 But how, then, the reader is entitled to ask, can Kuhn accommodate the sharp discontinuities that he advertised in chapter X of the book? We cannot equate revolutions simply with speciation in Darwin’s own sense, given that Darwin’s favorite mechanism of speciation was anagenesis, not cladogenesis—just the long-term gradual evolution within a single line rather than the splitting of lines. Interestingly, the later Kuhn will opt for cladogenesis.