Here is another excerpt from Temple Grandin's Animals in Translation.
"Physical movement is probably what caused the brain to evolve in the first place. Dr. Rodolfo Llinas, a neuroscientist at NYU who wrote I of the Vortex: From Neurons to Self, says the brain evolved because creatures needed a brain to help them move around without knocking into things. He gives the sea squirt as the ultimate example of what having a brain is all about. The sea squirt is a primitive organism with about three hundred brain cells that starts out looking something like a tadpole, and ends up looking a little bit like a turnip. For the first day of its life it swims around until it finds a permanent spot to latch on to. Once it finds its spot, it doesn't move again for the rest of its life.
Here's the interesting part: while it is swimming it has a primitive nervous system, but once it becomes attached to an object it eats up its own brain. It also eats its own tail and tail muscles. ...
Dr. Llinas's theory is that we have brains so we can move."
It makes sense, I suppose, that if one is permanently attached, living is about ingesting and eliminating and that's about it, but most of us invite a little more quality of life than that, so it is to consider what's involved with our brains when we move through an environment. It is quite lovely to think of the joy of seeking, searching, and the awareness that we are two sides of the hunt.