Text 609, 103 rader
Skriven 2004-11-01 16:35:00 av Tinyurl.Com/uh3t (1:278/230)
Ärende: Re: Metabolism Forced
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"TomHendricks474" <tomhendricks474@cs.com> previously wrote:
>> So you agree that before the first replicator
>> there was a type of chemical replication going on.

That doesn't make sense to me. A replicator is something which
replicates. If replication was going on, then there was a replicator
doing it. Apparently you don't define the word "replicator" to mean
something that replicates, so please explain why you say something was
replicating but it wasn't a replicator.

My current belief is that simple chemical replication, such as some
sort of catalytic cycle/loop, was the first kind of replication going
on. Whatever chemical(s) was/were replicating themselves is what
I would call the first replicator. (That replicator consists of *all*
the catalysts in that cycle/loop, considered as a unit, since any one
by itself catalyzes the production of all the others and itself, so
which one you consider the starting point of the cycle/loop is
irrelevant.)

> From: Brett Aubrey <brett.aubrey@shaw.ca>

> I think there's a chance that there can be chemical replicators.
> And I think if there was, the chances that life "emerged" or "was
> forced" out of them is far more remote than some other process
> (unknown to me) where there was no chemical replication going on.
> This is because I think that 2 rare, complex and overlapping events
> (replication, then life) are less likely than 1 (life, which learns
> how to replicate, as we know it did).

I disagree. Once a simple chemical replicator takes hold of the
chemistry of the ocean, basically dominating it, it's relatively simple
for that to eventually evolve, perhaps by getting slightly modified or
combined with other chemicals, perhaps by inducing a parasitical
replicator which replaces the original. But for a fully-formed lifeform
to suddenly emerge out of nothing, rather than evolve from a simple
chemical replicator, is so unlikely as to be virtually impossible.

So the comparison is between one rare chemical event followed by
evolution all the way to life as we know it today, vs. an impossibly
unlikely direct formation of life as we know it today.

>> Was there also a type of 'chemical selection"
>> I tend to think that there was in the loosest sense
>> of hte word.
> Possibly, but doubtful that a replicating one that led to life.

Several months ago we discussed some mechanisms by which simple
chemical replicators might form colonies/ecosystems on lipid or other
bubbles, how they might combine with various metal ions to form
variants, how natural selection might occur among individual
replicators and/or bubble-ecosystems viewed as genomes, how single
peptides mibht become involved, how doubling of strand-length of
replicators might produce longer and longer polypeptides, and how these
might lead to life as we know it. Do you consider none of that even
remotely possible?

> Do you disagree that you and I for instance, exist as living beings
> because of a "spark of life"?

I don't know his opinion, but in my opinion that's hogwash. There's no
such thing as a "spark" which determines whether something is alive or
dead. In fact there's no clear line between living and not living. When
a living thing starts dying, it goes through several stages. In a
multi-cellular being such as a human, largescale body functions such as
blood flow stop, which causes the individual cells to experience stress
from lack of oxygen, although they are still individually alive, just
not happy campers. Then the cells themselves run out of oxygen and
cease generating ATP, and then they run out of ATP and cease performing
essential life processes such as repair of DNA and production of
proteins to replace those which are breaking down all the time. At some
point so many of the chemicals have broken down that even if oxygen
were to be supplied again the cell couldn't get going again without
extensive help, the cellular equivalent of life-support, which doesn't
exist with today's technology but could at some future time. (The
fictional StarTrek series envisioned medical treatment to repair cell
damage and get "dead" cells back to functionning again. I see no reason
why such technology might not someday be developed.)

> at some point you surely must admit that there was likely no life on
> the planet, while at another point, there was?  This seems a
> no-brainer to me but you keep fighting it(?).

It's a no-brainer to you because you don't use your brain properly. At
some point there was no replication going on at all, and all of us
would agree there was no life. Currently almost all of us agree there's
lots of life, and there has been for a very long time (6,000 years
according to YECs, 3,500,000,000 years according to most of us).
Sometime between the definitely-no-life and definitely-life time there
were times when primitive replicators existed, which we can't agree
whether to consider life or not-life-yet. There probably was a rather
long time, hundreds of millions of years, during which the question of
life or not-life depends on definition, and it's not appropriate to pin
down some particular point before which there was no life and after
which there was life.
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