Why the (gene) counting argument fails in the massive modularity debate: The need for understanding gene concepts and genotype-phenotype relationships

Abstract

A number of debates in philosophy of biology and psychology, as well as in their respective sciences, hinge on particular views about the relationship between genotypes and phenotypes. One such view is that the genotype-phenotype relationship is relatively straightforward, in the sense that a genome contains the “genes for” the various traits that an organism exhibits. This leads to the assumption that if a particular set of traits is posited to be present in an organism, there must be a corresponding number of genes in that organism's genome to account for those traits. This assumption underlies what can be called the “counting argument,” in which empirical estimates of the number of genes in a genome are used to support or refute particular hypotheses in philosophical debates about biology and psychology. In this paper, we assess the counting argument as it is used in discussions of the alleged massive modularity of the brain, and conclude that this argument cannot be upheld in light of recent philosophical work on gene concepts and empirical work on genome complexity. In doing so, we illustrate that there are those on both sides of the debate about massive modularity who rely on an incorrect view of gene concepts and the nature of the genotype-phenotype relationship.

Keywords:

• Counting Argument
• Evolutionary Psychology
• Gene Concept
• Genome Complexity
• Genotype-Phenotype Relationship
• Massive Modularity

Notes

Notes

[1] Following Buller (2005), we distinguish between evolutionary psychology as a general approach to studying the mind from an evolutionary perspective (lower case ‘ep’), and the specific research program of ‘Evolutionary Psychology’ (capitalized ‘EP’) defended by Barkow, Cosmides, and Tooby (1992), Buss (1998), Cosmides and Tooby (1997), and Pinker (2002). Bechtel (2003, p. 211) draws a similar distinction using the terms ‘broad evolutionary psychology’ and ‘narrow evolutionary psychology’, respectively. We explicate MMT in section 2; for debates about MMT, see Carruthers (2004), Fodor (2001), Frankenhuis and Ploeger (2007), Machery (2007, 2008), Machery and Barrett (2006), Samuels (1998), Silvers (2007), Sperber (2002), and Woodward and Cowie (2004).

[2] These estimates are the only data Buller offers with respect to the relative complexity of the human genome, and he doesn’t provide references for those data. Strangely, as it would seem to strengthen his position, he does not discuss recent literature that puts the size of the human genome at a much lower estimate of about 25,000-30,000 genes. This much smaller number of genes was quite unexpected and was addressed in a wave of publications that appeared after the publication of the first drafts of the human genome in 2001 (Claverie, 2001; International Human Genome Sequencing Consortium, 2001; Szathmáry et al. 2001; Venter et al., 2001).

[3] We thank H. Clark Barrett for this point. See also Barrett & Kurzban (2006, pp. 639–641).

[4] It is generally accepted that the complications mentioned here occur quite commonly. Recent overviews can be found in Ast (2005), Griffiths & Stotz (2007), Portin (1993), Stotz et al. (2004), Waters (1994, 2007), Weber (2005, pp. 188–228), and Wieben (2003).