isn't some ladder, with us at the top. We're just one creature out of
zillions, all of them doing OK just as they are. There was no special
magic that made us what we were when we were; we just happened to be the
right species in the right place at the right time. A lot of different
factors entered into it: the climate, the shapes of their hips, the
kinds of prey available, the relationship between savannah and forest,
etc etc etc. Every situation is different and there are literally
billions of alternatives.
If there's an evolutionary factor at
play in human "intelligence", it's only in that H. sapiens has somehow
decided to wipe out its fellow species at a rate 1,000 to 10,000 times
faster than the normal rate of it. That is indeed an evolutionary factor
that is selecting against them, but I hardly think it's a mark in favor
of intelligence that it's causing extinctions at an asteroid-like rate.
And it's exactly the kind of thing that can get this species to wipe
itself off the earth, leaving the cockroaches and the sea slugs to duke
it out in a newly-opened ecosystem. I wish them luck.