In California earlier this week, I had an odd experience: I heard a raven croaking, looked up to find it on a low branch, and stepped toward it. The bird watched me but did not move. It was huge, almost two feet tall, with a large, slightly curvy beak and yellow eyes. I'd never seen anything like it. I came closer, but the bird didn't really care - it just kept croaking, and listening as another raven, in a nearby tree, croaked back. I had the feeling I was in the presence of some kind of intelligence -- not just another bird.

Turns out, ravens are as smart as two-year-olds. They are flexible, strategic thinkers. They'll even try to make a bested rival feel better. Wow.