This is a fascinating book: What Shamu Taught Me About Life, Love, and Marriage, which was spawned by Amy Sutherland's NYTimes article, "What Shamu Taught Me About a Happy Marriage."

This passage, and a particular line near the end, struck me while reading today:

Humans are so sloppy, I think, because we can later explain ourselves, put it another way, or apologize to our fellow higher primates. There's no explaining anything to an animal. If a trainer's timing is off and he unintentionally teaches a dolphin to jump when he meant it to flip, there's no explaining to the marine mammal, "Oh, jeez, sorry, what I meant was . . ." If a trainer unnerves an animal by getting too close too fast, he doesn't get to explain that he just wants to be friends. When a trainer falls down in front of a big cat, he doesn't get to explain it was an accident, that he's not a prey animal.

That animals take the world literally, connect the behavioral dots on the spot, and respond so clearly, drives home this fact: What you do is communication. If it wasn't so, we couldn't train animals. But we can, and without one word.