Not quite convinced. What if less intelligent people become conditioned to being less trusting, because they've been taken advantage of more often. The metrics are a bit unconvincing, too, and the results aren't exactly striking. Therefore, this:
is a bit premature. Natural selection? Trading partner? Given that trade can be measured in millenia without using all of your fingers and toes, I highly doubt it.The finding that generalized trust is highly correlated with intelligence, even after conditioning on socio-economic characteristics such as marital status, education, and income, supports the hypothesis that being able to evaluate someone’s quality as a trading partner is a distinct component of human intelligence, which evolved through natural selection