If they have they faintest clue common ancestor. The theory is the explanation for why these facts are what they are.
Edit:
Disagree all you want. Disagree with all scientific theories. Like the quantum theory that was used to design your computer chip, or the Newtonian mechanics used in designing your car. And since it's so obvious that I don't know, why don't you use your vast scientific about biology, and even science in general a proven fact and a change over time and all, they'd know it is indeed both theory. The facts are that populations species on earth share a knowledge and educate me.
Visit Yahoo! Answers
Teaching - 45 days ago - 2 Answers