The reasons for the discrepancy must be found in other explanations.

The short of it is that race, as we usually understand it, is a socio-political convention that has no basis in biological-genetic reality. It is a concept of classification that has utility for social and political purposes. Here is a quote from a paper, "Confusions About Human Races", by R. C. Lewontin:

"The every-day socially defined geographical races do identify groups of populations that are somewhat more closely similar to each other genetically. Most important from the standpoint of the biological meaning of these racial categories, however, most human genetic variation does not show such "race" clustering." -R.C. Lewontin is Alexander Agassiz Professor Emeritus of Zoology at Harvard University. He has written a number of books and articles on evolution and human variation, including Biology as Ideology: The Doctrine of DNA and The Triple Helix: Gene, Organism, and Environment.

Most of human genetic variation of all kinds, 85 percent, is observed in the immense differences among individuals. Most of those differences are found within local national and linguistic groups. As for the remaining 15 percent, it is split between differences between local national and linguistic groups (French vs Ukrainians), and the socio-political groupings. On top of this is the imprecision of categorizing people into the 'classical' race groups. Keep in mind that we are talking about all types of variation, not just IQ. Lewontin has argued, with plenty of data, that race is only skin deep.

2. Individual differences versus group differences

We have to distinguish between individual differences and group differences, especially when it comes to IQ. There is more than ample evidence to support a genetic component to differences among individuals on measured IQ. There are probably a number of factors that make up measured IQ, and there are probably a number of genes that contribute to these differences.

The problem arises when evidence of a genetic basis for individual differences is used to support claims of a genetic basis for group differences. This fundamental mistake is manifest even to this very moment in the discussion, here, on this issue. To most people, the argument seems plausible, if not downright obvious. The erroneous logic goes like this: Since genes influence IQ differences among individuals, then group differences on IQ must also have a genetic foundation. Nothing could be father from the truth.

The only way we could observe genetically based group differences of any kind, is if a group was able to breed in isolation, or relative isolation, for a long period of time. There is some evidence that Jews among the Ashkenazim, may have a higher IQ than other groups. If there is a genetic basis to this difference, it would have to be based on breeding in isolation (from members of other groups). This is a plausible explanation, though I am not familiar with the data. The West African peoples who became forced chattel in the Atlantic slave trade since the fifteenth century CE were hardly breeding in isolation, before or since.

As genetic research advances it will be possible to classify people based a DNA profile. But as you noted these genetic groups will NOT line up to what is commonly defined as race. e.g. Two people in the same genetic group may look very different while two people that look very similar will be in different genetic groups.

These genetic groups will have very positive impacts in medicine. Medical treatments, diets, who is prown to specific illnesses and thus should get diagnostic test, and when they should will all be impacted by these genetic advancements.

What value the social sciences will get is unclear but if we can get away from the current overly broad race classifications that would be progress.

1. There are readily identifiable clusters of points, corresponding to traditional continental ethnic groups: Europeans, Africans, Asians, Native Americans, etc. (See, for example, Risch et al., Am. J. Hum. Genet. 76:268–275, 2005.)

2. This clustering is a natural consequence of geographical isolation, inheritance and natural selection operating over the last 50k years since humans left Africa.

3. Two groups that form distinct clusters are likely to exhibit different frequency distributions over various genes, leading to potential group differences. See comment by Hsu on the Risch paper - <link>

4. In terms of the Lewontin quote, note the Lewontin fallacy discussed here by Steve Hsu:

"Further technical comment: you may have read the misleading statistic, spread by the intellectually dishonest Lewontin, that 85% percent of all human genetic variation occurs within groups and only 15% between groups. The statistic is true, but what is often falsely claimed is that this breakup of variances (larger within group than between group) prevents any meaningful genetic classification of populations. This false conclusion neglects the correlations in the genetic data that are revealed in a cluster analysis. See here for a simple example which shows that there can be dramatic group differences in phenotypes even if every version of every gene is found in two groups -- as long as the frequency or probability distributions are distinct. Sadly, understanding this point requires just enough mathematical ability that it has eluded all but a small number of experts.) Update: see here for an explanation in pictures of Lewontin's fallacy. I also edited the paragraph above for clarity.

