What intelligence is: thoughts inspired by dolphins

I have always been thinking about what intelligence is - because my research is about artificial intelligence. Basically, what do we really mean by the word ``smart''?

I had too much pizza for dinner today. Too sleepy, couldn't work. So I ended up watching PBS. PBS was playing Nature. The episode was called Ocean Giants, about dolphins and whales.

One thing remarkable I saw was dolphins in Florida hunting fish in shallow water. A female dolphin used her tail to stir mud to form a V-shape mud trap. Fish got trapped had nothing to do but jumping. Then dolphins on the other side of the trap just opened their mouths and enjoyed fish.

Watch Dolphin Mud Walls on PBS. See more from Nature.

Then I said, wow, this was really smart. And this technique has been passed in dolphins for generations.

So, i came up with a definition to ``intelligence'' that I had never thought about. Intelligence is the ability to use the environment for survival. Of course, this definition wouldn't be very sufficient and necessary. But I think it fits many cases where we use the word ``smart.'' Let's see a bad example. In movies, a lot of stories are about kids being kidnapped. ``Smart'' kids always escape.

One big flaw of this definition is that survival is not the only reason that human exercise intelligence. For example, we wanna know when and how the universe began. This does not have a strong and direct connection to survival - that's why most people don't always think about it.

So, why do we think? Besides for survival.