We could have existed before…

Okay, I just finished watching this show on the history channel called "The World after Humans" or something like that. It was all about what would happen to the world if humans suddenly ceased to exist. It was very interesting because in today's world that it is a definite possibility that humanity could become extinct from war, disease, pollution, or something else. In the show they showed what happened to the world after different lengths of time and by 10,000 years after humans there were no remnants left of humanity at all except maybe the pyramids or Mount Rushmore but they would be buried under sand or vegetation. The other thing that was interesting was that they said that if you looked at the entire time the Earth has existed, which is something around 5 or 6 billion years, as one day then the time that humans have been around would only be about 30 seconds. That is crazy!!! So if you were really imaginative you could say that perhaps other civilizations existed long before humanity and they all perished like we did and now we have no record of them because nature took everything back. Maybe there were civilizations before us that became more advanced then we are today.