> Is it possible that while the protein protocells may be alive, they are not
> the way life began on earth? IOW, they are not the common ancestor of all
> life.
>
That is very possible; even Fox had admitted this possibility, though not
within this last decade.
>
> If this is so, then we haven't truly achieved the goal of repeating by
> experimentation what happened at the dawn of life.
>
As I said, that is certainly possible. However, it should be pointed out
that Fox's proteinoid microsphere protocell (fPMP) scenario is virtually the
only one that is based nearly entirely on experimentation rather than being a
theoretical construct for which some or no experimentation has been done. In
other words, scenarios like hypercycles, clay matrices, random replicators
and the like are currently purely theoretical with little or no experimental
support, whereas fPMP scenario is almost entirely based on experimentation
with no prior theoretical construct to suggest that it might be true. I
should also point out that, of all the possible scenarios for the origin of
life on earth, fPMP scenario is the only one that has led directly to the
synthesis of living cells in the lab. Not even the RNA-world scenario can
boast that accomplishment.
>
> Also, why must we pick one scenario over another? Why not a combination of
> say, random replicators, clay, and protenoids?
>
I have argued much the same myself, and in fact fPMPs could help out these
other scenarios by bridging gaps they cannot otherwise account for. You see,
fPMPs have the advantage over every other scenario of being able to provide a
continuous sequence of events from simple chemicals to precusor biomolecules
to macromolecules to living cells. The other scenarios either rely on the
pre-existence of macromolecules with no explanation for how these
macromolecules formed or explain the formation of macromolecules but have no
explanation for the self-assembly of these macromolecules into living cells.
fPMPs not only can bridge these gaps, they also provide the basic cellular
structure into which can be incorporated amphiphilic lipids, RNA molecules
and true enzymes that might have been abiotically synthesized by other
mechanisms. In other words, they would provide the perfect haven that could
protect more advanced, but more vulnerable, macromolecules and
metabolic/genetic systems as they struggled to evolve.
Kevin L. O'Brien