The origin of the first cell is a major challenge for evolutionist.
The origin of the first biological cell from nonliving chemicals is the most important problem challenging the worldview of those who think life arose entirely by natural, random, and purposeless processes. That is because a living and reproducing cell is required before any sort of naturalistic evolution can get started. This origin of the first cell is often referred to as abiogenesis.
Abiogenesis is a very challenging problem that has been awaiting a solution for decades. Most textbooks pass lightly over the problem and simply leave the students ignorant of why the problem exists. Over time a few solution attempts have been advanced and one or another of these is often found in textbooks. But it is universally recognized that these attempts are woefully inadequate. For example New Scientist magazine quotes the famed professor Paul Davies saying, “Nobody knows how a mixture of lifeless chemicals spontaneously organized themselves into the first living cell.”(1) All students should be given a basic understanding of why this is and an acquaintance with the most important issues that must be dealt with by a proposed hypothesis explaining the origin of the first cells from naturally occurring nonliving chemicals.
The first cell requires a complex system of coordinated molecules that work together like the parts of a machine to metabolize the surrounding sources of energy and to regularly reproduce the system before any form of evolution can start taking place. In all known life forms the complex of machines are largely composed of proteins with a control system that enables orderly operation of the machines and the system’s self-replication. The control system is embodied in the cell’s DNA along with the specifications for the proteins. A few of the more important and essential elements of this abiogenesis problem are discussed briefly below.
Origin of proteins and systems:
Before the first cells could arise from nonliving chemicals a system of proteins must be brought together to form the components of a machine. These proteins cannot be some randomly occurring set; rather, they must be highly specific in order to work together like the parts of a complex machine to perform many necessary functions. Each of these proteins is made up of a long chain of amino acids ordered in a very specific sequence. A typical chain length is 400 specific amino acids. To have a specific sequence of amino acids occur by random processes is difficult to justify so let’s first consider a very favorable idealized case. Assume we have a beaker or vat filled with nothing but the 20 amino acid molecules needed for these proteins. If only random events are at work there will be one chance in 20400, or about 10520, of obtaining the specific protein sequence needed. This number is so large it is very difficult to comprehend. For comparison one might note that astronomers estimate that there are about 1080atoms in the observable universe. But even that is an extremely tiny number compared to 10520 ! So by random unguided processes there is no useful chance of obtaining any one specific protein. What is worse is that conservative estimates of the number of coordinated proteins needed to form the system of molecular machines in the simplest cell are at least several hundred. A 2006 estimate by Hamilton Smith at the J. Craig Venter Institute came up with a minimum size of 387 proteins.(2) At present there is no reasonable way known to overcome the immense improbability of a random unguided process producing a protein system like this even under ideal conditions.
Folding and Chirality:
The problem is actually much larger than just obtaining the necessary sequence of amino acids found in the protein chains because these chains must be folded into the correct three dimensional shape in order to function as parts of molecular machines. The necessary shape for functionality, once we have the required sequence, is most often not one of the naturally occurring shapes. In living cells there are molecular machines called chaperones that enable this folding in the correct manner and still other machines conduct the new protein to the place where it is needed. But how is this done before the first cell was complete? Further, each of the 20 amino acids naturally occurs in two different three dimensional forms or stereoisomers with a symmetry like our left and right hand. This left and right handed symmetry is referred to as chirality. However, the proteins in living systems are made exclusively of left handed amino acids! If a right handed amino acid gets into the protein chain it usually cannot fold into the correct functional shape. So this folding and stereoisomers add two additional dimensions of complexity to obtaining a system of proteins. But here is another problem: all naturally occurring chemical processes produce a fifty-fifty mixture of the two stereoisomers of each amino acid. So how did the first cells exclude the right handed amino acids molecules – fully one-half of the naturally occurring molecules?
Destructive chemical processes:
Any naturally occurring environment will be far from ideal and there will be a number of processes working against the assembly of a system of proteins with the correct sequences of amino acids of exclusively left-handed chirality all folded in the three dimensional shape that will make them functional parts of a machine. Let’s briefly consider four of the most basic natural chemical processes that are working to take protein chains apart. First if there is a large proportion of water present, like a pond, lake or ocean, then the water itself will react with the amino acid chains and break the bonds by a process called hydrolysis. Living cells have elaborate mechanisms to protect their proteins from hydrolysis but how would this work before the first complete cell? Second, if there is sunlight or lightning present then there will be substantial amounts of ultraviolet light present. The photons of UV light have enough energy that they will break down the amino acid bonds. Third, if there is any free oxygen present then the oxygen will vigorously react with the protein chains destroying them. The process of photo-dissociation due to UV light from the sun hitting water vapor molecules in the atmosphere ensures that there has always been some free oxygen present in the atmosphere. 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 geologists conclude that there has always been some significant amount of oxygen in the Earth’s atmosphere. Fourth, in any natural environment there will be a great variety of chemicals contaminates present that will react with the amino acids as the proteins form and that will destroy the needed sequence and three dimensional shapes and eliminate any functionality.
DNA and information:
Of course all living cells have the information necessary for assembling proteins and a control system that regulates the operation of the cell’s molecular machines stored in DNA. So some biologists have conjectured that DNA and RNA came first before the cell. But that would entail all of the same kinds of problems with their assembly by natural processes as with proteins. In any case a living cell would require a complete system of information and a control system right from the start! This obviously raises the question, where did the information come from? Systems of information are never observed to arise from random processes. Some biologists insist that it must happen because, “here we are!” But they can offer no physical cause and effect hypothesis that is testable. On top of that, all of the same general kinds of destructive processes discussed above also operate to destroy DNA and RNA as well as proteins. The bottom line is that DNA requires the protection and operating machinery of a cell before it can do anything or even survive. The information content of the first cell must be accounted for in a rigorous and rational way.
These are some of the basic problems that must be simultaneously overcome to develop a potentially successful hypothesis explaining the origin of the first cells from nonliving chemical in a natural environment. No hypothesis has yet come anywhere close to overcoming these problems. Some have tried to avoid UV light and free oxygen by supposing the first cells developed deep in the oceans; but even so all the rest of the problems above still comprise an insurmountable obstacle. The bottom line is that given all the time, energy, and material in any presumed history of the universe there is no conceivable way for the origin of the first cell to occur by random unguided processes.
It is common to hear assertions that solution of the abiogenesis problem is just a matter of time, but with so many intractable problems involved it is clear that such an assertion is merely a bluff. Without a doubt anyone who makes any substantial step forward on the abiogenesis problem will win a Nobel Prize. Clearly, it will require many major steps forward to even bring a solution within sight. In the meantime everyone interested in origins or biology needs to have a clear basic knowledge of the basic difficulties involved in the abiogenesis problem in order to be considered reasonably well educated.
In contrast to the naturalist who claims that only random and purposeless processes exist, as soon as we consider the possibility that intelligence and purposeful design are involved as well as random processes, then the abiogenesis problem takes on a distinctly different light. With purposeful intelligent design involved, the high level of systematic organization and design just reflect on the high level of the intelligence and design capability of the designer involved. Likewise the above mentioned need for a source of information is solved by the involvement of intelligence in the origin of life because intelligence is the only source of information that is observed by science. Thus the science of abiogenesis clearly demands that all interested in scientific truth will give careful open minded consideration to the involvement of an intelligent and purposeful designer.
(1) Davies, P., Australian Centre for Astrobiology, Macquarie University, Sydney, New Scientist 179:32, 12 July, 2003.
(2) Smith, H. O. Essential genes of a minimal bacterium, Proc. Natl. Acad. Sci. 103:425–430, 2006