It’s about time that someone explained stupidity. As the opening says:

Only a few questions can be called basic to the human condition — such as “What can we eat?” or “Who created us?” — and lots of very smart people have been working on them for millennia. The “eating” thing, for instance, has been minutely parsed by agriculture, economics and the culinary arts (among other fields), while the question of origins has given us religion and several branches of the hard sciences. But there’s at least one question — as basic as any other in its topical relevance and its grounding in the ancient — that human inquiry has only recently begun seriously to address. It was asked in caves, by people clad in mastodon-hide shifts, and chances are it crossed your mind this very day. “How,” it goes, “can people be so stupid?” And who knows the answer, really? I don’t — do you?