Biology is the science. Evolution is the concept that makes biology unique.

Diamond’s aphorism distinguishes between biology as a descriptive, empirical discipline (“the science”) and evolution as the unifying explanatory framework that gives biological facts their coherence. The point is not that other sciences lack organizing theories, but that biology’s central questions—why organisms are the way they are, why traits persist or disappear, why life shows both unity and diversity—are uniquely illuminated by historical processes of descent with modification. Read this way, the quote argues that biology becomes more than cataloging organisms once it is interpreted through evolutionary thinking, which turns observations into explanations about adaptation, constraint, contingency, and common ancestry.