[lngnmn]

The classic AI (as in the AIMA book), it seems, got it right - heuristic-based search, guided by feedback (to improve an heuristic) is what intelligence is in general. Every living organism posseses intelligence (by the process of trial-and-error, which is a search, to "learn" an "optimal" heuristics with selection by the process of evolution) of some kind relative to its environment. This is how a bacteria fought viruses, for example.

The problem is to find a good-enough heuristic, or to "extract" one from the actual (not imaginary) features of the environment and "train" it. This is, roughly, how ensimes has been made.

This second goal is murderously hard, because to select right set of features which adequately represent some aspects of reality (as it is, not as we imagine or know it is) is where humanity is still failing miserably.