[asa] Out of Africa? (DNA studies to find the first humans)

        Hi all- a question for something I don't understand. I hear of
DNA studies to determine where humans originated (out of Africa, etc.).
But how could that be determined since we don't even know what a 'human'
is? Seems like the quest assumes there is some sort of DNA line where
you have a non-human, then a human. Seems to me like evolution says
change is gradual- no dividing line.

        For example, apes have one more pair of chromosomes than human.
Two ape chromosomes fused to make 1 human chromosome (human chromosome
number 2, I believe). Therefore, at some point an animal existed that
had these chromosomes fused. Is that a human at that point? What does
it take to be human? How can DNA studies find a "first human" if we
don't even know what that looks like?

        A short answer would be fine. I won't be able to read any
references to books- already have a backlog of books to read.

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Received on Thu Jun 19 16:27:54 2008