ecl@hocsj.UUCP (11/09/84)
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. Because of this, I find it highly unlikely that any two
intelligent races will ever meet in the universe. There may be more
than one intelligent, race but the probability of them being close
enough to find each other is very low, in my estimation. (Not to
mention the low probability that they would recognize each other as
intelligent.) The first step, I am told is not quite as amazing as I
thought because the constituents of life as we know it, the amino acids,
are more common than we may have thought in the past.
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 one thing for the amino acids to form something that in some abstract
sense is alive, it is quite another for this thing to be an SR organism.
I have never looked into the mathematics of SR automata, but my guess is
that it is pretty complex. In the evolution of life on a planet, it is
not sufficient that life come about, but also that it can outlive the
single organism. Even assuming that lightning strikes the right amino
acids and they start squirming, that is a long way from the organism
created actually being SR. Of the three probabilities:
P(life forming)
P(new organism is SR given that it is alive)
P(SR, living organism evolves into an intelligent form of life)
I judge the second to be the lowest. It is hard to judge the first
which seem almost mystical, but I can accept that it is a matter of
amino acids forming and adding electricity as was whimsically described
in the Julia Child Primordial Soup film some of you might have seen.
The tide of opinion in articles (and films) seems to be that it might
not be such a low probability event. I have come to accept that the
third probability is not all that low. Nobody talks much about it that
I have heard, but the second probability it seems to me could well be
the smallest of the three. Any comments?
[Incidentally, anyone wishing to build up brownie points with their
personal deity by claiming credit for Him/Her/It for having done it all,
you can send these comments to me directly by writing them into
/dev/null. I don't rule out the possibility, of course, but it all
comes down to faith and has little place in a scientific discussion.
Usually the arguments come down to say I should read what some person
said in a book rather than going out to nature and looking at the
evidence that the deity, if there is one, created with His/Her/Its own
hand. It is another whole farble, of course, but if someone believes in
a God, then they should believe the fossil record was created by that
God much more directly than any book ever printed.]
(Evelyn C. Leeper for)
Mark R. Leeper
...ihnp4!lznv!mrlprins@cornell.UUCP (Jan Prins) (11/10/84)
Evelyn/Mark Leeper write: > >[The] step of going from something that is merely alive to a self-reproducing >(SR) cell ... seems to me, is the biggest step of the three. It >is one thing for the amino acids to form something that in some abstract >sense is alive, it is quite another for this thing to be an SR organism. > This statement seems turned around to me. I find the creation of complex self- replicating molecules much less problematic than labelling them 'life-like'. Richard Dawkins feels 'survival of the fittest' can apply at a molecular level: If a large supply of 'parts' is available in the organic soup, then a simple self-replicating molecule (one that, in the presence of the right components incorporates them into one or more self-similar structures) will eventually become the most prevalent molecule in the soup. Unless, of course, there are several such molecules, in which case the 'fittest' (i.e. making use of more readily available parts, or having a higher probability of replication succes) will become the more numerous, by definition (the problem with these evolutionary theories is that they're dangerously close to being tautologies!). I take the sequence of events leading to ever-more complex self-replicating structures to be not unplausible. That it should proceed inexorably in the direction of 'intelligence' I find more unlikely and mysterious. "We started small" cornell!prins
lab@qubix.UUCP (Q-Bick) (11/12/84)
An excellent book on this is A.E. Wilder Smith's _The Natural Sciences
Know Nothing of Evolution_. He discusses the problem in detail**2. (I.e.
he concentrates on the key points and works them to death.) It can be
understood with an elementary background in biology and chemistry,
although *really appreciating* would require a background in organic
chemistry (more than what I have).
--
The Ice Floe of Larry Bickford
{amd,decwrl,sun,idi,ittvax}!qubix!lab
You can't settle the issue until you've settled how to settle the issue.carter@gatech.UUCP (Carter Bullard) (11/13/84)
Indeed, it is an extremely complex thing. However, the probability of
complex living organisms evolving ( coming into existence ) is actually very
high, say 1, since it has occured, for whatever reason.
