Friday, February 22, 2008

Can Chemical Evolution Work?

In a previous blog, Why the Search for Extra-Terrestrial Intelligence (SETI)? , I discussed how the SETI project has been dramatically unsuccessful in finding signs of extraterrestrial intelligence, thus unsuccessful in finding evidence supporting the premise that life can arise spontaneously from non-life. I pointed out that there are other, more convincing, scientific avenues for examining this issue, and that such one avenue is biology, which I might discuss another time. This is that time.

Miller’s Experiment

In 1953, Stanley L. Miller, using the ideas and guidance of Harold C. Urey, applied an electric discharge (spark) to a mixture of ammonia, methane, hydrogen and water vapor for a week, obtaining a small amount of some amino acids. Since amino acids are the building-blocks of living things, the experiment made news as evidence for life arising spontaneously from non-living matter. Since then, many faults of the experiment were pointed out, so many other variations of the experiment were done to try to correct these faults and to get favorable results. These variations were generally either flawed as well, or unsuccessful. Lately, most evolutionists overlook the problem of getting primitive life from non-living matter, taking it for granted, and discuss evolution beginning from DNA or RNA. But if life cannot begin from purely natural processes, evolution has no foundation.

Miller’s experiment has been criticized as unrealistic, biased in favor of the desired outcome. Scientists now generally agree that earth’s early atmosphere was nothing like his ammonia-methane-hydrogen-water recipe. The oxygen in earth’s actual atmosphere would have destroyed the amino acids. His apparatus was something like a still, with an evaporator and condenser, but with a trap that isolated the amino acids as they were made, protecting them from the formic acid (as in bee venom) that was also made. The evaporator might be a model of the oceans and the condenser a model of the atmosphere, but what on earth does the trap represent?

But Miller’s experiment and its variations actually demonstrate the intrinsic difficulties of creating life from non-life. The biases actually help, because the experiments show that even with an artificial boost, life is nonetheless not produced. There are many principles of biology that are demonstrated by Miller’s experiment and its variations that explain why life cannot be produced from non-life by natural causes -- that all such attempts are intrinsically flawed.

Making Life

First, just making a few types of amino acids is not making life. Living things are made of enzymes and more complex organic molecules. To get life you need to at least connect a sequence of amino acids in a chain-type structure to get an enzyme -- and not just any sequence, but one that gives the enzyme a useful shape, because the shape is critically important to the function of the enzyme. An enzyme is an important, essential type of simple protein that is used as a tool to help construction and control of living things. Life uses more complex kinds of organic molecules, but to make life, you need to at least make enzymes.

Suppose someone told you that an earthquake or a tsunami could turn a forest into a pile of logs. You would probably find this plausible. But suppose he went on to say that this was proof that log cabins could be produced by natural causes. Surely you would object. How will the logs be cut to consistent lengths? How will they be notched to fit together? How will they be assembled into a useful shapes, with doors, windows, and roofs? Likewise, the amino acid building-blocks need to be assembled into enzymes with useful shapes.

Miller’s Experiment Examined

The following analysis of Miller’s experiment (and similar experiments) is based on a presentation by Timothy R. Stout of Creation Truth Outreach, Inc. and on other research that I did. I will use ‘plain English’ as much as possible, but will include the scientific terms in parentheses to make it easier for you to check my facts if you like.

Life is built from about 22 different kinds of amino acids -- 20 ‘standard’ kinds plus two variations used by a few unusual forms of life. Miller produced only four of these kinds in any significant quantity.

Miller’s experiment mostly produced tar (85%), a kind of chemical junk-yard of disorganized parts. He also produced formic acid (8%), which although an essential part of all amino acids, can be destructive, as mentioned earlier, and (about 3.5% of) other things. He also produced two of the simplest kinds of the amino acids (glycine and alanine, 2% each), which are water-repellent (hydrophobic). Two other, somewhat more complex amino acids (glutamic acid and aspartic acid, 0.02% each), which are water-attracting (hydrophilic), were produced. The other kinds of amino acids, which are mostly more complex in structure, were produced in only very tiny (trace) amounts, or not at all. There was no evidence that any of the amino acids had assembled into chains to form enzymes or any other sort of protein.