On the other hand, for most phenotypes (examples: height or IQ, which are both fairly heritable, except in cases of extreme environmental deprivation), there is significant overlap between different population distributions. That is, Swedes might be taller than Vietnamese on average, but the range of heights within each group is larger than the difference in the averages. Nevertheless, at the tails of the distribution one would find very large discrepancies: for example the percentage of the Swedish population that is over 2 meters tall (6"7) might be 5 or 10 times as large as the percentage of the Vietnamese population. If two groups differed by, say, 10 points in average IQ (2/3 of a standard deviation), the respective distributions would overlap quite a bit (more in-group than between-group variation), but the fraction of people with IQ above some threshold (e.g., >140) would be radically different. It has been claimed that 20% of all Americans with IQ > 140 are Jewish, even though Jews comprise only 3% of the total population."

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Since you have a lot of useful infomation on this topic, if 'race' is to be used to study people to determine how intelligent they are, if you were doing such a study on Americans, how many groups (categories) of race would you have? I see that you reference 'Europeans, Africans, Asians, Native Americans etc..', but these are not really races but geographic areas of the world. Yes as you noted these are highly correlated with the number of 'races' most lay people are use to (whites, blacks, Asians (but really east Asians), but would latino be a group in your study (or are they white), would American's from India be Asians, etc...

Again, I really thank you for all the links you have provided the last few days. Very interesting stuff, but I still wonder how you would recommend such a study be conducted on a population of Americans. Also, I'm a half breed (half Asian \ White), would I be kicked out of the study (i.e. note enough in my category to measure?)

Good questions. The person to ask is Dr Neil Risch at Stanford. He discusses the genetic differentiation US racial groups in the paper below in relation to biomedical research. The link below has a very detailed and interesting discussion of these issues. In terms of people of mixed ancestry, he writes:

"Although the US Census results suggest the large majority of individuals can be categorized into a single ancestral group, there remain individuals of mixed ancestry who will not be easily categorized by any simple system of finite, discrete categories. On the other hand, such individuals can be particularly informative in epidemiologic studies focused on differentiating genetic versus environmental sources for racial/ethnic difference."

He notes here that Hispanic is a particularly complex group:

"The most complex group is made up of those who self-identify as Hispanic/Latino. The US Census did not consider this group as a separate race, although 42% of respondents who considered themselves Hispanic checked the category 'other race' for the racial question, while 48% checked 'White'. Hispanics are typically a mix of Native American, Caucasian and African/African American, with the relative proportions varying regionally. Southwest Hispanics, who are primarily Mexican-American, appear to be largely Caucasian and Native American; recent admixture estimates are 39% Native American, 58% Caucasian and 3% African [24]. By contrast, East Coast Hispanics are largely Caribbean in origin, and have a greater proportion African admixture [25]. Thus, depending on geography, self-identified Hispanics could aggregate genetically with Caucasians, Native Americans, African Americans or form their own cluster."

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Ben017, you wrote in a previous post:

"The Blacks ended up with lower IQs than their adoptive families and the Asians ended up with IQs higher than their adoptive families."

You said this was evidence of a genetic, rather then cultural, explanation for IQ differences.

Your logic here is very weak.

If I look Asian, I will be treated as Asian by my peers, and am more likely to associate with Asians. If I look black, the same logic applies.

One's culture is one's peer group. Asians feel under enormous pressure to succeed in tests, as demonstrated by the very high suicide rates among Chinese and Japanese students.

As a result, they will work harder and faster in standardised tests than cultural groups who do not feel the same expectations and pressures.

Secondly - if there was a convincing genetic case for low black intelligence, you would expect African-Americans - who have widely interbred with other races - to outperform pure-bred Africans academically. Instead, the reverse is true, not only in the US but in other countries with black minorities. There is no way you can "cluster" your way out of that one.

