[ExI] Chemical Origins of Life (was Re: Panbiogenesis)

[Kelly Anderson]

On Fri, Jan 27, 2012 at 5:29 AM, The Avantguardian
<avantguardian2020 at yahoo.com> wrote:
> The biogenesis people say that is because conditions on early earth were different.
> That is fine. But we can simulate early earth chemically in a lab. We get organics but
> not life, not yet, *not once*, not after decades of trying.

This is an extraordinary statement. It's the kind of stuff I read in
second rate Creationist literature. I expect better of this list.
Let's dive into the details for a bit. I've been studying this subject
fairly deeply for about the last two months, so this is pretty fresh.
I'm not exactly an expert, but I'm trying to learn what I can about
the chemical origins of life. If I make any mistakes in this posting,
hopefully they'll get corrected.

First off, simulating RELEVANT environments of the early earth in the
lab is extraordinarily difficult. Three of the environments in which
early chemical evolution (pre RNA stuff that must have occurred) is
hypothesized to have possibly happened are hydrothermal vents at the
ocean floor,  and/or deep within the crust of the earth assisted by
minerals and/or inside crystalline structures in clay. (There are
other hypothesis, but these three give a flavor for how diverse
current lines of thinking are and how hard it is to follow the
evidence or reproduce results in the lab.)

Some simple steps may have occurred in deep space, which is equally
difficult to simulate in lab conditions. The best vacuum we can
produce is a thousand times as dense as the typical patch of space in
a "dense" interstellar cloud. (Only an astronomer would consider a
vacuum of this quality a "dense" cloud... LOL)

Just simulating the pressures of the ocean floor or deep within the
earth's crust in the lab is extraordinarily difficult. Keeping those
pressures up for a long period of time is impossible. Keeping it up
for the millions of years that the early earth had to work with (and
needed) is obviously impractical. Doing so in the presence of the
right minerals requires knowing what those would be, and we have no
idea what those might be (if indeed minerals played an important roll
at all -- but they probably did).

Many simpler elements of life have been synthesized in the lab, such
as most amino acids, lipids and simple cellular wall structures that
are made of lipids, and a few other things have been synthesized in
enough different ways that there is no doubt the early earth was full
of these simple chemicals.

There is a great hole in our understanding between these simple
chemicals and replicative chemical systems with the hereditary memory
and possibility of mutation that is required to get to life. But it
seems very highly likely due to the situation on the surface of the
earth at the time (Hadean Eon -- meteor and comet bombardment, bad for
life on the surface) that whatever happened happened at very high
temperatures and pressures. (This seems especially likely since life
evolved in the first 100,000,000 years after the surface became
semi-habitable, which was pretty darn fast in those days.) There are
only a very small number of labs that can simulate these conditions.
Robert Hazen's (Genesis - The Scientific Quest for Life's Origin)
telling of his experiments at 2,000 atmospheres and 250 degrees C with
pyruvate welded into gold capsules the size of a grain of rice are
harrowing. This is NOT easy stuff to do, even with the most competent
help in the world and lots of NASA money.

Similarly, we do not have good enough computer simulations to
determine what might go on chemically in such circumstances that way.
We can't even fold protein with computers without using supercomputers
or distributed mesh computing.

In addition, we have no equipment capable of sorting out the kinds of
replicative emergent games that are going on inside of clay. We just
barely got DNA sequencing machines, and we KNOW that's important.
There is no equipment that can analyze the crystals in clay at the
level that would be required to truly follow that line of questioning.

The production of life from chemicals is FAR too large a jump to have
happened in one jump. There MUST have been an evolutionary system
prior to RNA to jump start the system. But we have no clear idea of
what that system might have looked like. Did it involve minerals deep
in the earth's crust at high temperature and pressure? Who knows? But
it might have. Or it may have been a small part of an extremely
complex and unlikely set of circumstances occurring in a number of
environments.

Am I saying that Panbiogenesis is impossible? No, that's just another
of a group of interesting theories floating around out there (joke
intended)...

Mr. Hazen's book is very interesting. And it points out that we are
just about as clueless about the chemical origins of life as Newton
was about Quantum Mechanics. I believe science will eventually figure
it out.

However, to criticize the current scientific community for not yet
producing life in the lab the same way as it came about on the early
earth plays into the hands of eager creationists and is grossly naive.

A hydrogen atom is approximately 2.5 x 10^-11 meters (25 pm) in diameter.
A water molecule is approximately 280 pm across.
A cell membrane is 10 nm thick
A clay particle is about 10^-6 m (micrometer) across. (you can see why
figuring out their crystaline structure is hard)
A typical Prokaryotic Cell is 250 micrometers across.
See http://htwins.net/scale/

According to some estimates, there are about 12,000,000,000 atoms in a
simple bacteria. Many of these are water, but a vast number of these
cells are doing their job within highly complex structures.

A simple amino acid like Lysine has 24 atoms. Constructing Lysine in
the lab is easy. Constructing life is considerably harder.

Take for example a virus. A typical virus contains around 600,000,000
atoms (http://answers.yahoo.com/question/index?qid=20060826150954AASGjhh)
ALL of which are involved in it's structure. A virus can't even do
it's own metabolism, it has to hijack the metabolism of a real cell to
reproduce.

The point here is that getting from organic chemicals with less than
100 atoms (which is what has been produced in Stanley Miller type
experiments). Or lipids with a molecular weight around 2000* to
something with around 1,000,000,000 atoms, which would likely be the
size of the simplest theoretically functional cell... is an extreme
jump that requires some kind of emergent, evolutionary process. Or
God. And I don't think science has had enough time to work on the
problem to jump immediately to the God hypothesis.

Stating this more carefully... The largest structure we have
synthesized in the laboratory at this point is a very primitive
cell-type wall built of lipids. No doubt, there are tens of millions
of atoms that go into these structures, but they are extremely simple
compared to a bacteria, and by no means do they approach reproducing
life forms. They don't even approximate useful cell walls, as there
are no holes... and even bacteria need to eat and poo.

We have no mechanism yet to describe the production of proteins
containing more than a paultry number of amino acids. Amino acids
don't spontaneously form polymers without a lot of tricky assistance.

I would be pretty darn impressed if we could show a plausible scenario
for the spontaneous emergence of just the citric acid cycle.

In conclusion, it is ridiculous to expect to observe abiogenesis
directly in the lab. It is many trillions of times more likely that a
chicken would spontaneously give birth to a dinosaur without
assistance from Jack Horner!

Nevertheless, there is enough of a lead to continue to investigate how
abiogenesis could have occurred terrestrially. Even if you buy into
panbiogenesis, life had to arise somewhere first, or "God Did It"(TM).

The most interesting concept I've run into during these studies is
emergence. Totally fascinating stuff that.

-Kelly

(*The molecular weight of E. coli lipid A is 1798.8, whereas that of
the previously proposed (33, 34) R. etli CE3 lipid ... is predicted to
be 2313.31)