Problems, Problems, and More Problems

This was not a good mix for producing life. Enzymes need an amino acid sequence that generally alternates between the water-repellent and water-attracting types of amino acids. But because there was 100 times more of one kind than the other, half of the time when an amino acid needed to be added to a chain in progress (a polypeptide), there would be only a 1% chance of the correct kind. The simplest enzyme requires a chain of at least 57 amino acids, so the probability of successful assembly is 1% of 1% of 1% of 1% of 1% of 1% of 1% of 1% of ... 28 times, which basically translates to: impossible. Most simple proteins are chains of more than 100 amino acids.

With too many amino acids of the water-repellent kind, a forming chain of amino acids would be too ‘sticky’, causing tar to form instead of enzymes.

Another problem, of course, was that only four of the 20 'standard' kinds of amino acids were produced. This certainly eliminates many kinds of useful enzymes.

Another problem -- no ‘molecular chaperones’. Chemists know that most enzymes require ‘molecular chaperones’ for correct assembly, to prevent making a jumbled mess (aggregation) -- that is, making tar. Molecular chaperones are proteins that interact with unfolded or partially folded protein subunits, working to stabilize them, unfold them, and/ or to assist in their correct folding and assembly. In other words, you need life to build life. This is what happens when plants build themselves from dirt, and when animals build themselves from dead plants. But until you create life, you don’t have molecular chaperones to help you create life.

Another problem is that it takes more energy to join amino acids into chains than to break the chains apart. A basic principle of physics and biology is that a system, left alone, tends to go to its lowest-energy state (equilibrium), which for amino acids is broken chains. When life exists, there are mechanisms to protect the chains (proteins) from breaking; but before life is formed, there is no protection. Again, life needed to make life.

Another problem is that there was too much formic acid. A formic acid molecule can easily connect to the end of a chain of amino acids, stopping the chain from getting any longer. Since there were four times as many formic acid molecules as amino acid molecules, there was only a one-in-five chance for the chain to continue growing at each step. The probability of getting a chain of 100 amino acids at this rate is so tiny (1/5 to the 99th power) that even if there were as many amino acid molecules in the experiment as the number of atoms in the Milky Way galaxy, there would be little chance of getting even one chain this long!

Another problem is that molecules can also connect on the side of the amino acid molecules, forming ‘side chains’ inside of building the chain only in the correct direction. This problem gets rapidly worse if the chain gets longer, because there will be more and more locations where side-chains can grow. Mathematically, the probability of getting a chain of 100 amino acids for this reason alone is one chance in 2 x 3 x 4 x 5 ... x 98 x 99 (99! or 99 factorial). Now, all the atoms in the entire universe will not be enough to get one accidental protein 100 amino acids long!

Another problem is that the mix of amino acids that Miller produced in his experiment did not have the correct ratio of fundamental properties to make viable enzymes. Half of the amino acids should be ‘non-polar’ (the water-repelling kind), and the other half should be ‘polar’ (the water-attracting kind). Of the polar kind, half should be electrically charged, and the other half uncharged. Of the electrically charged kind, half should have a positive charge, and the other half negative. So the proportions should be:
  • 1/2 (50%) non-polar
  • 1/4 (25%) polar, uncharged
  • 1/8 (12.5%) polar, charged positive
  • 1/8 (12.5%) polar, charged negative
So what mix did Miller get? He got:
  • 99% non-polar
  • 0% polar, uncharged
  • 0% polar, charged positive
  • 1% polar, charged negative
Just another reason why the experiment failed.

