Abiogenesis A brief history
Even though Darwin himself focused on the origin of species, some scientists have tried to apply the concept of evolution to the first life to form the concept of abiogenesis. In 1924, Russian biochemist Alexander Oparin proposed that living cells arose gradually from nonliving matter through a sequence of chemical reactions. According to Oparin, gases present in the atmosphere of primitive earth, when induced by lightening or other sources of energy, would react to form simple organic compounds. These compounds would subsequently self-assemble into increasingly complex molecules such as proteins. These, in turn, would organize themselves into living cells.
In 1953, Stanley Miller and Harold Urey tested Oparins hypothesis by conducting an experiment that attempted to simulate the atmospheric conditions of primitive earth. In their experiment, water boiled into vapor at the bottom of a flask and then passed through an apparatus, combining with ammonia, methane, and hydrogen. They then subjected the resulting mixture to a 50,000-volt-spark before cooling and collecting it in a trap at the bottom of the apparatus. When Miller and Urey examined the resulting tar-like substance, they found a collection of amino acids, the building blocks of life.
Abiogenesis The problems
Unfortunately Millers attempt to demonstrate the possibility of abiogenesis (that life can come from non-life) did not honestly simulate conditions on the primordial earth. For example, oxygen was evidently present on the early earth -- but the presence of oxygen prohibits the development of organic compounds. Even though we require an abundance of oxygen to survive, our bodies also need many special adaptations in order to manage it safely. In the 1950s, origin-of-life researchers assumed that the early earth had very little oxygen. Geological evidence now suggests, however, that substantial quantities of oxygen were present in the earths earliest atmosphere. If the gases that scientists now believe were present on the early earth were to be used in the correct proportion, no such amino acids are produced.
But let us suppose that Millers experiment faithfully recreated conditions on the early earth, would the experiment be validated? A further major difficulty is that such experiments cannot produce the right kinds of amino acids. Amino acid conformations exist as mirror-isomers. In other words, there are left-handed (L-form) amino acids, as well as right-handed (D-form) amino acids. The amino acids that comprise living proteins are of the left-handed form, yet in simulations such as Millers, an equal mixture of left-handed and right-handed amino acids are produced. All known natural mechanisms by which amino acids are produced, produce amino acids in roughly the same proportion of right- and left-handed forms. But let us suppose that some naturalistic mechanism were discovered which could indeed segregate the left-handed forms needed for life. It would still remain inexplicable how the L-form amino acids became correctly ordered with the proper links (peptide bonds) to form proteins. The odds would still be stacked highly against obtaining even a single protein from a primordial soup made up of exclusively L-form amino acids.
But let us suppose that not only was a naturalistic mechanism discovered which could segregate the left-handed forms needed for life, but also a soup was discovered which possessed a mystical capacity to form proteins. To form a living cell requires hundreds of specialized proteins that need to be precisely coordinated. We would also need to produce DNA, RNA, a cell membrane, and a host of other chemical compounds -- not to mention arranging them into their correct locations to perform their respective functions.
Clearly to get from the Miller-Urey experiment to a living cell by unguided materialistic processes requires that improbabilities be stacked upon improbabilities. For this reason, Dean Kenyon rightly concludes: It is an enormous problem, how you could get together in one tiny, sub-microscopic volume of the primitive ocean all of the hundreds of different molecular components you would need in order for a self-replicating cycle to be established.