Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP
Posting-Version: version B 2.10.2 9/18/84; site psivax.UUCP
Path: utzoo!watmath!clyde!bonnie!akgua!sdcsvax!sdcrdcf!psivax!friesen
From: friesen@psivax.UUCP (Stanley Friesen)
Newsgroups: net.bio,net.origins,net.philosophy,net.sci,net.sf-lovers
Subject: Re: The missing step -- self-reproducing organisms
Message-ID: <134@psivax.UUCP>
Date: Wed, 14-Nov-84 18:16:12 EST
Article-I.D.: psivax.134
Posted: Wed Nov 14 18:16:12 1984
Date-Received: Fri, 16-Nov-84 07:04:44 EST
References: <241@hocsj.UUCP>
Organization: Pacesetter Systems Inc., Sylmar, CA
Lines: 55
Xref: sdcsvax net.bio:120 net.origins:523 net.philosophy:1139 net.sci:216 net.sf-lovers:4937

<>

> I have been giving some thought to the process of the first development
> of life and this morning I realized that I had been leaving out an
> important step.  I had been more or less thinking of it as a process
> with two major steps.  One is the creation of life from amino acids on a
> micro-level, the other is the evolution of that life into an intelligent
> being.  Both are very low probability events and each model must be
> repeated mega-many times before intelligent life can come about on a
> planet.

The evolution of "intelligent" life has little to do with "probability".
The prime controlling factor in evolution is *biological selection*
NOT chance, thus if the right combination of ecological circumstances
occurs then "intelligent" life WILL evolve. It is a recognized principle
of evolutionary science that similar circumstances produce similar
organisms.  Witness the similarity between the marsupial wolf and the
timber wolf, which are only distantly related; or the similarity between
the rat kangaroos and kangaroo rats. And it is a principle of ecological
science that similar climates produce similar ecologies, often with
completely different organisms.  Witness the occurance of "chaparral"
type scrublands in California, Chile, Southern Europe, and Southern
Australia, all with completely unique species of plants. Thus a planet
with a similar climatic history to Earth has a HIGH probability of
eventually evolving "intelligent" life.

> That was my thinking up to this morning.  Now it strikes me that I have
> been glossing over a pretty complex step, one which is likely to have a
> lower probability than either of the ones mentioned above.  That is the
> step of going from something that is merely alive to a self-reproducing
> (SR) cell.  This, it seems to me, is the biggest step of the three.

It is not a *seperate* step, most biologists consider self-reproduction
to be a necessary(but not sufficient) condition for life, thus
something that is not SR is not alive, by definition.

Thus instead of:
>     P(life forming)
>     P(new organism is SR given that it is alive)
>     P(SR, living organism evolves into an intelligent form of life)
we have:
	P(life forming)
	P(evolution of "intelligent") life)

Of these the first is very high, perhaps even 1.0 given a planet
with liquid water and a high carbon content in the atmosphere.
That is on the right sort of planet the formation of life may be
almost certain, due to the structure of the universe.
The second is probably somewhat lower because chance does play
a small role in evolution - because there is usually more than
one evolutionary solution to any given problem - BUT it is still
a fairly large probability.

					Sarima Noolendur
					sdcrdcf!psivax!friesen