Addressing Cumulative Selection

摘要

In his unfavorable review ("god as genetic engineer," Books et al., 8 June, p. 1427) of my book, The Edge of Evolution (1), Sean Carroll writes that "Behe's chief error is minimizing the power of natural selection to act cumulatively," and implies that I fail to discuss "pyrimethamine resistance in malarial parasites ... —a notable omission given Behe's extensive discussion of malarial drug resistance." The insinuation is that I included only what fit my purposes. Yet I explicitly discuss multiple mutations of pyrimethamine resistance: "Although the first mutation (at position 108 of the protein, as it happens) grants some resistance to the drug, the malaria is still vulnerable to larger doses. Adding more mutations (at positions 51,59, and a few others) can increase the level of resistance" [(1), p. 79]. In the same section, I also discuss the development of insecticide resistance in mosquitoes by "tiny, incremental steps—amino acid by amino acid—leading from one biological level to another." Furthermore, in other sections, I describe a cumulative Darwinian route to antifreeze proteins and extensively address hemoglobin C-Harlem to illustrate the crucial difference between beneficial intermediate mutations and deleterious intermediate ones.