Once upon a time, the captain and crew of timeship Ouroboros flew back 4.5 billion years in search of the origin of life. After shuttling back and forth in time, they found an era just between pre-life and life.
The time travelers landed at the shore of a milky iridescendent sea. They sent out robots to take samples; these showed that the sea’s chemistry quivered on the verge of life.
The captain and crew of the timeship celebrated with a feast from ship’s supplies. But some of the food was not the best, and they all felt intestinal distress. They lined up to use the head, and the plumbing threatened to overflow; so the captain ordered an emergency purge of the septic tanks.
By next morning the sea changed. Its rainbow opalescence turned to dark brown. Samples showed that captain and crew’s E. Coli were multiplying and mutating in their new environment. It was too late to contain the contamination; ocean currents had already dispersed their intestinal bacteria for hundreds of kilometers.
They lifted off and skipped futureward. Their instruments showed the global spread of life from the infection point.
The captain said, “How am I to explain this, in my report?”
The chief scientist said, “That life caused itself. Our time-ship was part of a time-cycle. Biology is full of strange loops.”
The mechanic said, “I blame the burritos.”
Moral: A circle has no beginning.