If you’re a woman on a date with a man (this test may not work as well the other direction) and you want to get a sense of how intelligent he is, just ask this: what historical periods are you interested in? A smart, interesting man will answer the question easily and eagerly, excited that you asked. But if he can’t answer it or says something vague or names some historical subject but then can’t explain why he finds it so fascinating, that’s a very good sign that you’re on a date with a shallow, incurious, dumb, boring guy who doesn’t read.