A Big, But Slow Brain

The human being seems to make decisions in two disparate parts of the brain: the more primitive, sub-cortex region and the more recently-evolved outer cortex. The decisions coming from those two areas are quite different in character. The sub-cortex (the part we share with primordial vertebrates) makes decisions that are both faster and less accurate. The “higher” cortex is slower, but more exact.

A lizard (with its tiny, primordial brain) must often react quickly to danger. Instantaneously it jumps to avoid being eaten. It doesn’t matter exactly where it jumps (no accuracy called for)—it’s simply a case of immediately needing to exit the scene.

Back when we humans were dodging saber-toothed tigers, we also needed to react promptly. No time to think—just vamoose! Didn’t matter where—just outta there. But as we grew more secure and our lives became more complex, the need arose to make our decisions more carefully and precisely. Our longevity became better assured by slowing down, gathering the appropriate information, and becoming more meticulous in our judgments. The cortex grew, and then grew some more, to help us make those better choices. Thus evolution generated our big brain, so we could make those more deliberate, precise decisions. (This is contrary to the Bush administration’s mental throwback to more primitive times, when it made a quick decision to strike back, after 9/11, rather than pause and choose more wisely.)

Do we need two sites in our brain—with dissimilar and sometimes conflicting qualities—for decision making? We still have a few occasions when we need to make knee-jerk judgments. How well do the two locations communicate and cooperate with each other? Do they get into conflict with each other? Which one takes control in borderline cases? These are deeper questions for the experts; for which I won’t hazard an answer.

One fascinating behavior we exhibit, seemingly demonstrating that an inner conflict can occur, is when the sub-cortex (the fast acting one) grabs the initiative in a situation it regards as threatening, and makes the first choice. Before the cortex can get going on its deliberate analysis, the deed is done. Now, that precipitous decision is a blow to the ego, since it wants to believe that it’s in control of things. But while it was carefully pondering the situation, that damnable primitive sub-cortex stole the show. What’s a self-respecting ego to do? It’ll fib. It’ll make up a story about how it was planning to arrive at that decision anyway. In fact, it does very well—in its task of self-deception—of convincing us that it really was in charge. (Sound like Bush on Iraq?)

Clearly, we humans not yet fully evolved. There are more improvements needed in our brain functions. Where will we go next? Will we get these separate parts of our brain cooperating? Will we learn to avoid needlessly manufacturing threats, slow down, and grow an even bigger, wiser brain? Who knows? Tune in, in a million years or so (assuming we’re still around).