do instead of spending so much of their energy looking for seeds or worms? Perhaps possessing characteristic A rather than B was just a secondary consequence of a different developmental or biochemical property that was variable and heritable. Or perhaps characteristic A was the only available variation that differentiated the selected from the unselected organisms. It is these considerations that lie at the heart of Jerry Fodor and Massimo Piattelli-Palmarinis discussion of What Darwin Got Wrong.1Evolutionary biologists are of two sorts. A minority really do not care why one inherited characteristic confers a reproductive advantage to its possessors. They are content to show that such an advantage exists for a particular inherited difference, thus exemplifying natural selection. The dominant figure in experimental and observational evolutionary genetics in the middle of the last century, Theodosius Dobzhansky, spent most of his life showing convincingly from observations of both natural and experimental laboratory populations that natural selection was the cause of both the year-to-year stability and the repeatable seasonal changes in the proportions of certain variants in the chromosomes in natural populations of fruitflies.Despite spending time every year on horseback, visiting localities in the Great Basin and California where he trapped fruitflies, Dobzhansky never, in fact, saw a fruitfly in its native condition. He collected living flies by putting out rotting banana traps, so the flies came to him, but from where he never knew. When flies were brought back to the laboratory and bred in large populations in which the proportions of the chromosome types were initially very different from the ones found in nature, those proportions changed in repeatable ways in a few generations. It was sufficient for him to be able to demonstrate that natural selection really worked.In contrast, most evolutionary biologists work on natural populations of plants or animals that they have chosen because they believe they can tell a natural historical story of how selection actually operates in a particular case. The most famous example is the increase in the black form of the wings in the peppered moth that has occurred in England since the mid-nineteenth century. The explanation offered and repeatedly appearing in textbooks (although since called into question because of faulty methodology) was that the moths rested on tree trunks where they were at risk of being eaten by birds. Before the spread of heavy industry the tree trunks were covered with lichens whose speckled appearance was matched closely by the peppered appearance of the moths wings, so the camouflaged moths were only occasionally attacked. With the air pollution caused by heavy industry, the lichens were killed, so the moths were easily visible on the naked dark bark and were heavily preyed upon. A mutation to black wings appeared and was strongly favored by natural selection since the black-winged forms were now once again camouflaged.There is little doubt that this example, widely taught in lectures and textbooks, had a powerful influence in convincing evolutionary biologists who came into the field from their prior interest in natural history that one could tell the causal story of natural selection.