Re. measuring intelligence, do we really have any good direct measures? Fitness, as I think you allude to, is only indirect, and quantifying how much can be attributed to any one characteristic can be rather tricky (possibly an understatement).
Generally tho, I’d say a good measure of intelligence would be creating a system that can successfully tackle all problems a human can tackle - not task-specific solutions, but a general problem solver and task-doer. Possibly a very dead-average human, for that matter. It’s a lot of stuff, I guess: finding your way, puzzles, working, learning, talking, making some kind of rough sense of the world, stuff like that. Something like that. Fuzzy as all hell, all of it. As far as I can tell, AI struggles mightily with even single, specific tasks (e.g. driving a car), and often relies on workarounds (one car-driving AI knows every damn detail of all roads it drives on, iirc? Which kinda reduces the amount of actual problem-solving involved…).
