The Farmy Paradox of Spacefaring Species

Space is full of tiny particles called cosmic dust, the raw material that planets are made from. Cosmic dust would pose a hazard to any space craft travelling at some significant fraction of the speed of light. At these speeds, the spacecraft's connectic energy is so unimaginably huge that a collision with even some tiny piece of matter would be catastrophic. The need for scarce resources appears to be one of the few universal commonalities that any civilization will have to deal with. This means that we can pretty confidently use this clue to predict the behavior of any intelligent life.