hmm.....i too agree with the alien theory, but now that i think about, something doesn't make sense.....ok, i do not believe in the idea that aliens immigrated from mars because A) why have we not been able to locate their vessels (or have we, and the governement hid them);

speaking in terms of immigration, what about dinosoars? were aliens dino-like beings, which evolved into ignoratn species.....for it is evident that before humans, creatures were not as intelligent.....
i would rather assume that the aliens, being highly intelligent, discovered a way to "plant" life on our planet, (perhaps corresponding to their very own) where we then evolved much like they did, but with different, yet similar species.....such as, perhaps we are a form of what the aliens were, and animals such as a dog is very much like an animal they once had, but the difference is is that perhaps our dogs could be more docile than theirs....