Race, genes, & intelligence, part 0

This is divided into three sections:
A. Clarifications
B. The plausibility of the Hereditarian Hypothesis
C. The likelihood of socially important genetic differences between populations
D. The reasonability of positing the Hereditarian Hypothesis

A. Clarifications

Motivation

My interest is not in convincing anyone that this or that subpopulation phenotypic difference has a partial genetic etiology, but rather in forcing an empirical test of the genetic hypothesis and resolving this issue once and for all. To do that, it is necessary to demonstrate (to the public and misinformed members of academia) that this is a yet unresolved issue of pressing social importance. Levin (1997), Jensen (2000), Gottfredson (2005), Sesardic (2005), and Hunt and Carlson (2007) have laid out the case for bringing closure to the issue; those interested are left to bring the matter to public consciousness and to challenge those believers in the reigning paradigm to subject their prejudices to investigation. This issue, for the most part, can be resolved in a matter of months. With regards to the questions of evolved ancestral differences, Rowe (2005), Rushton and Jensen (2005), Murray (2005), Hunt and Carlson (2007), and Lee (2009) have already discussed the proper tests that would provide dispositive results: admixture studies. Such studies, which are now commonly done (see: Winkler et al., (2010), Admixture Mapping Comes of Age) to locate the origins of medical disparities would, if properly done, end this debate.

Clarification about the Concept of Race

On the matter of biology and race, there seems to be considerable confusion, no doubt artfully sowed. Given that, let me clarify: When it comes to the hereditarian hypothesis, we are not discussing the philosophy of biology — I discuss some aspects of that here — we are discussing the etiology of differences between socially identifiable ethnoracial groups. These groups represent different biological population structures. The assumption here is not that these ethnoraces are taxonomically identifiable groups or that there are clear boundaries between these groups, but rather that the said groups have different population structures. When the Human Genome Project states that “DNA studies do not indicate that separate classifiable subspecies (races) exist within modern human,” they are talking about biological taxonomic classifications and saying that there are no population specific genes that would warrant classifying various populations as subspecies. That is a separate issue. (See: 70-71). With regards to the current discussion, we are starting with socially identified ethnoracial groups which have different population structures and asking: “Why are there behavioral differences?”

McEvoy, et al., 2010. Whole-genome genetic diversity in a sample of Australians with deep Aboriginal ancestry

Trishkoff, 2010. The Genetic Structure and History of Africans and African Americans

Race concepts, nonetheless

Since the mantra of “race is a social construct (RISC)” is often intoned to ward of the specter of Jensenism, a little more clarification is, perhaps, needed. The “RISC” concept comes by way of Lewontin. Unlike many of our contemporaneous academic charlatans who peddle the “RISC” concept, Lewontin was kind enough to provide criteria for falsifiablity. According to Lewontin (1972), RISC means that racial classification are of “virtually no genetic or taxonomic [superfamily to subspecies] significance.” The scientific community has since rejected the notion that race, whether delineated by continental, sub-continental, or regional ancestry (lumpers and splitters), is of no such significance. [2, 17, 22, 28, 42, 44, 62, 69, 71]. (The root of “race” is “ancestry,” word games about “lactose intolerant races” notwithstanding). The RISC hypothesis has been falsified and Lewontin’s claim about race is now know as Lewontin’s fallacy.

None of the above has stopped many (every other social “scientist”) from asserting that RISC is, nonetheless, true. Often, a sleight of hand is pulled and, while the pretense that race is of “no genetic or taxonomic significance” is maintained, RISC is redefined to mean that racial classifications do not represent subspecies; some go so far as to baldly claim that “the social construction of race,” now redefined to mean the lack of consensus concerning the taxonomic status of race, contradicts the biogenetic concept of race (e.g. Smedley, 2005). (It’s worth noting that in many parts of the world,, the race concept has wide currency; see: Lieberman et al., 2004. The race concept in six regions: variation without consensus).

To emphasize again, with regards to the Hereditarian hypothesis and the question of mean differences between socially classified subpopultions, whether or not there are human subspecies and whether everyone fits neatly into some grouping is immaterial. What is presupposed is that different racial (read: regional ancestral) classifications describe, on average, sets of individuals with different (average) ancestries. See: A defense of the Race concept.

Clarification about the meaning of general intelligence

General intelligence (g) can operantly be defined as the property that both IQ and Reaction time tasks measure. A more technical definition is the “substantial covariation among diverse measures of cognitive ability as indexed by an unrotated first principalcomponent score, which typically accounts for about 40% of the total variance of diverse cognitive tests, or by a total score across diverse tests as is done in intelligence tests ” (Plomin and Spinath, 2004. Intelligence: Genetics, Genes, and Genomics).

The educational, social, and psychological, and neurophysiology correlates of g are well established; no other phenomena has been as well researched in psychology as that of general intelligence. For a good review of the empirical findings refer to Deary et al. 2010. The neuroscience of human intelligence differences. There is some debate as to whether g represents a causal entity or whether it is epiphenomenal. For a good discussion of this, refer to: Gottfredson, 2010. Intelligence and Social Inequality: Why the Biological Link?. This is an interesting question, but as differences in g are highly predictive of social outcomes, it does not matter if g represents a causal entity, if g represents a set of correlations tied to causal entities (e.g different neural functions), or if g magically recruits the environment to cause the predicted social outcomes. Differences in g matter.

Clarification about the Meaning of Average differences

When we talk about group differences, with respect to population genetics, we are talking about mean averages. Mean averages are an abstraction. They do not say anything about individual performance. (Whether or not probabilistic calculations based on these means is morally acceptable, is another issue.) As such, if you are naturally at the right tail end of some measure, you are at the right tail end.

Gottfredson, 2005. Social Consequences of Group Differences in Cognitive Ability

Clarification about the meaning of heritability

To say that a difference is heritable is to say that, given equal conditions, individuals or groups will differ as a result of genetically conditioned endogenous factors. With regards to the issue of heritability and malleability, we can quote Jensen (1973):

The proportion of variance indicated by [environmentality] , if small, does in fact mean that the source of environmental variance are skimpy under the conditions that prevailed in the population in which h^2 was estimated. It means the already existing variations in environmental conditions are not a potent source of phenotypic variance, so that making the best variations available to everyone will do little to reduce individual differences. This is not to say that yet undiscovered (or possibly already discovered but rarely used) environmental manipulation of forms of intervention .. cannot in principle markedly reduce individual differences in a trait which under ordinary conditions has very high heritability (Jensen, 1973).

Johnson, Penke, and Spinath have a nice introductory discussion on the concept of heritability. (Johnson, Penke, and Spinath, 2011. Heritability in the Era of Molecular Genetics: Some Thoughts for Understanding Genetic Influences on Behavioral). The only comment I would make is that they seem to error in this statement: “First, it is not 60% of the phenotype that is passed on to the next generation, or even 60% of genes related to deviation from the original population average in any way that has any meaning for the individual in that next generation.” They seem to suggest that heritability estimates only concern populations and are irrelevant to individuals. This is not the case, however, as individual genetic value is probabilistically related to population heritablility. For a good discussion of this, refer to Tal, 2009. From heritability to probability.