"I will be treated as Asian by my peers"

You're forgetting this: Sandra Scarr, after conducting the Minnesota Transracial Adoption Study: "Within the range of 'humane environments,'variations in family socioeconomic characteristics and in child-rearing practices have little or no effect on IQ measured in adolescence." P. 476

"There is simply no good evidence that social environmental factors have a large effect on IQ, particularly in adolescence and beyond, except in cases of extreme environmental deprivation." P. 476

By adulthood, all of the IQ correlation between biologically related persons is genetic. P. 178 Phenotypic g closely reflects the genetic g, but bears hardly any resemblance to the (shared) environmental g. P. 187 From Jensen, A. R. (1998). The g factor: The science of mental ability. Westport, CT: Praeger:

The B-W gap can be measured at age 2-1/2, so your explanation of culture seems unlikely. [see Rushton, J.P. and Jensen, A.R. (2005). Thirty Years of Research on Race Differences in Cognitive Ability. Psychology, Public Policy, and Law, Vol. 11, No. 2, 235-294.] [also see Jensen, A. R. (1998). The g factor: The science of mental ability. Westport, CT: Praeger.]

European blacks have the same mean IQ as US blacks. Blacks in sub-Saharan Africa have a mean IQ of 67. In that region, the economy is dominated by Indians who were brought in during Colonial times as workers. Indians built most of the buildings that stand in East Africa. In Brazil, blacks have a mean IQ of 71; those of mixed ancestry have a mean of 81. The highest mean income in Brazil is by Japanese, followed by Europeans, Mulattos, and Blacks. IQs by nation are reported in Lynn, Richard (2006). Race Differences in Intelligence: An Evolutionary Analysis. Social standing by race is reported in The Global Bell Curve (2008) by Lynn.

Wow, you can prove anything with JSTOR. I discovered that during my masters programme.

All you need to do is cite selectively. I could do exactly what you just did, in reverse - or I could just link to someone else who's already done it.

Yeah, I posted that. So, do you actually have any arguments? What are you disputing:

1. That psychometrics can measure 'g' or a general intelligence factor?

2. That this is largely hereditary?

3. That this may vary in distribution between groups?

1. Psychometrics. IQ tests test several things, in the following order of importance:

a) How motivated are you to do the test? Will you race through the questions as fast as you can, or adopt a leisurely approach?
b) Do you know the tricks? A great many IQ questions require foreknowledge of a simple trick to solve them. Practice yields the tricks. So does cultural context e.g practice understanding spatial awareness.
c) The "speed limit" on your brain. If two candidates are equally motivated, and know the relevant tricks, who can do it faster? This is as close as an IQ test comes to measuring intelligence.

2. Largely hereditary. A friend of mine is an insomniac. He is a bundle of energy, a trait that I think he inherited from his mother. He is also clever, with a first class degree from Oriel, Oxford.

How do these traits apply to a), b) and c)? Well, his parents were always keen for him to do well and paid for him to go to boarding school. They manipulated his environment in such a way that he came to view test scores as extremely important. His expensive school also taught him the techniques necessary to perform well in both class essays and written exams.

He also is a tightly wound bundle of energy, and tends to work hard for that reason. So I suppose you could say that is heritable.

But as for c), it's a little hard to say, given the other variables at play.

3. Group distribution. Who knows? The only thing approximating to intelligence that is measure by tests is c), and it represents a small part of the results. Assuming a c) variable exists, it is likely to be influenced by such things as diet and temporary environmental factors. My brain seems to run quicker some days than it does others.

By the way, you say that in east Africa the economy is dominated by Indians. That's partly true of, say, Kenya. It's not at all true of the richer-per-capita Botswana. Though according to Lynn, who seems to share you views, the average IQ in India is a pitiful 81, well below heavily black countries like Brazil, Colombia, and Cuba.

"Though according to Lynn, who seems to share you views, the average IQ in India is a pitiful 81, well below heavily black countries like Brazil, Colombia, and Cuba."

India is an interesting case, as those who migrate to places like the US invariably end up averaging about the same, if not higher, than whites. Richwhine reported on this here:

"The only direct evidence we have comes from the 2003 New Immigrant Survey, in which a basic cognitive test called "digit span" was administered to a sample of newly arrived immigrant children. It is an excellent test for comparing people with disparate language and educational backgrounds, since the test taker need only repeat lengthening sequences of digits read by the examiner. Repeating the digits forward is simply a test of short-term memory, but repeating them backward is much more mentally taxing, hence a rough measure of intelligence.

When statistical adjustments are used to convert the backward digit span results to full-scale IQ scores, Indian Americans place at about 112 on a bell-shaped IQ distribution, with white Americans at 100. 112 is the 79th percentile of the white distribution. For more context, consider that Ashkenazi Jews are a famously intelligent ethnic group, and their mean IQ is somewhere around 110.

