Mystery Of The Origin of Life



Abiogenesis, as distinct from evolution, is the study of how the first simple living things were assembled from simpler prebiotic molecules. Evolution comes after abiogenesis because you have to have something living in order for it to evolve. Evolution could be said to explain the survival of the fittest but not the arrival of the fittest.

Initially it was assumed that life arose on earth through natural means. It was thought that some kind of primordial “soup” combined with UV rays, lightning, heat etc could explain how basic molecules assmembled into complex cells which at the molecular level are actually incredibly complex “factories”. When Charles Darwin formulated his famous theory of evolution, it was thought that cells were merely “blobs” of organic matter, not the complex structures we know them to be since the invention of powerful microscopes.

Following on from the discovery of the structure of DNA by Crick and Watson, scientists discovered that the molecules that form the “ladder” between the double helices, form apparently random patterns. The molecules involved are adenine, cytosine, thymine, and guanine, (abbreviated as A,C,T,G). It was later disovered that the order of these molecules isn’t random at all but in fact is a code or “blueprint” for building proteins in a cellular factory.

Where the abiogenesis theory runs into difficulty is in the high specificity of the proteins i.e. their structure is highly unlikely to occur randomly. These proteins are very specific in the sense that if they don’t have a precise specified molecular ordering and three-dimensional structure, then the structure can perform no useful function. Let’s take as an example a short protein (150 molecules) and keep in mind that hundreds of different protein types are required to make a functional cell. The factors involved in the specificity could be summarized as follows:

  1. The molecular chain is composed of amino acids and there are two chains, one on each side of the helical ladder.
  2. The bonds between neighbouring molecules must be a peptide bond. Peptide and non-peptide bonds are equally likely so the probability is 0.5 for each bond. When you multiply 0.5 by itself 150 times, the probability becomes extremely small (7 x 10^-46)
  3. In addition to having peptide-only bonds, amnio acids are left-handed and right-handed. In the double helix, one side of the ladder must contain all left-handed acids and the other, all right-handed acids. Again the probability is 0.5 for each bond and the overall probablity is 7 * 10^-46.
  4. The next level of specificity is the sequence of A,C,T,G. If these don’t occur in exactly the right sequence, you end up with a protein that does nothing, it has no function. The probability of the amino acids bonding in the correct sequence is 0.25^150 = 4 * 10^-91
  5. The above specific conditions must occur on both sides of the double helix.
  6. Approximately 200 specific proteins types are required to build a functioning cell.

In addition to the above problems, it’s worth noting that proteins are required to build DNA and DNA is required to build proteins so we have a chicken and egg situation. Also, the cell is the minimum viable living organism e.g the single-cell amoeba. All the parts of the cell need to be in place or the cell cannot survive. It’s a bit like a car engine that must have all the parts in place. You break one part and the whole thing fails to operate.

For anyone who is familiar with the CAD/CAM process used in manufacturing, the design is done on a computer and the instructions are sent to a CNC machine to which creates the component. The way DNA is used to build new proteins is a very similar process. The sequence of A,C,T,G pieces is exactly like a computer program i.e. a set of instructions used to carry out the task of building new proteins. The important point here is that DNA contains “information” and information only comes from an intelligent agent, e.g. a human mind. The purpose of DNA is to carry information, it does not provide a mechanical function. However it is used to build functional mechanisms.

The big question then for science is where does this information come from? Information cannot come from a random source. In fact random processes can only destroy information. Since science operates on naturalistic basis, it is assumed that abiogenesis is a random, unguided process with no end-goal. Since DNA contains information, a random, unguided process cannot be responsible for the production of DNA and hence life itself.

To imagine that there is a natural explantion for the origins of life is like thinking it’s possible to repeatedly dump a box of scrabble letters on a table and have them “randomly” arrange themselves into a Shakespearean play! Even if the same thing was repeated for billions of years, there wouldn’t be enough time because of the absolutely tiny probabilities involved.