> Thus if intelligence is a factor at all in survival (and it seems like it should be) your ancestors may not have had a choice but to select for intelligent.

And this explains the large collection of (in our understanding) not-terribly-intelligent creatures on the planet how?

Not trying to be snarky, just pointing out that intelligence is just one of many paths, and it's very hard to have strong conclusion about how something so rare fares in evolution, and if the tend will maximize or if it pays off to be "just a little" intelligent, just like it pays to be "just a little" able to swim.

There's also the possibility that our concept of intelligence is totally wrapped up in our very anthropomorphic worldview. And we're simply incapable of understanding forms of intelligence that aren't distinctly our own.

Thus my "in our understanding" - I personally believe our view of intelligence, sapience, and self-awareness is pretty limited even from what we CAN relate to. It is easier to go through life we if assume the status quo of understanding.

I didn't mean to imply intelligence was a large factor, it need not be. There are thousands of factors, some more important than others. Some are even in direct conflict (intelligence is in fact in direct conflict with not needing too much energy to survive hard times - even while potentially providing more energy for those hard times). What humans have found successful doesn't say anything about about what any other animal will/should find successful.