a b s t r a c t One leading edge of intellectual exploration that Tom Bouchard significantly contributed to lies at the interface of behavior genetics and evolutionary biology. Behavior geneticists have amply demonstrated that most important psychological individual differences owe part of their variance to genetic variants. An interesting issue from an evolutionary perspective concerns why meaningful genetic variation persists. Evolutionary biology offers a number of possible answers. I examine arguments and currently available data that speak to their application to variation in personality. Some likely answers (e.g., stabilizing selection is opposed by generation of new mutations) were conjectured b
