Another theory about how life on Earth came to be. Specifically that it did not originate on this planet, but was introduced here through space debris, suggesting that somewhere out there, there is another atmosphere capable of sustaining life as we know it. Or at least, life as we knew it billions of years ago before we evolved form bacteria into our present selves.
It also suggests that life-forms are constantly being scattered through space to"take root" wherever possible.
As if it weren't bad enough to think that we were once apes, or paramecium...we could possible be space bacteria! I always thought this theory was interesting, since as humans we always think of ourselves as so superior. What if were all basically germs that thrived in an inviting environment and there zillions more like us all throughout the cosmos, all in different levels of evolution?