The gene, not the individual, is the unit that matters

Dawkins's central move is to shift the camera from the organism to the gene. Bodies are temporary and get shuffled apart every generation, but a gene, or at least its exact sequence, can in principle be copied forever. So natural selection, he argues, is best understood as competition between genes for representation in future generations, with bodies as the vehicles they build to get there.

This isn't a claim that genes have intentions — Dawkins is explicit that "selfish" is a shorthand, not a psychology. A gene that happens to build bodies which behave in ways that help copies of itself survive will spread, whether or not anyone or anything "wants" it to. Genes that build bodies which behave self-destructively vanish.

The payoff is explanatory power: instead of asking "why is this good for the species," biologists started asking "why is this good for the gene," and suddenly puzzling behaviors — infanticide, sibling rivalry, self-sacrifice — started making sense.

Takeaway: when behavior looks irrational at the level of the individual, check whether it makes sense at the level of the gene.