--
Carter Bullard
ICS, Georgia Institute of Technology, Atlanta GA 30332
CSNet:Carter @ Gatech ARPA:Carter.Gatech @ CSNet-relay.arpa
uucp:...!{akgua,allegra,amd,ihnp4,hplabs,seismo,ut-ngp}!gatech!carterwapd@houxj.UUCP (Bill Dietrich) (11/14/84)
Is the mechanism of DNA/RNA reproduction understood well enough that someone could create other molecules with similar reproduction abilities ? Has someone at least determined that similar molecules can be built from other elements ? I assume that actually building such a big molecule from scratch is beyond present-day capabilities. Bill Dietrich houxj!wapd
chuck@dartvax.UUCP (Chuck Simmons) (11/14/84)
<mexican jumping bean --> (-:) > > Indeed, it is an extremely complex thing. However, the probability of > complex living organisms evolving ( coming into existence ) is actually very > high, say 1, since it has occured, for whatever reason. > > Carter Bullard Perhaps, then, we should ask "what percentage of solar systems in the universe (galaxy/within 500 light years of our sun/etc) will develop 'complex living organisms' (whatever *they* are)?" Now and then I hear estimates from people like Carl Sagan and people who enjoy speculating about UFO's suggesting that the galaxy is teeming with intelligent life. I always wonder where these estimates come from. How do experts decide whether or not a star is capable of supporting life? (And not just life but 'interesting life'.) How close to the star does a planet have to be to support life? How far away? Do you need the planet? How likely is it that a planet is in this range? What sort of an atmosphere does the planet need? Is an oversize moon necessary? Unfortunately, I think we will only be able to guess at these answers until we meet our first alien civilization, and I don't see that happening in the forseeable future. By the by... I hear rumours that some secret government agency has actually found pieces of a wrecked spaceship and alien bodies and everything! I don't suppose any of you out there in netland work for this government agency and would like to spill some beans? (:-) dartvax!chuck
lambert@mcvax.UUCP (Lambert Meertens) (11/14/84)
: > Indeed, it is an extremely complex thing. However, the probability of > complex living organisms evolving ( coming into existence ) is actually very > high, say 1, since it has occured, for whatever reason. The probability of a continent coming into existence, shaped exactly like North-America, is very high too, since it HAS occurred, for whatever reason. The probability of such a continent existing elsewhere in the universe (especially if we define the Twin Towers etc. to be part of the shape) is not that high. If life on Earth counts, the probability of living organisms having evolved is 1 and not less. If we try to estimate the probability of life evolving elsewhere, the information that it happened here (once) does not increase that probability one bit. Lambert Meertens ...!{seismo,philabs,decvax}!lambert@mcvax.UUCP CWI (Centre for Mathematics and Computer Science), Amsterdam -- Lambert Meertens ...!{seismo,philabs,decvax}!lambert@mcvax.UUCP CWI (Centre for Mathematics and Computer Science), Amsterdam
friesen@psivax.UUCP (Stanley Friesen) (11/15/84)
<> > 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
johnston@spp1.UUCP (11/15/84)
> Indeed, it is an extremely complex thing. However, the probability of > complex living organisms evolving ( coming into existence ) is actually very > high, say 1, since it has occured, for whatever reason. > > -- > Carter Bullard I don't know what to say exactly to this statement. Am I missing some logic link or can you really state the probability of something coming into existence by a certain method soley on the fact it is in existence? I guess I can now advance my pet theory about the grand canyon coming into existence by a prehistoric giant urinating on arizona because, indeed, the grand canyon exists. Mike Johnston
jfw@mit-eddie.UUCP (John Woods) (11/16/84)
A.E.Wilder-Smith -- I watched him and Dr. Jerome Lettvin debate at MIT some time ago. Dr. Philip Morrison was the moderator. Dr. Wilder-Smith made several statements which incoming MIT Freshlings not majoring in biology or chemistry know better than to make, regarding those topics. If his book is more of what I saw in that debate, I would not use the book for wrapping fish with. -- John Woods, Charles River Data Systems decvax!frog!john, mit-eddie!jfw, JFW%mit-ccc@MIT-XX When your puppy goes off in another room, is it because of the explosive charge?
mmt@dciem.UUCP (Martin Taylor) (11/20/84)
==============
Is the mechanism of DNA/RNA reproduction understood well
enough that someone could create other molecules with
similar reproduction abilities ? Has someone at least
determined that similar molecules can be built from other
elements ? I assume that actually building such a big
molecule from scratch is beyond present-day capabilities.
==============
Logically, it isn't necessary that molecules reproduce themselves.
What is required is that in their presence (or presence in the recent
past) the likelihood of finding another such molecule increases.
Surface catalysis might lead to such conditions. Imagine a scenario
involving something rather like a crystal (viruses can form crystals,
so they are not limited to just non-living material). On this surface
molecules of another kind can form by selective adsorption or some
such mechanism. These other molecules can themselves seed new crystals.
Or again, think of the clay-surface catalysis that has been proposed
for construction of complex molecules. If there happened to develop
a molecule whose presence on the surface slightly improved the catalysis
for making more of the same, the result would be sufficient to permit
evolution of better self-replicating systems.
Whatever happened, it's a pretty good bet that catalysis of one kind
or another was involved.
--
Martin Taylor
{allegra,linus,ihnp4,floyd,ubc-vision}!utzoo!dciem!mmt
{uw-beaver,qucis,watmath}!utcsrgv!dciem!mmt