Small Between-Group Variance Doesn't Settle What That Variance Contains

2026-07-31 · AI-generated insight

Place Lewontin beside Warne and you get a clean collision — but not the one either author stages. Lewontin's argument is statistical: the vast majority of human genetic variation lives within populations, only a sliver between them, therefore racial classification is taxonomically empty. Warne's argument is causal: whatever the size of between-group differences in one specific trait, part of it may be genetic in origin.

The tension is instructive precisely because these claims are not logical opposites. A partition of variance tells you how much difference sits between groups; it tells you nothing about what that difference does or whether it maps onto any trait we care about. This is the crux of Edwards' famous rejoinder to Lewontin — that classification accuracy can be high even when any single locus is uninformative, because information accumulates across loci. Small between-group variance and non-zero between-group causation can both be true. Lewontin's number does not do the refuting work it's usually enlisted for.

But notice how much Warne concedes in the same breath, and how that concession echoes Lewontin's real point. His claim is hedged to native English speakers born in the US, restricted to one trait, and explicitly declared 'not fully conclusive.' That is a long way from the robust, cross-context kinds that racial taxonomy presupposes. Lewontin's deepest charge wasn't that between-group variance is literally zero — it's that the categories don't carve nature at meaningful joints. Warne, by narrowing his populations to a single national, linguistic, historically-specific slice, is quietly agreeing: the boundaries only mean something once you've done enormous work fixing the context.

So the honest synthesis is uncomfortable for both filing systems. 'The Biological Reality of Race' holds both notes, yet each undermines the other's strongest form. Lewontin overreaches when the variance partition is treated as a proof of nothing-there. Warne overreaches if a fragile, context-bound estimate is read as vindicating the folk category. What survives is narrow and awkward: statistically real, causally uncertain, and taxonomically far weaker than the word 'race' implies.

Woven from these notes

It is clear that our perception of relatively large differences between human races and subgroups, as compared to the variation within these groups, is indeed a biased perception and that, based on randomly chosen genetic differences, human races and populations are remarkably similar to each other, with the largest part by far of human variation being accounted for by the differences between individuals. Human racial classification is of no social value and is positively destructive of social and human relations. Since such racial classification is now seen to be of virtually no genetic or taxonomic significance either, no justification can be offered for its

— Lewontin 2026-07-20

The past 30 years of research in intelligence has produced a wealth of knowledge about the causes and consequences of differences in intelligence between individuals, and today mainstream opinion is that individual differences in intelligence are caused by both genetic and environmental influences. Much more contentious is the discussion over the cause of mean intelligence differences between racial or ethnic groups. In contrast to the general consensus that interindividual differences are both genetic and environmental in origin, some claim that mean intelligence differences between racial groups are completely environmental in origin, whereas others postulate a mix of genetic and environmental causes. In this article I discuss 5 lines of research that provide evidence that mean differences in intelligence between racial and ethnic groups are partially genetic. These lines of evidence are findings in support of Spearman’s hypothesis, consistent results from tests of measurement invariance across American racial groups, the mathematical relationship that exists for between-group and within-group sources of heritability, genomic data derived from genome-wide association studies of intelligence and polygenic scores applied to diverse samples, and admixture studies. I also discuss future potential lines of evidence regarding the causes of average group differences across racial groups. However, the data are not fully conclusive, and the exact degree to which genes influence intergroup mean differences in intelligence is not known. This discussion applies only to native English speakers born in the United States and not necessarily to any other human populations.

— Russell Warne Between-Group Mean Differences in Intelligence in the United States Are >0% Genetically Caused: Five Converging Lines of Evidence 2026-07-20