"Signature in the Cell"
by Stephen Meyer

Another "long argument"

In Signature in the Cell leading ID theorist Stephen Meyer argues that the complex, specified information in DNA could not have arisen solely through the action of undirected natural processes. The information content must have arisen from a mind – an intelligent designer. In fact, this is the only realistic scientific explanation. David Swift reviews Meyer’s landmark book.


‘One long argument’ – that’s how Darwin described his On the Origin of Species in which he drew together evidence from a range of disciplines to support his theory of evolution through the action of natural selection. In his Signature in the Cell Stephen Meyer adopts a similar approach to show that the information encoded in DNA clearly points to a designer. And in doing so he recounts his own journey of discovery: from being a geophysicist, he went to Cambridge to study the philosophy of science, and then to do his Ph.D. on the origin of life. So he is well qualified to write on the subject: not only the science, but also to set it in its wider context. And he explains how his investigations progressively led to his conclusions about the necessity of intelligent input in the origin of life.

He starts with a very helpful Prologue in which he reviews how Intelligent Design (ID) thinking emerged as we elucidated the structure and workings of the cell, especially the genetic machinery used in the replication and expression of DNA. He emphasises that, despite caricatures to the contrary, ID is not based on religious or biblical dogma, but on recent scientific discoveries that require satisfactory explanations.

The challenge of information in biology

From the scientific revolution onwards – right into the 21st century – continuing scientific discoveries have led to an increasingly materialistic view of the universe. This has included biology, where elucidating the components and mechanisms of molecular biology have banished vitalism, as we have realised that biology works through natural processes, albeit involving very complex and specific biological macromolecules. However, as Meyer points out, the specified complexity of biology at the molecular level presents a new and formidable explanatory challenge: how did such complex systems arise?

A particular enigma of course for an evolutionary origin of life is the interdependence of proteins and DNA: replication of DNA requires proteins, and the synthesis of proteins requires various RNAs to implement the genetic code, as well as the crucial role of DNA to specify their amino acid sequences.

To try to get out of this chicken-and-egg situation, and because some RNA can have a catalytic as well as information-mediating role, it has been proposed that the earliest replicating systems may have been based on RNA, from which the current system of interdependent proteins and nucleic acids evolved. Meyer has a very useful chapter explaining the many pitfalls of the RNA World. Of particular note, as well as mentioning the chemical problems with RNA, he emphasises that even ribozymes (RNAs with enzymatic activity) need to have a suitable sequence that will enable them to fold and have active sites – i.e. exactly the same sort of problem that besets trying to find a functional protein.

Ultimately, he argues, the problem is one of information. This is because at the heart of biology are a large number of macromolecules – notably proteins whose functions are determined by, and completely dependent on, their sequence of amino acids (as encoded in DNA). And, although some variation is permissible in their sequences, functional proteins are still exceedingly rare within the set of possible amino acid sequences of a suitable length. Hence, in effect, their amino acid sequences are dependent on information – information as to which sequences will fold into a specific three-dimensional structure and have appropriate amino acids in the right places to form, for example, the active sites of enzymes.

So the question becomes – how did that information arise?

Intelligent Design is the only realistic explanation

Meyer then takes a few chapters to discuss the possible options, especially those considered by mainstream scientists. They can be summed up, in the words of Jacques Monod, as by chance or necessity:

Either the sequences that work could have been hit upon by chance; but, as he says, those scientists who have actually looked at this (rather than merely accepted the popular view) have concluded that this is not a realistic explanation. The number of possible sequences vastly exceeds the temporal and spatial resources of the universe. As Cairns-Smith has said, “very soon indeed long waiting periods and massive material resources become irrelevant”.

Alternatively, it is suggested that chemical properties, such as natural affinities between the nucleotides, might have led to useful sequences. But these sorts of properties in principle cannot explain the specified sequence of nucleotides in DNA which in order to convey information “must be as physically indeterminate as the sequence of words on a printed page”, quoting Michael Polanyi.

He concludes, therefore, that the specific useful sequences in DNA could not have arisen solely through the action of undirected natural processes: their information content must have arisen from a mind – an intelligent designer. It is the only realistic explanation.

This conclusion is of course a ‘red rag to a bull’ so far as the mainstream scientific community is concerned, with most objecting vehemently that any explanation such as this just isn’t science. Meyer addresses various aspects of this objection, stressing that ID is based on scientific evidence, and he appeals to the historical scientific approach of trying to identify the most reasonable explanation to account for past events. I think one of his most helpful comments is this, in answer to those who would a priori reject ID because, so far as they are concerned, it isn’t scientific:

The argument shifts the focus from an interesting question of truth to a trivial question of definition. ... to say that a claim about reality “is not science” according to some definition says nothing about whether the claim is true – unless it can be assumed that only scientific theories are true. A definition of science does not, by itself, tell us anything about the truth of competing statements, but only how to classify them.

So I think one of the strengths of Meyer’s book is how he argues that we should not be blinkered in the sorts of explanations we are prepared to consider. We cannot validly exclude the possibility of the action of a mind as a source of information in the natural world – indeed the evidence indicates it is a necessary factor in the origin of life – even if it begs the question of how that action was effected.

Overall I think Signature in the Cell is not only an excellent introduction to Intelligent Design but it also includes in-depth discussion of some of the key scientific and philosophical issues. My one criticism is that I think it is over-long: not that the author tries to cover too much ground, but that quite often he takes longer than necessary to explain his points, making what is otherwise a very informative book less readable than it might have been.

David Swift, B.A.(cantab), M.Sc., author of Evolution Under the Microscope (Leighton Academic Press, 2002)
March 2010