Have you heard the theory that certain building blocks of life made it to Earth via comets and the like?
For today's off-the-wall question, this is the starting off point. Assume that what grew into life was seeded by various comets, asteroids, meteorites, and other space debris. Okay, then...
What if that space debris was seeded by another civilization as a way to explore other worlds that those beings couldn't get to?
(I'm turning off Through the Wormhole now...)