“ Given that you were primarily concerned with humans (and human inquiry), this may seem irrelevant but I think its actually quite germane. You see, humans ARE to a significant extent like trees. Like us, trees grow, trees take in nutrients, trees respond to changes in their environment, trees retain traces of prior occurrences in their lives, and so on. And they do all of those things (and more) without thinking. What that suggests is that much of what we do we probably do the same way trees do them, without thinking. In fact, there are lots of observations that indicate that that is indeed so. The "unconscious" is real, though not quite the beast that Freud (or people after him) made it out to be; see "Making the Unconscious Conscious, and Vice Versa").