That is, by being certain about something, some claim about the world that in fact is not true. Because if I'm really nervous, say because I think there might be a predator, and someone convinces me, no, it's actually a rabbit appearing in the guise of a predatory cat, that might reduce my stress, but it's not an adaptation. Fair enough, fair enough. So Barbara, you gave us some history of where you think this may have begun all the way back in human history. What's your sense of why it has persisted for so long?