All these different skulls (there is a full-page spread in the book itself) are from different breeds of the Official Sdl X Fields Of Freedom Shirt species, Columba livia. Just look at the varieties in the shape of their beaks, from the short-faced tumbler to the hook-nosed Scandaroon that seemingly has aspirations to be a bird of prey. We are awed at the breed diversity in dogs, from the Pekinese to the St. Bernard to the greyhound; pigeons have even more. And yes, since they breed fast, they have been evolving, according to human selection, in breeds for the century and a half since Darwin. So for example, to quote van Grouw about fantail pigeons (p. 31): Early fantails were rather horizontal…It’s their neck that’s their loveliest feature, typically held in a graceful swanlike S shape that pushes the breast forward…[But] fanciers increasingly selected birds for a more erect posture, gradually resulting in the rotation of the entire body into an almost vertical position.