You now have an imaginary parallel line of people and chimps holding hands backwards in time - like a railway track with people and chimps lining each side.
You can now walk down the centre of these lines and look carefully at your mother's family line and the chimp's family line going back millions of years.
So what would our walker between the lines actually see? Can we tell the story back in time to the common ancestor in simple language but in enough detail for the walker to be able to research further?
Unfortunately, this illustration would never stand a chance with a creationist. He'll just tell you that the human line is going to consist only of humans back to the day of creation, and the chimp line is also going to consist of chimps and chimps only likewise to the day of creation. No common ancestor.
quote:Let's assume that you have a sister. You both have a common ancestor: your mother. Now let's say that you also have a cousin, whose mother is your mother's sister. You and your cousin also have a common ancestor: your grandmother on your mother's side. Everyone is related, but you have to go back two generations to find the common ancestor that you share with your cousin, but only one generation to find the one you share with your sister.
Good so far?
Now let's shoot forward in time a hundred years, three more generations down the line. Your great-granddaughter is unquestionably related to all three of you - yourself, your sister, and your cousin. She is directly related to you, and indirectly related to your sister and your cousin. She is more closely related to your sister than she is to your cousin, but she's still related nonetheless.
So if a paleontologist says that Ardi (or any other extinct hominid) may or may not be a direct ancestor to human beings, that isn't at all the same thing as saying that we're not related. In the example above, H. sapiens is your great-granddaughter. Ardi might be you, or he might be your cousin. Ardi might not be a direct ancestor, but he's still related. Our common ancestor is just further back in the lineage.
And there's the answer your primary assertion that the fact that there are no other hominids alive today proves that there never were any. Just because your sister didn't leave any children, that doesn't mean she never existed.
Your beliefs do not effect reality and evidently reality does not effect your beliefs. -Theodoric
Reality has a well-known liberal bias. -Steven Colbert
I never meant to say that the Conservatives are generally stupid. I meant to say that stupid people are generally Conservative. I believe that is so obviously and universally admitted a principle that I hardly think any gentleman will deny it. - John Stuart Mill