One of the explanations put forward to explain the origin of life is the Chemical Evolution theory. In essence, it suggests that basic chemicals underwent a transition to form living cells. In order to understand that the steps proposed for chemical evolution make a very unlikely story, consider the following analogy. This explanation is of something much more mundane than life. It is the story of the origin of a child’s yellow bouncing ball. The story is adapted from the writings of Professor E.H. Andrews of the University of London, England, in his book From Nothing to Nature.
"One day I was walking along the beach when I saw something yellow in the sand. It was one of those small, solid rubber balls that bounce so well. How did it get there? You may think that a child, playing on the beach, had lost it, but I am going to give you a different explanation. Hundreds of years ago on a tropical island, there grew, side by side, a coconut palm tree and a rubber tree. One day a coconut fell from the palm striking a stone, which chipped off a piece of the shell, It was not long before the insects found the hole in the coconut and began to nibble away until eventually the shell was hollow. It so happened, about that time, that a second nut fell from the palm tree. In falling it struck one of the branches of the rubber tree, breaking off a piece of bark. Milky rubber latex began to flow from the damaged branch and drip to the ground. It so happened (again!) that the empty coconut shell lay directly below the damaged limb, with the small hole in its shell facing upwards. By a wonderful coincidence the rubber latex began to drip into the hole until a pool of latex collected in the coconut shell. Then a wind sprang up, carrying dust across the island, and some of the dust contained natural sulphur, which fell into the hole and settled on the latex. Finally, the wind blew a leaf over the hole, and latex drips sealed it. The sea eventually swept the coconut shell away. As the shell bobbed on the waves, the rubber latex mixed with the sulphur and sand and rolled itself into a ball. Now when sulphur was heated with rubber by the hot sun, it vulcanized the rubber into a solid, elastic lump. The latex rolled around inside the coconut shell while it was being vulcanized, and so took on a round shape. Eventually, the coconut was dashed against some rocks and broke, releasing the ball, which floated, and was finally thrown up on a beach where I found it!"
The story took a series of coincidences, each of which is possible but unlikely, and joined them together to explain how the ball came to be on the beach. Similarly with chemical evolution, there are about a dozen steps which have to be just right. Although we can imagine that any one of them might have occurred, strung together they make an unlikely story indeed. While it sounds like fantasy, at the same time you cannot say that it is wholly impossible.
Like the story of the origin of the yellow ball, the theory of chemical evolution puts together a series of unlikely events. All of these had to happen in sequence in order for the first living cells to exist. The events postulated include:
- The Earth’s early atmosphere had to contain a particular group of small molecules.
- There had to be just the right energy source to cause them to join together, but not break down again.
- The larger molecules which formed had to be washed down by the rain, and therefore be somewhat soluble in water. However, the very soluble ammonia molecules had to remain in the atmosphere.
- The sparingly soluble large molecules had to remain in the water as it ran over the rocks in order to protect them from decomposition by ultraviolet light.
- The molecules had to remain stable while they became concentrated enough to link together to form chains.
- An appropriate catalyst was needed to link the organic molecules so they could form larger molecules in the water.
- These newly-formed larger molecules had to be just the right molecules, present in the right concentration, to allow them to link together to form the special coded order required in proteins and DNA.
- These first half-living molecules needed to have the same left handed twist, since all of life’s proteins are made from only left handed amino acids.
- Organic droplets had to form and remain stable long enough for some internal process to turn them into cells.
- A membrane had to form, that would protect the contents of the new cell, and yet allow nutrients and waste to pass through.
- The first living cells had to live long enough, in rather unfavourable conditions, to develop proteins with enzymatic activity and mechanisms for cell division.
Any one of these steps might conceivably have occurred, but when put together in sequence they present a rather unconvincing speculative account of the origin of life. The theory of chemical evolution involves a list of unlikely conditions, including that somehow the special coded order in DNA had to happen. Ultimately the right organic molecules had to be present in the right amounts to link up into proteins and DNA.
Furthermore, this theory depends on the hypothesized existence of ‘protocells’ – small enclosures containing components from which living cells might have developed. By definition, living cells are the smallest entity in which all the activities characteristic of life are carried out. How these hypothetical ‘protocells’ could change into true cells remains unknown.
As well, it seems that an undirected flow of energy through a primordial atmosphere and ocean is, at present, an inadequate explanation for the complexity associated with even simple living things. Scientific data just does not support the thesis that life arose by chance.
Our understanding of the self organization of matter is still in its infancy. There may be some surprises round the corner, but at present chemical evolution can only be defended as a philosophical viewpoint, and not a conclusion of science. The facts currently available do not seem to provide a basis for postulating “the basic chemicals to cell transition” proposed by the origin of life theories. Yet many scientists accept chemical evolution. It is not on account of definitive experiments, but rather on the basis of their presupposition that a Creator doesn’t exist.
Currently there are frequent reports of interesting findings relevant to this area. Yet, we still have a long way to go in the quality of our cross examination if we are to get a better understanding of the mystery of life’s origin.