Dynamical systems and mating decision rules

Dynamical simulations of male and female mating strategies illustrate how traits such as restrictedness constrain, and are constrained by local ecology. Such traits cannot be defined solely by genotype or by phenotype, but are better considered as decision rules gauged to ecological inputs. Gangestad & Simpson’s work draws attention to the need for additional bridges between evolutionary psychology and dynamical systems theory. What would the world look like if women were as unrestricted as men? Attraction patterns in male homosexuals are in many ways similar to those of heterosexual men. Both, for example, emphasize attractiveness over status and both change preferences from relatively older to younger partners with age (Bailet et al, 1994; Kenrick et al, 1995). But homosexuals’ partners are, on average, as unrestricted as they are. Gay men who contracted AIDS during the 1980s had an average of 1100 partners, and those without AIDS had several hundred (Michael et al, 1994). In constrast, the mean lifetime total for heterosexual males is 12; most men having fewer than 5 (michael et al, 1994; Smith, 1994). But over 70% of men accepted a female stranger’s invitation for sex in one field experiment, suggesting things might change if heterosexual men had more offers (Clark & Hatfield, 1989). Such statistics support Gangestad & Simpson’s (GS in all others, the result was a mixed, but spatially organized, arrangement in which a minority pocket was segregated from a majority (as in Fig.2). Such stable organized patterns, in which local majorities draw in neighboring cells, are ubiquitous in networks of all kinds, and mirror many natural systems. Published in Behavioral and Brain Sciences, 2000, 23 no. 4, pp. 607-608. http://dx.doi.org/10.1017/S0140525X00453379 2 Thinking in dynamical terms draws attention to a point often made by evolutionary and/or personality psychologists – that a “trait” is not a rigid locked-in setting, but a variable decision-rule keyed to the environment. An individual predisposed towards unrestrictedness, for example, may act restricted in contexts where opportunities disallow unrestricted behavior, and vice versa. Consider what happends to the system depicted in Figure 1 if females used a male decision-rule for change (see Fig.3). Note that, at the “genotype” level, males did not change their “traits” in any way, but their behavior was phenotypically very different when local females adopted different decision rules. A key point implied by a dynamical analysis is that “restrictedness” need not be locked in at birth, or by early experience, but could be a decision-rule shared by all individuals of a given sex, manifesting itself in different overt behaviors depending on local ecological circumstances. As G&S indicate, decisional possibilities will vary with chronic social characteristics of the individuals involved. However, once a local system stabilizes, individual differences have minimal impact. An unrestricted individual dropped into the majority pocket of restrictedness in Figure 2, for example, would adopt a restricted strategy, and the converse would be true for a restricted individual dropped into a stable unrestricted area. We are not suggesting that individual differences are irrelevant in such dynamical systems, however. Indeed, just a few females adopting an unusually unrestricted strategy, or a few males adopting an especially restricted strategy, could result in very different outcomes at the neighhorhood level. Mating decisions inherently unfold in a dynamical context. Given that evolutionary psychologists and dynamical systems theorists both aspire towards a comprehensive paradigm for the social and life sciences, it is essential to develop more conceptual bridges between them.