I received a welcome email about the "hypothetical evolution of a human capacity for a playful or fantasy mode of cognitions and its relation to the use of hypnosis clinically." My goodness.
a) Jacob Bronowski (A Sense of the Future, MIT Press, but out of print) spoke about the elaboration of a fundamental change - the ability to delay behavior. This delay accomplishes neurally the same thing that is accomplished hormonally and by other mechanisms (spores can wait millennia), a bit of a delay is created between stimulus and output. This delay per Bronowski becomes the basis for thinking, elaboration of language, planning, a sense of the self, a sense of time, emotional regulation (inhibition or kindling), and the capacity to analyze events into component parts and to synthesize them into new, more useful arrangements. These "Executive Functions" represent one instance of a splitting of cognition from a strict dependence on external events. (Russ Barkley, cited elsewhere, does a convincing job of using this model as a germinal model of ADHD, one that is more relevant than the "watch 'em fidget" one.)
b) Dreams are another separation of sensation from cognitive manipulations. Some of mine are fairly playful, others make me waken at 3 AM with ideas for my notepad.
c) It's a major help to separate my mind from my body during long runs. I've posted elsewhere about Psychological Adaptations, Executive Functions, and their basis in long distance runs, perhaps while chasing game. You have to imagine where the target may be in 10 minutes or in a week and get to that spot ahead of it. The modern equivalent, of course, involves other sorts of mental activity such as imagining I'm rescuing a hijacked plane, riding on a probe to Mars, or running with Uta Pippig (3 x winner of the Boston Marathon, female division, who still manages to look like a girl). More lately, the dream is that I'm part of a Marine unit and all 24 of us are going up a tough hill together.
d) Another hypnotic experience occurred when a friend and I transplanted 200 maple saplings. Charlie advised, "Talk smut and we won't get tired." We did and didn't. And none of the trees died.
e) My mind is rarely integrated when driving the Z. My feelings and thoughts are more consistent with age 35 rather than 55; it's disconcerting to look in the rearview mirror and I avoid it.
f) The posting on "Memories" in the depression material is one more example wherein older, more positive memories over ride current, defeating ones.
All in all, there are so many Psychological Adaptations (cognitive modules) that integration and synchrony are larger miracles than the independent islands of mental activity associated with dreams or hypnosis. It's been known for some time that even a small slab of neurons will exhibit a fairly normal EEG. Nerve cells fire and in groups, fire in coordinated waves due to lateral inhibition between them. Such inhibition seems to account for bursts of waves and for suppression of competing waves.
Given that images and sounds can be activated by internal command (free association or triggered memories), there is no great surprise that they can also be triggered by an outside command sequence as in hypnosis or by an instructor's demand for a recitation of the events leading to the War of 1812.
With respect to evolution ... evolution is about increasing the number of kids you produce and rear to the point of reproducing themselves. It's also about doing it more abundantly than other creatures who are similar to but not identical to you. If I have to include evolution as a constraint, then I'd stick with the Executive Functions as the major factor and fun fantasy and hypnosis as spandrels, goodies that are possible because of the original adaptation but that may have little adaptive value of their own. (1)
Evolution and Psych Adaptations perhaps have some value to hypnotists by sluggesting imagery with more powerful, more primitive content that will override anxiety of kind or another. Incidentally, this is something of a wager because many anxieties may themselves be a reflection of evolutionarily important Psychological Adaptations.
1) You could remember that dreams and fun have stress-reducing value and should help us live longer. I will never give up my own, however, the real chips in evolution are those that are played in our younger years when we produce children. Peter Medawar taught us that many syndromes of middle age were never the target of natural selection because we had already produced kids before we got sick.