[meteorite-list] THE ODDS OF LIFE

From: Sterling K. Webb <kelly_at_meteoritecentral.com>
Date: Tue Jul 19 19:05:25 2005
Message-ID: <42DD870F.77A4B0F8_at_bhil.com>

Everybody!

    Probabilities are tricky things. When they're imponderable, they
just can not be estimated, except by guess and golly. Doug draws one
conclusion from 100 bacteria. Marc draws the opposite. As for the
mathematical odds of either one's case, it's like whether you like
broccoli or not, imponderable and a matter of individual taste.

    For example, since all of you are alive, you probably think that the
odds of life itself are reasonable. Well. that's a mere prejudice. Oh,
tell me about the primordial soup and the inevitability of life...

    Let's cook up the minimum amount of DNA to a have a self-replicating
strand, or about 600 bases. That isn't very much DNA. A very primitive
virus might have 170,000 bases. A bacteria has 7,000,000 bases. You
yourself have got 6,000,000,000 bases. No, 600 bases is easy, right?

    In information theory, the meaningfulness of a message is
interpreted as the level of probability of the message, or the inverse
of the odds that the data was generated randomly. It depends on the
number of bits. What are those odds?

    Say you want to send a simple message: SEE SPOT RUN. Why not
generate it randomly using the minimum character set. The odds are: 6.1
times 10 to the 23rd power to one.

    Get yourself a PC, program it to create sets of 13 random character
strings at the rate of 10,000,000 sets per SECOND. Come back in about
two billion years and pick up the printout. (Bring help; it's heavy.)

    Isn't it lucky that the alphabet of DNA is so much simpler? Only 4
characters (the bases), so the odds against the random creation of a 600
basepair string is "only" 4 to the 600th power to one. That's 10 to the
360th power to one.

    That's 1, followed by...
000,000,000,000,000,000,000,000,000,000,000,
000,000,000,000,000,000,000,000,000,000,000,
000,000,000,000,000,000,000,000,000,000,000,
000,000,000,000,000,000,000,000,000,000,000,
000,000,000,000,000,000,000,000,000,000,000,
000,000,000,000,000,000,000,000,000,000,000,
000,000,000,000,000,000,000,000,000,000,000,
000,000,000,000,000,000,000,000,000,000,000,
000,000,000,000,000,000,000,000,000,000,000,
000,000,000,000,000,000,000,000,000,000,000

    In words, you want it in words? That's ten nonillion nonillion
googol googol googol to one... against.

    Still with me? Don't think about that number up there too much or
too hard. It won't get any easier and eventually, your brain will turn
to goo.

    Let's make it easy for Life.

    OK, the oceans of the early Earth had no more than 10 to the 44th
power carbon atoms. Let's say they're ALL in nucleic acids already. I
said I'd make it easy. To make it even easier, let's say all those bases
are already assembled into ten basepair chunks. Let them react with each
other at the rate of 100 reactions per second. Instant life, right?

    Wrong. It would take 10 to the 309th power years for it to happen.
The universe won't last that long. Wait! The universe could already be
that old; the wait it over; it's finally happened.

    Wrong. The universe is datable and young.

    What's wrong here?

    OK, OK, let's say EVERY star in EVERY galaxy in the ENTIRE universe
has an Earth-like planet with oceans of organic nucleic acid sludge, all
working overtime to churn out Life. That's 4 times 10 to the 42th power
planets. Does it help?

    No. Not a bit. Well, a little. It still takes 2.5 times 10 to the
266th power years to produce Life. Forget it about it.

    Life is IMPOSSIBLE. It can't exist. There is NO life. All of you out
there, the ones who think you are alive, you're delusional. You're a
figment of your own imaginations. Why am I even talking to you? Go see a
therapist. You have a problem.

    From this, some people conclude that our little insignificant planet
contains the ONLY life anywhere in the universe. We're it. We're all
there is. It's a fluke, never to be repeated. The universe is a desolate
wasteland of dead rocks, frozen gases, exploding stars, and inorganic
worlds: a collection of 100,000 billion billion chunks of dead matter
and wonderful US.

    Panspermia, life elsewhere that is delivered to the Earth, just
moves the problem further away but doesn't help the odds much, as we saw
above.

