A Mind Fit for Mating G.F. Miller The Mating Mind, Ch 4 (2000)

Main Thesis Human mental abilities shaped by sexual selection not natural selection Not necessarily optimal or rational

Sexual Selection Goal - choose mate with best genes for offspring Feedback loops –Runaway selection –Fitness indicators Produces traits not optimal for survival

Runaway Selection Arbitrary preferences self-reinforce Target sex must develop trait Selecting sex need offspring with trait Produces marked dimorphisms

Fitness Indicators Traits with strong correlation to overall fitness Draw on large fraction of genome Exogenous pressure for preference Leads to exaggerated manifestation Human brain –Affected by 50% of genes –Disproportionate energy use, x10-30 –Rapid tripling in size

Heritability of Fitness Mate selection only useful with meaningful genetic variation Absent in evolutionary equilibrium But mutations, shifts in environment

Reliable Indicators Selective pressure to fake Only useful if –Direct indicator of fitness –Incur cost Handicap principle –Wasting resources is reliable indicator of fitness

Mental Traits as Fitness Indicators Traits not shared with other primates –Music, humor, creativity –(excess) language, altruism Characteristic of sexual, not natural, adaptations –Large individual differences, non-modular, heritable, high costs, complex