Another problem involves the symmetry (‘chirality’) of the organic molecules. Amino acid molecules can have left-handed and right-handed shapes, just as shoes and gloves do. But in the construction of life, only left-handed amino acids are used, except glycine, which is symmetrical -- neither left-handed nor right-handed. And life only uses right-handed sugars. And for good reason, because if you were made of equal amounts of both chiralities of proteins, your body would not fit together correctly, and you would die. (Think of the problem of mixing left-handed and right-handed screws in a complex machine.) Now suppose there was one man made of organic molecules of chirality all opposite to the rest of life. (He would look ordinary unless you looked at him with a powerful microscope.) He would have trouble digesting his food, because it would have the wrong chirality (for him).

Now it happens that amino acids have ‘unstable chirality’ -- that is, a left-handed amino acid molecule will occasionally flip (racemize) into a right-handed shape. This happens slowly, taking about 10 to 100 years for most of the molecules to change chirality. Our bodies can correct for this slow degradation by replacing cells of our body, although in some tissues, like teeth, this can be tolerated. Forensic scientists actually use this phenomena to measure the age of teeth.

So the chirality problem is this: If chemical evolution works, it needs to develop a construction of proteins with sufficient complexity to survive and reproduce. Until that critical point, we don’t have life -- just life-in-the-making. But along the way, ‘chiral instability’ will destroy the partly-made life before it has a chance to develop mechanisms for self-repair. Chiral instability may take perhaps as much as 1000 years to destroy the progress of evolution, but even evolutionists don’t believe evolution works anywhere near that fast. Until a mechanism for reproduction is developed, there is no way for evolution to randomly ‘try’ methods for combating chiral instability until it ‘accidentally’ finds a working method. It has to get this (and the survival and reproduction methods) right the first time.


In other words, chemical evolution (if it works) needs to create potential life ‘designs’ over and over and over until one of them ‘works’ (actually lives and reproduces). But we have presented a long list of problems, each one of which prevents the production of even a small scrap of one enzyme, let alone a construction of various proteins with sufficient complexity to survive and reproduce. The problems presented don’t involve imagining what might have happened long ago. All of these problems (for getting chemical evolution to work) are based on facts and principles of organic chemistry that have been, and can be, demonstrated in a laboratory, coupled with mathematics and logic. Yet ALL of these problems would need to be overcome (contrary to the facts and principles of organic chemistry) to make chemical evolution work!

Those who patiently wait for SETI or experiments such as Miller’s to prove that life can arise spontaneously from non-life are ignoring logic and the facts of organic chemistry. Why are they such patient believers? I am convinced that they are biased by a fervent desire to deny a Creator, who they are afraid might require something of them.

P.S. If you would like to learn more about these and similar reasons why known physical principles prevent life from arising by natural causes, read Timothy R. Stout's pamphlet online.

P.P.S. I neglected to explain that when left- and right-handed versions of an organic molecule are possible, chemistry unguided by information (generally in the form of the design of other organic molecules), that is, when the chemical components are simply jostled by random motions, you will get equal numbers of the left- and right-handed versions, because the laws of physics alone show no preference for one over the other. It takes actual information to make a choice for the kind needed for the over-all design.

I also neglected to point out that for energy-efficient construction and functioning of life's various organic molecules, information in the form of specialized tools are needed. For example, tools called enzymes are designed to fit certain kinds of organic molecules. efficiently accessing the energy in them. For example, the enzyme lactase operates on lactose, pectase on pectin, lipase on glyceride, etc. The DNA information creates these tools to operate the machinery of life.

1 comment:

JC said...

from the journal "Scientific American":
"Even the simpler molecules are produced only in small amounts in realistic experiments simulating possible primitive earth conditions. What is worse, these molecules are generally minor constituents of tars: It remains problematical how they could have been separated and purified through geochemical processes whose normal effects are to make organic mixtures more and more of a jumble. With somewhat more complex molecules these difficulties rapidly increase. In particular a purely geochemical origin of nucleotides (the subunits of DNA and RNA) presents great difficulties."
Cairns-Smith, Alexander G.,
"The First Organisms,"
Scientific American,
252: 90, June 1985.