A couple of months ago I quoted from Lesli Orgel’s 1973 book on the origins of life. L. E. Orgel, The Origins of Life: Molecules and Natural Selection (John Wiley & Sons, Inc.; New York, 1973). I argued that on page 189 of that book Orgel used the term “specified complexity” in a way almost indistinguishable from the way Bill Dembski has used the term in his work. Many of my Darwinian interlocutors demurred. They argued the quotation was taken out of context and that Orgel meant something completely different from Dembski. I decided to order the book and find out who was right. Below, I have reproduced the entire section in which the original quotation appeared. I will let readers decide whether I was right. (Hint: I was).
All that follows is a word-for-word reproduction of the relevant section from Orgel’s book:
Most elementary introductions to biology contain a section on the nature of life. It is usual in such discussions to list a number of properties that distinguish living from nonliving things. Reproduction and metabolism, for example, appear in all of the lists; the ability to respond to the environment is another old favorite. This approach extends somewhat the chef’s definition “If it quivers, it’s alive.” Of course, there are also many characteristics that are restricted to the living world but are not common to all forms of life. Plants cannot pursue their food; animals do not carry out photosynthesis; lowly organisms do not behave intelligently.
It is possible to make a more fundamental distinction between living and nonliving things by examining their molecular structure and molecular behavior. In brief, living organisms are distinguished by their specified complexity.*· Crystals are usually taken as the prototypes of simple, well-specified structures, because they consist of a very large number of identical molecules packed together in a uniform way. Lumps of granite or random mixtures of polymers are examples of structures which are complex but not specified. The crystals fail to qualify as living because they lack complexity, the mixtures of polymers fail to qualify because they lack specificity.
* It is impossible to find a simple catch phrase to capture this complex idea. “Specified and. therefore repetitive complexity” gets a little closer (see later).
These vague ideas can be made more precise by introducing the idea of information. Roughly speaking, the information content of a structure is the minimum number of instructions needed to specify the structure. One can see intuitively that many instructions are needed to specify a complex structure. On the other hand, a simple repeating structure can be specified in rather few instructions. Complex but random structures, by definition, need hardly be specified at all.
These differences are made clear by the following example. Suppose a chemist agreed to synthesize anything that could describe [sic] accurately to him. How many instructions would he need to make a crystal, a mixture of random DNA-like polymers or the DNA of the bacterium E. coli?
To describe the crystal we had in mind, we would need to specify which substance we wanted and the way in which the molecules were to be packed together in the crystal. The first requirement could be conveyed in a short sentence. The second would be almost as brief, because we could describe how we wanted the first few molecules packed together, and then say “and keep on doing the same.” Structural information has to be given only once because the crystal is regular.
It would be almost as easy to tell the chemist how to make a mixture of random DNA-like polymers. We would first specify the proportion of each of the four nucleotides in the mixture. Then, we would say, “Mix the nucleotides in the required proportions, choose nucleotide molecules at random from the mixture, and join them together in the order you find them.” In this way the chemist would be sure to make polymers with the specified composition, but the sequences would be random.
It is quite impossible to produce a corresponding simple set of instructions that would enable the chemist to synthesize the DNA of E. coli. In this case, the sequence matters; only by specifying the sequence letter-by-letter (about 4,000,000 instructions) could we tell the chemist what we wanted him to make. The synthetic chemist would need a book of instructions rather than a few short sentences.
It is important to notice that each polymer molecule in a random mixture has a sequence just as definite as that of E.
coli DNA. However, in a random mixture the sequences are not specified, whereas in E. coli, the DNA sequence is crucial. Two random mixtures contain quite different polymer sequences, but the DNA sequences in two E. coli cells are identical because they are specified. The polymer sequences are complex but random; although E. coli DNA is also complex, it is specified in a unique way.
The structure of DNA has been emphasized here, but similar arguments would apply to other polymeric materials. The protein molecules in a cell are not a random mixture of polypeptides; all of the many hemoglobin molecules in the oxygen-carrying blood cells, for example, have the same sequence. By contrast, the chance of getting even two identical sequences 100 amino acids long in a sample of random polypeptides is negligible. Again, sequence information can serve to distinguish the contents of living cells from random mixtures of organic polymers.
When we come to consider the most important functions of living matter, we again find that they are most easily differentiated from inorganic processes at the molecular level. Cell division, as seen under the microscope, does not appear very different from a number of processes that are known to occur in colloidal solutions. However, at the molecular level the differences are unmistakable: cell division is preceded by the replication of the cellular DNA. It is this genetic copying process that distinguishes most clearly between the molecular behavior of living organisms and that of nonliving systems. In biological processes the number of information-rich polymers is increased during growth; when colloidal droplets “divide” they just break up into smaller droplets.