Anya Plutynski

Natural selection is an extremely powerful process – so powerful, in fact, that it is often tempting to deploy it in explaining phenomena as wide-ranging as the persistence of blue eyes, the origins or persistence of religious belief, or, the history of science. One long-standing debate among both critics and advocates of Darwin’s concerns the scope of Darwinian explanations, and how we are to draw the line. Peter Godfrey-Smith’s Darwinian Populations and Natural Selection is a detailed examination of this question. The book explores the criteria for what may count as a “Darwinian population,” by which Godfrey-Smith means, which collections of entities have the capacity to undergo evolution via natural selection (p. 6). Drawing upon his answer to this question, Godfrey-Smith examines and provides his own solution to the following long-standing debates in philosophy of biology: (a) the twin problems of reproduction and individuation of biological entities, (b) the persistent “gene’s eye view,” (c) the levels and units of selection problem, and (d) the evolution of cultural artifacts and behaviors.

There have been two different schools of thought on the evolution of dominance. On the one hand, followers of Wright [Wright S. 1929. Am. Nat. 63: 274–279, Evolution: Selected Papers by Sewall Wright, University of Chicago Press, Chicago; 1934. Am. Nat. 68: 25–53, Evolution: Selected Papers by Sewall Wright, University of Chicago Press, Chicago; Haldane J.B.S. 1930. Am. Nat. 64: 87–90; 1939. J. Genet. 37: 365–374; Kacser H. and Burns J.A. 1981. Genetics 97: 639–666] have defended the view that dominance is a product of non-linearities in gene expression. On the other hand, followers of Fisher [Fisher R.A. 1928a. Am. Nat. 62: 15–126; 1928b. Am. Nat. 62: 571–574; Bürger R. 1983a. Math. Biosci. 67: 125–143; 1983b. J. Math. Biol. 16: 269–280; Wagner G. and Burger R. 1985. J. Theor. Biol. 113: 475–500; Mayo O. and Reinhard B. 1997. Biol. Rev. 72: 97–110] have argued that dominance evolved via selection on modifier genes. Some have called these “physiological” versus “selectionist,” or more recently [Falk R. 2001. Biol. Philos. 16: 285–323], “functional,” versus “structural” explanations of dominance. This paper argues, however, that one need not treat these explanations as exclusive. While one can disagree about the most likely evolutionary explanation of dominance, as Wright and Fisher did, offering a “physiological” or developmental explanation of dominance does not render dominance “epiphenomenal,” nor show that evolutionary considerations are irrelevant to the maintenance of dominance, as some [Kacser H. and Burns J.A. 1981. Genetics 97: 639–666] have argued. Recent work [Gilchrist M.A. and Nijhout H.F. 2001. Genetics 159: 423–432] illustrates how biological explanation is a multi-level task, requiring both a “top-down” approach to understanding how a pattern of inheritance or trait might be maintained in populations, as well as “bottom-up” modeling of the dynamics of gene expression.