SETI and the Evolution of Intelligence (or, Doom and Gloom of the Day)

Anyone familiar with SETI? That is, the Search for Extraterrestrial Intelligence? The goal of the program is to detect radio signals from intelligent beings elsewhere in the universe. But no signals have ever been found. This is odd, considering our assumption that the universe was teeming with life, and therefore must be teeming with intelligent species, many of which would have discovered radio at some point. But there's been nothing.

This suggests two or three possibilities--the less interesting ones are that our instruments aren't powerful enough, or that the radio signals are too weak or distorted by distance to be detected. Or some other dull, technical reason. The more interesting (and scary) possibility is that maybe intelligent races aren't common at all. This leads to the question, "Why?"

My own theory is that "intelligence" is an evolutionary advantage, but only up to a point. Natural selection ends up selecting for ever-increasing intelligence, until a point is reached when one species is intelligent enough to think it can bend the ecosystem to its own will. But it really can't--inevitably, this supposedly intellgent species will use everything up in a vast population explosion. Intelligence, to the degree possessed by humanity, just may be an evolutionary dead end. Races that possess it are capable of ruining their planets more quickly than evolutionary processes can evolve a race intelligent enough to not ruin the world. This, of course, is where the human race now stands--we are on the verge of ruining the world, and the next evolutionary step is no where in sight. In fact, the problem really is that evolution only reponds after a disaster--the organisms that were lucky enough to survive, for whatever reason, become the new species, and whatever characteristics allowed them to survive become the new, defining characteristics of the new species.

It would be really interesting to see how this turns out--after the big die-off, will the human race that's left over be substantially smarter than it is now? Or substantially stupider? Will the quality of our intelligence have changed in some fundamental way? Will the new race be much more geared towards selfish individualism (albeit on a smaller scale, since all the large scale stuff will no longer be possible), or will we be an even more socially conscious species than we are now? Will humans evolve into a species with hivelike social rigidity?

My money is on the latter, since I have a difficult time seeing any big evolutionary advantage to individualism--termites and ants do remarkably well. However, given a large cataclysm, all bets are pretty much off.