meaning of common words

[Tom DiBenedetto]

On Mon, 16 Jun 1997 15:51:41 -0400, Rodham E. Tulloss wrote:

>By the common meaning of the word ancestor, it is not uncommon for
>an offspring and an ancestor to be alive simultaneously.  For example,
>my father, myself, my two sons.  The latter three people having contemporaneous
>ancestors.  I think that tdib is using a specialized meaning of the term
>ancestor.  Others in the present discussion are not.

An offspring and its ancestor can be alive simultaneously because the
term ancestor merely refers to the relationship between them. If a
peripheral isolate is considered a descendant of some population (we
all seem to agree on that), then why isnt the larger unchanged
population also seen as a descendant of the same population? Merely
because it hasnt evolved a diagnostic character which can serve as
*evidence* of that relationship? For once it does evolve such a
character, we would all agree it is a descendant, and not the
ancestor of the isolate, right? Is there anything different between
the *historical relationships* between the "old" population and the
isolate vs. "old" pop and the contemporary large unchanged
population? I dont see any.
        The better example, although a bit wierd, would refer to a
case where a clone of my father would have been produced at the same
time as I was born. Would the clone be my ancestor? Or would both the
clone and I be descendants of my father even though you couldnt
distinguish the clone from my father on the basis of character
evidence?