Justin’s Notes

Both Sides Can Be Reading the Genome Correctly

2026-09-04 · AI-generated insight

These two notes stage one of the sharpest disagreements in modern biology — and the interesting thing is that neither side's empirical claim contradicts the other's.

Lewontin's famous finding is about apportionment: pick a random gene, and most of its variation lies between individuals within a population, not between populations. Winegard and Carl's account is about process: geographically separated populations under different selection pressures, with gene flow blocked by oceans and mountain ranges, will gradually diverge. Both statements can be true simultaneously. Small average differences at any single locus, when correlated across thousands of loci, are enough to cluster people reliably by ancestral geography — the core of what critics later called "Lewontin's fallacy." The genome that looks homogeneous locus-by-locus can still carry a legible signature of the migration history Winegard and Carl describe.

So the real dispute isn't over the data; it's over which statistic gets to define "significance." And here Lewontin does something worth noticing: he fuses an empirical claim (races are genetically similar) with a normative one (racial classification is "positively destructive of social and human relations") in a single breath, letting each borrow authority from the other. Winegard and Carl move in the opposite direction — a scrupulously mechanistic account of drift and selection that says nothing about what any divergence means for how humans should treat one another, leaving that silence to be filled by whoever cites them.

The synthesis, then, is uncomfortable for both camps. If Lewontin's moral conclusion depends on his statistical framing, it becomes hostage to a technical dispute it may lose — a fragile foundation for anti-racism, which arguably shouldn't rest on any particular apportionment of variance. And if Winegard and Carl's evolutionary logic is sound, the burden shifts to a question their note never touches: divergence in what, of what magnitude, and with what relevance to anything we care about socially? The notes together suggest the debate is miscast — it's less about whether populations differ than about who gets to decide when a difference counts.

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

A more plausible conception of race, one that is consistent with how careful philosophers and geneticists use the term, recognises that: When humans began leaving Africa around 75,000 years ago, they dispersed across a much greater range of environments than they had previously inhabited. The humans that settled in different geographic regions subsequently came under different selection pressures (e.g. temperature, seasonality, altitude). Natural barriers such as oceans (e.g. the Atlantic), deserts (e.g. the Sahara) and mountain ranges (e.g. the Himalayas) impeded gene flow between different populations for substantial periods of time. When there is limited gene flow between populations that have come under different selection pressures, we would expect them to gradually diverge from one another over via the processes of genetic drift and natural selection.

— Bo Winegard, Noah Carl Superior: The Return of Race Science—A Review