Civilization also can mean high population density, far more intricate social networks and occupations, intensified warfare, possibility of better nutrition, mo

Civilization also can mean high population density, far more intricate social networks and occupations, intensified warfare, possibility of better nutrition, more need for long-term planning to save up money and manage agriculture, etc. (Of course, civilization can also work the other direction as the past few centuries suggest. That there might be a long run trend to select on intelligence doesn't mean that there are no short-run trends select against it.)