Population thinking and natural selection in dual-inheritance theory.

Wybo Houkes

doi:10.1007/s10539-012-9307-5

Abstract

A deflationary perspective on theories of cultural evolution, in particular dual-inheritance theory, has recently been proposed by Lewens. On this ‘pop-culture’ analysis, dual-inheritance theorists apply population thinking to cultural phenomena, without claiming that cultural items evolve by natural selection. This paper argues against this pop-culture analysis of dual-inheritance theory. First, it focuses on recent dual-inheritance models of specific patterns of cultural change. These models exemplify population thinking without a commitment to natural selection of cultural items. There are grounds, however, for doubting the added explanatory value of the models in their disciplinary context—and thus grounds for engaging in other potentially explanatory projects based on dual-inheritance theory. One such project is suggested by advocates of the theory. Some of the motivational narratives that they offer can be interpreted as setting up an adaptationist project with regard to cumulative change in cultural items. We develop this interpretation here. On it, dual-inheritance theory features two interrelated selection processes, one on the level of genetically inherited learning mechanisms, another on the level of the cultural items transmitted through these mechanisms. This interpretation identifies a need for further modelling efforts, but also offers scope for enhancing the explanatory power of dual-inheritance theory.

Highlights

A deflationary perspective on theories of cultural evolution, in particular dual-inheritance theory, has recently been proposed by Lewens
Where most of the controversies focus on commitments that theories of cultural evolution need to express in order to count as ‘properly’ or ‘genuinely’ evolutionary or selectionist, Lewens focuses on the commitments that these theories need in order to be of disciplinary interest
Building on Mayr’s (1976) discussion of Darwin’s great contributions to biology,2 Lewens argues that the best current efforts to extend Darwinism mainly apply population thinking to cultural phenomena, without necessarily claiming that cultural items evolve by natural selection, or that they are subject to Darwin’s hypothesis of common ancestry

Summary

Population thinking and natural selection

To prepare the grounds for our arguments against the pop-culture analysis, it needs to be made clear how and to what extent population thinking can be differentiated from the principle of natural selection. Both models exemplify population thinking, in focusing on relevant differences in or features (sizes) of human populations, and apply insights from DIT in focusing on the effects of basic social-learning mechanisms. Neither model features the operation of natural selection on populations of cultural items These DI models of cultural change fit the pop-culture analysis just as well as the basics of DIT summarized in the previous section. Some reasons were given to be cautious about the explanatory value of both of Henrich’s models These do not amount to arguments for abandoning the strategy of constructing DI models for patterns of cultural change, let alone for rejecting any theory of cultural evolution. We present one way to implement this strategy, which is suggested in some narratives used to motivate DI theory, but that contributes to specifying—in terms of natural selection—the phenomenon of cumulative cultural change

Cumulative cultural change and explanatory adaptationism

Three objections to natural selection of cultural items