The modern history of biology shows how Darwin's selectionist theory has replaced instructionist theories in explaining the operations of living things: first with inheritance through the gene pool of the 1850s, and second with the replacement of a template theory of immune system function in the 1960s. Today scholars in several disciplines consider the brain a Darwin machine also. Underpinning Darwinism is a generative heuristic in which entities (or variants) are generated and later subjected to tests. Entities that survive the testing are re-generated. The premise of this paper is that the nature of both science and its learning can be understood through the application of this heuristic. The paper begins with an exposition of Darwin's conceptual synthesis and the recognition of its fundamental biological principles--generation of variants and selection from among those variants--in three specific domains. That recognition suggests the fruitfulness of these principles for understanding brain operation in general and generative learning in science in particular. The second section describes this biological view of learning and its three central characteristics. The last section initiates discussion of the worth of this biological basis for generative learning. Contains 57 references. (Author/PVD)