    If we're all there is, I feel uneasy about it. Honestly, I don't
want the responsibility. If we humans are all the intelligent Life there
is, the universe is in deep trouble. If we divvy up the responsibility
for the universe among six billion people, then I'm responsible for
roughly 10 to the 34th power planets! Sheesh! I don't even have a pet...

    But, if that's true, life should never have happened at all, not on
Earth, not anywhere. The odds are really against it. 10 to the 312th
power to one against it happening in the first billion years on Earth.
The notion that we're the only life in the universe is even more
unlikely, in a purely human sense, than the idea that we're not.

    The only thing panspermia has going for it is that it is possible
that somewhere, once, there was a spot where the odds were not stacked
so relentlessly against Life.

    What's wrong with this picture?

    The argument is flawed, obviously. I just thumped myself all over --
ouch! -- and I conclude that I am actually alive, odds or no odds. And,
I can't find the deeds to those 10 to the 34th power planets. Why is
this conclusive and irrefutable mathematical argument dead wrong?

    What is DNA?

    DNA is a recording medium. It's not life. It functions just like
writing, or better still, just like the hard drive in your computer. It
stores instructions and when needed, executes them later. Any recording
mechanism will do, with varying degrees of speed and efficiency. It
could be a paper tape punched with holes, plastic audio tape, floppy
disks, a hard drive, CD's -- anything! Even DNA.

    So, calculating the odds against the random production of DNA is
like asking for the odds of the spontaneous random creation of a CD! And
a self-copying CD, at that! (Can I get those at Target?) Not very
likely. And NOT to the point.

    Life is not DNA. And DNA is not life. DNA is an aperiodic crystal.
Big deal. BEFORE there was DNA, there was life. Don't ask me what it was
like, 'cause I don't know. Nobody does. My guess? Material distinct from
the outside environment, enclosed in a membrane that interacted with
materials in the environment. Minimal definition.

    Beings of some kind "lived" and "died." They may have replicated
themselves by a very primitive partition of contents and membrane, but
maybe not. They may merely have been created and destroyed and created
and destroyed. Their membranes co-opted exterior materials to facilitate
interaction, helplessly, in a template fashion.

    The molecules on the membrane may have been crowded and combined
with each other, merely by molecular attraction. It may have grown so
crowded on the membrane that some creatures took some of the interaction
molecules inside their membrane where they could react with interior
molecules as well.

    The interior molecules may have had replicational reactions with the
interaction molecules, and well, you get the drift... Eventually,
something like DNA accumulated by being used for "recording." Maybe it
wasn't self-duplicating yet. Maybe certain other molecules triggered the
duplication of small strings. Maybe DNA was useful in some way before it
was big enough to self-duplicate.

    But, at some point, fast reproduction instead of slow replication
became possible. Maybe these were forms so primitive they didn't need
600 bases. (The so-called nano-bacteria, like those "found" in the
Martian meteorite and certain Earthly environments, have room inside
them for only 10 to maybe 100 bases, which is the real reason so many
folks don't believe in them.)

    But, any critter that can pull off this reproductive trick would
have spread and multiplied so fast that it would have wiped out all its
non-DNA competition, and pre-DNA or non-DNA life vanished from the
Earth, the greatest mass extinction ever.

    The key has to be that the creation of life was NOT a random
process. For every molecule that fits a template, millions did not.
That's a selective mechanism, not a random one. If you allow a strong
selective effect at every step instead of random chance, it's done in
short order, IF there is a preferred pathway.

    Carbon is the only element that forms so many countless varied
compounds. We know of tens of millions; likely there are many billions
possible, more? Is there a preferred pathway there, one hundred
selective jumps to life? One thousand? One million? We can do that.
Selection is known to be essential in life since DNA, fellah named
Darwin, I b'lieve. Why not before DNA? Life could simply be inherent in
the carbon atom. Good planning, say I.

    We really understand, and that only to a limited degree, the history
of life for the last 600 million years of our planet. There is a murky
to non-existent fossil record for the 4 billion years before then, and
confusion abounds before the great leap forward to that highly advanced
metazoan ancestor of us all, the sponge.

    If the odds against any Life at all anywhere are so... astronomical,
then to find any indisputable evidence of life anywhere else in our
solar system would carry a powerful implication of life elsewhere in the
universe that would be overwhelming, particularly if that other life
were distinct from Earthly life. That would cinch it.

    I'm waiting.


Sterling K. Webb
Received on Tue 19 Jul 2005 07:04:48 PM PDT