I would argue that masturbation is the human animal's most important adaptation. The very cornerstone of our technological civilization. Our hands evolved to grip tools, all right—including our own. You see, thinkers, inventors, and scientists are usually geeks, and geeks have a harder time getting laid than anyone. Without the built-in sexual release valve provided by masturbation, it's doubtful that early humans would have ever mastered the secrets of fire or discovered the wheel. And you can bet that Galileo, Newton, and Einstein never would have made their discoveries if they hadn't first been able to clear their heads by slapping the salami (or "knocking a few protons off the old hydrogen atom"). The same goes for Marie Curie. Before she discovered radium, you can be certain she first discovered the little man in the canoe.