Abiogenesis: The Skeptic’s View

The enormity of the abiogenesis problem can be seen even if one starts from a very favorable initial condition. With the hope of assembling a functional system of proteins needed for life, suppose that we have all of the 20 amino acids of life available with an equal probability of adding each to a growing chain of amino acids. Then there is a 1 in 20 chance of getting the right amino acid with any addition to the chain. The proteins of life system contain a specific chain of several hundred amino acids.  Consider a specific chain of 400 amino acids. The probability of getting this specific sequence is 1 in 20400 or about 10520. One would have to randomly make 10520 chains, each 400 amino acids long, to get a single even chance of getting the needed sequence. This is a number so large that it is very difficult to comprehend. It is much larger than anything ‘astronomical’. In fact an estimate of the total number of atoms in the observable universe, including all of the atoms in all of the stars in all of the billions of galaxies that can be seen by all of the telescopes, is ‘only’ about 1080. This is a very small number compared to 10520. In fact 10520 is larger than 1080 x 1080 x 1080 x 1080 x 1080 x 1080 which equals ‘only’ 10480.

In an effort to be wildly optimistic, suppose that all of the atoms, 1080, in the observable universe interacted with all the other atoms, 1080, in the observable universe a million, 106, time a second for the last ten billion, 1010, years! Sense there are about 3x107 seconds in a year, this would give 1080x1080x106x1010x3x107=3x10183. This is still miniscule compared to the number of random events, 10520, needed before we can expect to obtain our medium size protein molecule. In fact there seems to be no way of being sufficiently optimistic, even with all of the time and material in the universe, to reasonably expect one specifically needed amino acid sequence to actually occur. Even if by some great fortune the right sequence did occur, one would still have only one molecule, which by itself can accomplish nothing.

While we are waiting for these amino acid chains to build up there are several processes trying to tear them down. In a body of water, the water itself will reacts with the chains and break the bonds by a process called hydrolysis. Ultraviolet light hitting the amino acid chains will break them up. Any oxygen present will react very vigorously and destroy the amino acid chains. The process of photo-dissociation of water vapor has been a source of oxygen in the atmosphere since the Earth formed. No solid consensus has been reached on the amount of oxygen present in the early atmosphere but there is sufficient evidence in the geologic record to make some geologist conclude that there has always been some oxygen in the Earth’s atmosphere.

Another problem is that these organic molecules have both a left and right-handed forms, which are mirror images of one another in three-dimensional space. So far all natural abiotic sources of amino acids produce an equal mixture of handedness in these molecules. But amazingly all of the amino acids in the proteins of life systems are exclusively left-handed so the chain building must exclude all of the right-handed amino acids somehow. Even if a source of left-handed molecules is found the chain building process must exclude the right-handed forms coming from the presently known chemical processes. Some hopeful methods of doing this have been proposed and published but none have been experimentally verified yet.

Even after all of the above is accomplished the amino acid chain must be properly folded in to the right three-dimensional shape to form a functional protein molecule. These proteins cannot be any randomly occurring protein because they must fit together as the parts of a very complex biochemical system or machine. This machine must protect its parts from the environment while it extracts energy and materials from the environment to grow and reproduce. It has been estimated that even the simplest conceivable life system would require at least two thousand different proteins that fit together as the parts of a machine. By contrast the life system of humans is thought to employ over 100,000 different proteins.

Thus the abiogenesis problem is so enormous that it is understandable that origins of life researchers are excited at every possibility of a step forward. It is also understandable that the skeptics remain exceedingly skeptical. Little seems likely to change in this standoff unless some radically new principles are recognized and brought into play.

Note:

Every student should have an understanding of these facts. But, as weaknesses of the current abiogenesis theories, these facts are routinely censored out of all current and proposed textbooks. This situation is contrary to Texas law and must not be continued. To continues this situation constitutes willful deceit.