“But honestly I’d rather the debate center on the students’ discussion of performance enhancing drugs.”

Fair enough, I’ve never actually tried any although if I had my time over I might consider it.

There is a fantastic article here by Johan Hari about his experiment with smart drugs & why he stopped taking them.

http://www.johannhari.com/archive/article.php?id=1298

Thanks for the link, here is a discussion by JP Roos in relation to inequality generally which cites that edition of Psychology, Public Policy, and Law, 11, 328-336. that edition of J. P. Rushton & Jensen, A. R (2005).

http://www.valt.helsinki.fi/staff/jproos/inequality.htm

Here is the reply to Nisbett, Sternberg & Aronson in that edition.

http://www.udel.edu/educ/gottfredson/30years/Rushton-Jensen-reply-to-commentaries-on-30years.pdf

>Race/ethnicity is also a social >category (or folk taxonomy), and >thus a serious impediment when >included in this type of research >since it doesn’t capture the >relevant variation.

It’s a social category, but groups cluster into these recognisable groups. Also, note that in terms of classic anthropology WW Howell’s analysis of cranial measurements identified seven groups which largely correspond to the population clusters Cavalli-Sforza identified.

In relation to more recent studies there is a discussion of the paper by Neil Risch here by Steve Hsu:

http://infoproc.blogspot.com/2007/01/metric-on-space-of-genomes-and.html

The problem with this is that it is from this paper by Turkheimer E
‘Socioeconomic status modifies heritability of IQ in young
children.’ Psychol Sci 2003; 14: 623–628.

A few problems with this paper:

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.

6. In Britain, the exact opposite of Turkheimer’s result was found in over 2,000 pairs of 4-year-old twins (N = 4,446 children), with greater heritability observed in high-risk environments.

7. A re-analysis of the Hawaii Family Study of Cognition also found contrary results to Turkeimer’s. Nagoshi and Johnson found no reduction in the relationship between parental cognitive ability and offspring performance in families of lower as opposed to upper levels of socioeconomic status. In the 1,349 families they studied, the relationship remained the same across tests, ethnicity, and sex of offspring.

Asbury, K., Wachs, T. D., & Plomin, R. (2005). Environmental moderators of genetic influence on verbal and nonverbal abilities in early childhood. Intelligence, 33, 643-661.

75. Nagoshi, C. T., & Johnson, R. C. (2005). Socioeconomic status does not moderate the familiality of cognitive abilities in the Hawaii Family Study of Cognition. Journal of Biosocial Science, 37, 773-781.

The Flynn Effect: Troubles with Intelligence #2

How Intelligent Are Intelligence Tests?

Neuroanthropology and Race – Getting It Straight

You should also look at the science in a more balanced way. Let me draw from a recent review on genetics and intelligence by Deary et al (pdf). Noting that the majority of genetic studies do not actively account for relevant environmental variations, the paper moves on to discuss heritability (h2) and shared environment (c2). Here is the relevant quote: “This sample [from the National Collaborative Perinatal Project] has a high proportion of impoverished families. One useful summary is an analysis in which families were dichotomized into high and low socio-economic status (SES). For high SES families, h2 was 0.71 and c2 was 0.15. For low SES families, h2 was 0.10 and c2 was 0.58 (694).”

Race/ethnicity is also a social category (or folk taxonomy), and thus a serious impediment when included in this type of research since it doesn’t capture the relevant variation. So here is Robert Sternberg et al. (2005), Intelligence, Race and Genetics (pdf) in American Psychologist: “They further argue that race is a social construction with no scientific definition. Thus, studies of the relationship between race and other constructs may serve social ends but cannot serve scientific ends. No gene has yet been conclusively linked to intelligence, so attempts to provide a compelling genetic link of race to intelligence are not feasible at this time. The authors also show that heritability, a behaviorgenetic concept, is inadequate in regard to providing such a link.”

And for those interested, here is an article by Nisbett and race & intelligence (pdf).

But honestly I’d rather the debate center on the students’ discussion of performance enhancing drugs.

“despite their lower performance, which is genuine, multiple lines of evidence point to African-Americans valuing academics nearly as much as white Americans, if not equally so (for instance spending just as much time on homework. A number of lines of evidence are discussed by Ludwig and Cook in The Black-White Test Score Gap, which you can read here). But an even more profound revelation that causes doubt about cultural explanations is that behavioral genetic experiments show us that home and parental environments don’t seem to matter at all. As fantastic as it may be, at least three big studies now show us that unrelated children raised in the same household, as well as parents and their adoptive children, differ in IQ as much as any two strangers randomly picked from the general population. There are IQ similarities in biological families, but we find that once genes are accounted for, there is no residual left to explain.

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?

Contrary to “culture” theory, the ethnic academic gaps are almost identical for transracially adopted children, and to the extent they are different they go in the opposite direction predicted by culture theory. The gap between whites and Asians fluctuated from 19 to .09 in the NAEP data while the gap in the adoption data is from 1/3 to 3 times larger. This is consistent with the Sue and Okazaki paper above which showed that contrary to popular anecdotes, the values that lead to higher academic grades are actually found more often in white homes. In other words Asian-Americans perform highly despite their Asian home cultural environment not because of it. And though the sample is meager, I find it interesting that the gap between the black and white adopted children was virtually identical (within just 4-6 points) to the gap between whites and blacks in the general population, just like in the Scarr adoption study.

http://www.gnxp.com/MT2/archives/004064.html

1. 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

2. From that study the black children adopted by white families matured to have IQs that are consistent with their biological peers; Asian children adopted by white families mature to have IQs that are consistent with their biological peers and which are higher than their adoptive parents.