When I was little, I was surprised that lizards could behave so intelligently, even though their brains and bodies are so small. Their eyes, always keeping an eye on me no matter where I went in my Floridian backyard, would move around and track me, seeming more alert--even more ‘alive'--than our own human eyes often do. I was even more surprised (shocked, actually) when I saw that a lizard's tail, when detached from the lizard's torso, moves about vigorously, jumping around and looking like a living thing. This unfortunate event for both the lizard and the catcher happens when one tries to catch a lizard from behind but, because of the lizard's speed, ends up empty-handed, with one's fingers failing to reach past the hind legs, making contact only with the tail.

The grown-ups around me explained to me that the detached tail (which grows back, they assured me) moves because it has some residual "life force" from the lizard's body. Years later I learned the truth--that the tail moves because of the activities of excitable nerve cells (neurons) contained within it. These neurons wiggle the detached tail so that a predator becomes enthralled by its movements and forgets about the more important parts of the lizard (the brains, lungs, gametes) that are running away at that moment. Greater was the realization that, whatever makes the detached tail move also makes the lizard's brain work the way it does, giving rise to, for example, its intelligent eye movements. More shockingly was the acknowledgment that the same kind of cells make my own brain work the way it does, with its perceptions, memories, desires, and conscious experiences.