Does evolution lead to maximizing behavior?

Abstract

A long-standing question in biology and economics is whether individual organisms evolve to behave as if they were striving to maximize some goal function. We here formalize this "as if" question in a patch-structured population in which individuals obtain material payoffs from (perhaps very complex multimove) social interactions. These material payoffs determine personal fitness and, ultimately, invasion fitness. We ask whether individuals in uninvadable population states will appear to be maximizing conventional goal functions (with population-structure coefficients exogenous to the individual's behavior), when what is really being maximized is invasion fitness at the genetic level. We reach two broad conclusions. First, no simple and general individual-centered goal function emerges from the analysis. This stems from the fact that invasion fitness is a gene-centered multigenerational measure of evolutionary success. Second, when selection is weak, all multigenerational effects of selection can be summarized in a neutral type-distribution quantifying identity-by-descent between individuals within patches. Individuals then behave as if they were striving to maximize a weighted sum of material payoffs (own and others). At an uninvadable state it is as if individuals would freely choose their actions and play a Nash equilibrium of a game with a goal function that combines self-interest (own material payoff), group interest (group material payoff if everyone does the same), and local rivalry (material payoff differences).

Inclusive fitness is an indispensable approximation for understanding organismal design

“…A number of authors have shown that, for example, in a simple nonadditive two player game, such naïve versions of inclusive fitness wrongly predict the direction of gene frequency change (Grafen ; Queller ; Lehmann et al. ; Okasha and Martens ; Taylor ).…”

“…Several authors (Grafen ; Lehmann et al. ; Okasha and Martens ; Allen and Nowak ; Frank ) have also pointed out that using Hamilton's “neighbor‐modulated fitness” (NMF) resolves this problem in some scenarios (although these authors do not always acknowledge that they are dealing with NMF, instead referring to it by other names, such as “Grafen‐1979 payoff,” which is just NMF in a two player game). This is not surprising as NMF is simply mean number of adult offspring (it adds to the focal individual's fitness the offspring it would receive if its social partners expressed the same phenotype, weighted by the probability that they will, that is, the population frequency of altruism enhanced or diminished by relatedness).…”

“…NMF's ability to make the right prediction under a wider range of circumstances has led several authors to suggest adopting offspring number (under its various guises) in place of inclusive fitness (Lehmann et al. ; Okasha and Martens ). However, we proceed to discuss the ways in which mean offspring number is inferior to inclusive fitness with regards to the other advantages.…”

“…Levin and Grafen (Submitted) have shown formally that additive models are consistent with a very wide range of situations, and that inclusive fitness maximization does occur in model circumstances in which previous authors (Lehmann et al. ; Okasha and Martens ) have failed to find it. Here, we focus on the less technical but broader conceptual arguments in support of those formal results, in a way that is accessible to nonmathematicians, and contains practical advice for empiricists.…”

There is no fitness but fitness, and the lineage is its bearer

“…1 Technically, this expectation is taken over the stationary distribution of the branching process describing the dynamics of a mutant lineage [23]; see Lehmann et al [24] for an example. 2 Up to a transformation with the average reproductive value of the residents [23].…”