Given the small sample size, the rough IQ measure and the lack of corroborating data sets, this finding of lofty Indian-American intelligence must be taken cautiously. Nevertheless, it is entirely consistent with their observed achievement."

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"Psychometrics. IQ tests test several things, in the following order of importance:"

The thing is that the tests have external validity in terms of the general intelligence factor 'g' which is obtained from factor analysis. Interestingly, Elementary Cognitive Tasks (chronometric measures) can measure g as well as good IQ tests.Today, virtually all intelligence research (worldwide) is about g. That is, they must give the test to many people and then use factor analysis to compute g for the test. They can compute g loading for individual items. If they want to know g for an individual, they usually give a heavily g loaded test and take the result as a good indicator. In the case of the Raven's tests, they usually assume that the result is g.

This is amazingly robust at predicting group characteristics. It is not deterministic in many aspects at the individual level. For instance, a high IQ does not mean that you will have a lot of education, but if you have a large representative sample of people with high IQs they will have a lot of education.

I noted above some of the neurological correlates in terms of myelination, cortical thickness, and the development rates in the cortex in more gifted children. For a summary and discussion of this see this paper by Thompson & Gray. www.loni.ucla.edu/~thompson/PD­F/nrn0604-GrayThompson.pdf

Reaction time is one of the simplest culture-free measures. Many RT tasks are so easy that 9- to 12-year-old children can perform them in less than one second. Yet even on these very simple tests, children with higher IQ scores perform faster than do children with lower scores. Since school children are not trained to perform well on reaction time tasks, as they are on certain paper-and-pencil tests, the advantage of those with higher IQ scores on these tasks is unlikely to arise from practice, familiarity, education, or training. On average there is a consistent three-way race difference has been found on reaction time tasks in over 400 9- to 12-year-olds with East Asians faster than Whites, and Whites faster than Blacks. The hypothesis that the group differences on these tests reflect a difference in motivation is disconfirmed by the fact that although the East Asians averaged faster reaction times (that is, quicker mental decision making) than the Whites or the Blacks, the Blacks averaged faster movement times (the actual motor response) than the Whites or East Asians.

Rushton, J. P., & Jensen, A. R. (2009). Race and IQ: A Theory-Based Review of the Research in Richard Nisbett’s Intelligence and How to Get It. Working paper, Department of Psychology, University of Western Ontario, London, Canada.

I suppose my point is that whatever is measured by these tests, it is not innate and can be coached. This coachability is the crucial point - did you see this piece in the NYT?

Unfortunately, that piece in the NY Times is based on Nisbett's book, which is a work of politically correct advocacy. Here is a 40 page review by Jensen & Rushton which you can guarantee the NY Times will not be mentioning:

Rushton, J. P., & Jensen, A. R. (2009). Race and IQ: A Theory-Based Review of the Research in Richard Nisbett’s Intelligence and How to Get It. Working paper, Department of Psychology, University of Western Ontario, London, Canada. <link>

Just looking at the Times article it mentions the work of Turkheimer & a French adoption study. There is a discussion of the French study here. <link>

In terms of Turkheimer's study, note:

1 - The study included only young children and does not make any attempt to extrapolate that all other findings of significant increases in h^2 by age 17 are in any way invalid. The effects of the shared environment vanish at around age 12.

2 - Turkheimer began his paper by recognizing that the heritability of cognitive ability in childhood is well established.

3 - Turkheimer made no attempt whatsoever to determine what components of SES he was measuring. There are three obvious items to consider: macro environmental, micro environmental, and genetic. All work to date indicates that the first of these can be found in children, but that it is absent in late adolescents; by late adolescence, all of the environmental component is of the second type; and that genetic intelligence is the largest determinant of SES.

4 - Turkheimer says that the effect he observed was related to the homes in which the children were raised. This is interesting, since it relates to the adoption studies which show that after childhood there is no adult IQ correlation between biologically unrelated children who were reared together in the same home.

5 - Turkheimer discusses in some detail that SES is not strictly an environmental variable, since it is known to be (statistically) caused by the intelligence of the parents. He points out that the models he used "cannot determine which aspect of SES is responsible for the interactions" observed.