Alien populations on earth

I just wondered how many people are called earthlings really are human? what percentages are actually truely human race. I read a thread else where and they said that it is afrikans who are the original race on earth. All other members of the planet are indeed alien in nature. I am not sure how many types of aliens are on the earth, and it makes me wonder if they will come back after 2012 to take back their own? would people accept that they came from the origins of the stars? matt