<< BV>In which case, one common ancestor would be obvious. If on
BV>the other hand, life is the inevitable result of
BV>complexity, as Stuart Kauffman suggests, or as Michael
BV>Denton appears to believe, life is a natural phenomenon in
BV>the universe, life must have arisen many times. In that
BV>case one common ancestor (or even 3) would hardly be
BV>likely, would it?
Wesley:
>Life can commonly arise without the necessity that it commonly
>arise many times *in the same ecosystem*. The scenario
>described conforms to a "winner-take-all" situation. Chemical
>resources would exist prior to the first self-replicating
>system that would thereafter be sequestered in instances of
>that self-replicator. While not an absolute bar to further
>novel self-replicating systems, it would certainly reduce the
>likelihood of further ones arising.
But there is no reason to think there should only be one ecosystem.
If a self-replicating system arose, I agree this would decrease the
likelihood of another self-replicating system arising *IF* the original
uses the resources needed to generate the other. But this doesn't
effect *different* life forms from arising. For example, supposedly a
self-replicating system arose that uses L-amino acids. Why didn't one arise
that uses D-amino acids? The self-replicating system that uses L
would not take anything away from the environment that would prevent
the appearance of a D-life-form. What's more, life uses only a small
subset of all possible amino acids (only 20; and some of these are
thought to have been acquired into life after its appearance). Given
that abiogenesis experiments produce many other kinds of amino
acids not used by life (often in greater concentrations), why didn't
a life form appear that used these amino acids? The bottom line is
that there would be lots and lots of leftovers after the "winner takes all."
Mike