I don't believe it but it is quite interesting to think about.. What if we are aliens. Humans lived on a planet not in this galaxy that was hospitable and we were an advanced race(had space travel etc.) but the planet we lived on was going to become inhospitable (climate change, death of a sun, etc.) so we got on ships and found a hospitable planet (earth) and now we are here. Discuss theories that make you start thinking.