I have stumbled upon an article "Perceptual Pleasure and the Brain" by Irving Biederman and Edward Vessel discussing the role of endorphins in cognition. It appears that our brain craves novelty, and learning is associated with pleasure via opioid receptors in the brain. This can be a mechanism for survival and for evolutionary success.
What the authors do not discuss is the possible habituation of opioid receptors by continuous stimulation. This can be the result of addiction to drug opiates, but we also know that gluten and casein break down to peptides which bind to opioid receptors in the brain. This is one reason why we crave these foods after all. Interestingly, long distance running or cycling on a regular basis also releases endorphins, leading to mild addiction (I experienced this myself).
Now, with our receptors desensitised by grains, dairy and threadmills, we might need stronger stimulation to enjoy learning or we lose interest in learning altogether.
Opium for the masses?
If indeed the dietary derived opiates have any significant impact on brain function, it would explain why Paleo people are so hungry for knowledge, as evidenced by the high calibre discussions on blogs such as WholeHealthSource, Panu or FreeTheAnimal :)
Perceptual Pleasure and the Brain
(If you Google the title you can find the full text of other sites, such as:
Regarding food and thought, I have been thinking a lot about the possible POSITIVE impact of high carbohydrate diet (even with the harmful effects of grains) after the Neolithic revolution. I imagine that glucose (though not fructose) loading can be very good for brain FUNCTION short to medium term (before the degeneration sets in). Brain thrives on glucose and can be turbo charged with more carbs in the diet. Even if that would not mean optimal HEALTH overall, it could mean more brain power for competitive advantage! The analogy would be that maximum fitness does not equal otimum health and longevity (as brilliantly laid out by John Little in Body by Science). For the same reason using stimulants, such as cocoa or coffee (and sugar too!), can translate into more effcient thinking, better strategic planning? Something that the carb lobby can consider in their PR :)