Science Quote by Peter R. Grant

“Evidence of epistasis from hybridization studies is more scarce” is the kind of quietly corrective sentence that signals a scientist policing the boundaries between what we suspect and what we can actually show. Peter R. Grant isn’t denying epistasis - the interaction effects between genes - he’s flagging how hard it is to catch it in the wild using one of evolutionary biology’s most seductive tools: hybridization.

Hybridization studies feel like they should be a smoking gun. Cross two populations, watch what breaks (or unexpectedly works), and you can infer genetic incompatibilities, hidden architectures, even the mechanics of speciation. The subtext of Grant’s caution is methodological: hybrids are messy data. You’re observing phenotypes produced by novel gene combinations, in unfamiliar environments, often across small sample sizes, with confounding factors like maternal effects, linkage, and selection acting immediately. Epistasis can be there and still fail to announce itself cleanly because its signature isn’t a single trait changing, but patterns of non-additivity that require dense genetic mapping, replication, and careful controls.

Context matters, too. Coming from Grant - whose work on Darwin’s finches made evolutionary change feel tangible and measurable - this scarcity line reads like a pushback against overconfident storytelling. Evolutionary genetics has a habit of turning “plausible mechanism” into “settled mechanism” when the narrative is elegant. Grant’s intent is to keep the field honest: the architecture we theorize is often richer than the evidence hybrid crosses can reliably deliver, and scarcity is not absence, but it is a warning label.