Here is the theory I have arrived at. Humans are successful animals because we have developed large brains with the capability of identifying and matching patterns of many varieties. These patterns could be called concepts, or theories, or hypotheses, or just rules of thumb. The patterns can range from the highly concrete (“a chair”) to the social (“a family”) to the philosophical (“happiness”).
Evolution equipped us not only with the ability to handle patterns but also a reward mechanism for exercising it, which like other reward systems takes neurochemical form. You will know this as the “Eureka” moment when something suddenly “makes sense” (meaning you found a new pattern it fits into, or an old one, or a modification to an old one), or, less dramatically, the little satisfying mental click when something falls together.
Although it is not directly related to my overall topic here, the human inclination, or one might say compulsion, to believe in God can be tied to this neurotheoretical notion of pattern-finding and pattern-matching (and thus the somewhat unfortunate term “neurotheology”), in the sense that a belief in God again activates our reward systems for finding patterns, in this case a “pattern” or framework that ties together disparate and otherwise unexplainable things. Of course, this fundamental biological motivation that results in a notion of the supernatural is then embroidered and modulated by any number of social and political factors, and people have written entire books on the subject, but underlying it all is the human thirst to understand (in other words, find patterns), which, again, has a neurobiological basis.
Thirst in the very real sense, because reward is the flip side of desire, be it for water or anything else, and desire merely one stage on the path to addiction. Those neurochemicals sloshing around in our brains making us feel great when we have sex are also capable, by their absence, of making us sad, horny, jittery, or desperate. It is when this deprivation becomes so serious that we seek to satisfy it, even at great cost to ourselves, that we call it addiction.
Evolution made a wise enough choice in developing these mechanisms; they mostly serve us well when it comes to nourishment, or reproduction, or social relationships, or even intellectual pursuits, such as in the urge Einstein felt to discover the pattern which resulted in the theory of relativity. But what purpose is served by the deep emotional unease, pain, or even agony, that we feel when we are unable to satisfy our cravings for finding patterns, especially big patterns, or the biggest pattern of all, which is how all these other patterns fit together–the “meaning of life” (yes, patterns are essentially identical to what we call “meaning”)–even in the case where there is no pattern to be found? (The millions of people who are desperately seeking the big pattern by pursuing whatever form of religion or practice or devotion or philosophy are, at one level, hardly different from the crack addict furiously looking for his next fix. Of course, just as not everyone develops an addition to drugs, not everyone develops an addiction to finding patterns. In both cases, I suppose it is, like most other things, a matter of so-called epigenetics.