TIL

[timelets]

An isolated monkey will repeatedly pull a lever with no other reward than to glimpse another.

...

People who cannot usually detect violations of “if-then” rules can do so easily when the violation involves cheating in social exchange.

Neuroimaging experiments also show activation in brain areas used for reasoning about social exchange rather than in areas used for reasoning about logically similar behavioral rules.

-- quoted from Brian Boyd, On the origins of stories.