Abstract

The role of genetics in determining measured differences in mean IQ between putative racial groups has been a focus of intense discussion and disagreement for more than 50 years. While the last several decades of research have definitively demonstrated that genetic variation can influence measures of cognitive function, the inferences drawn by some participants in the controversy regarding the implications of these findings for racial differences in cognitive ability are highly dubious. Of equal importance, there is no compelling scientific rationale for focusing on and devoting substantial effort to determining mean differences in intelligence or other cognitive functions between groups with incompletely defined and dynamic (and therefore not definitively definable) boundaries.

Highlights

  • Professor Lewontin happened to have a strong interest in the complexities that characterize genotype–phenotype relationships [e.g., see [6] for a relatively non-technical and accessible account of this topic] and how these relationships are captured by heritability, which makes sense because one of the two technical definitions of the term, so-called narrow-sense heritability, is relevant to evolution and to practical applications of selection for traits in plants and animals that are of economic value in agriculture

  • Related to the preceding point, accepting a role, even an important role, for genetic variation in influencing variation in intelligence and other cognitive capacities or behaviors in no way necessitates concluding that individuals with what are defined as lesser apparent capabilities cannot be helped by changes in environmental factors

  • There is no compelling scientific reason to study the mean values for measures of cognitive or behavioral phenotypes associated with putative racial groups because individuals should be evaluated as individuals

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Summary

Introduction

Professor Lewontin happened to have a strong interest in the complexities that characterize genotype–phenotype relationships [e.g., see [6] for a relatively non-technical and accessible account of this topic] and how these relationships are captured by heritability, which makes sense because one of the two technical definitions of the term, so-called narrow-sense heritability, is relevant to evolution and to practical applications of selection for traits in plants and animals that are of economic value in agriculture In his course on population and evolutionary genetics, he devoted a significant amount of time and effort to exploring the subtleties of heritability with his students.

Examples of How Heritability Is Misunderstood
What Is Heritability?
Genetic Fundamentals
Genotype-Phenotype Correlations Mediated Indirectly
The Distribution of Human Genetic Variation
Conclusions
Findings
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