Some Research Shows Night-Owls are Smarter

The (hypothesized) explanation is contained in the abstract: “Survey of ethnographies of traditional societies suggests that nocturnal activities were probably rare in the ancestral environment, so the Hypothesis would predict that more intelligent individuals are more likely to be nocturnal than less intelligent individuals.”

That is: Individuals with higher intelligence are more likely to make choices in their lives that are different from our evolutionary history. Thus, one would expect that the group of people who choose to be (for example) more nocturnal in nature would tend to consist of a higher than average number of people of higher than average intelligence. I suppose this isn't surprising, but I'd suggest that one should not turn this around and suggest that individuals who are night owls are smarter than individuals who are not. That doesn't follow. The hypothesis says nothing about individuals. (A person who likes to stay up late partying because that's when the clubs are open is not necessarily smarter than average.)