Gene Expression

Evolution and trustworthiness

Evolution of trust and trustworthiness: social awareness favours personality differences (Open Access):

Interest in the evolution and maintenance of personality is burgeoning. Individuals of diverse animal species differ in their aggressiveness, fearfulness, sociability and activity. Strong trade-offs, mutation-selection balance, spatio-temporal fluctuations in selection, frequency dependence and good-genes mate choice are invoked to explain heritable personality variation, yet for continuous behavioural traits, it remains unclear which selective force is likely to maintain distinct polymorphisms. Using a model of trust and cooperation, we show how allowing individuals to monitor each other’s cooperative tendencies, at a cost, can select for heritable polymorphisms in trustworthiness. This variation, in turn, favours costly ‘social awareness’ in some individuals. Feedback of this sort can explain the individual differences in trust and trustworthiness so often documented by economists in experimental public goods games across a range of cultures. Our work adds to growing evidence that evolutionary game theorists can no longer afford to ignore the importance of real world inter-individual variation in their models.


The fact that evolutionary psychology traditionally focuses on universal traits which are genetically fixed while behavior genetics is preconditioned on heritable variation of similar traitshas been a distinction which has been brought to light by skeptics of any biological component to human behavior. In The Undiscovered Mind John Horgan attempted to throw cold water on the rise of neuro and cognitive sciences precisely using this sort of tactic. Though I think many critics of evolutionary psychology argue in bad faith, at the end of the day some of their criticisms land on target because of the huge sample space of laugh-out-loud “theorizing” by scholars fixated on an outmoded paradigm.

Humans are not the same. We vary. And we vary in part because of heritable biological factors. Some evolutionary psychologists, Satoshi Kanazawa comes to mind, work under an old model where deviations from their expectation of human modal behavior is treated simply as trivial holdovers along the transient from the ancestral to the derived phenotype, or noise introduced by environmental factors. Because of he elegant simplicity of their model evolutionary psychologists of this school are expert verbal showmen.

Certainly there are plenty of human universals. But there are plenty of non-universals. We are familiar with the Red Queen hypothesis in relation to our immune systems. This model arose in large part because of the necessity for constant evolution in the forever war with parasites. If humans are a cultural animal par excellence for whom the flexibility of their behavioral toolkit is essential, should it surprise us if frequency dependent evolutionary dynamics result in a large number of morphs constantly cycling? Perhaps H. sapiens is the environment of evolutionary adaptedness of H. sapiens?

Related: Heritability of the Ultimatum Game, Altruism and Risk-Taking: Kinda Heritable and Variation as the ultimate.