Signature in the Cell continues to stir up debate and attract attention as Thomas Nagel’s selection of SITC as one of the Books of the Year brought on an interesting series of letters, where Nagel was attacked (he responded, and he was attacked again) by a Darwinist who told people forgo reading SITC and instead just read Wikipedia.
This week, author Stephen Meyer himself responds in a letter, with a shortened version published yesterday. (Nagel himself responded with a letter that is published on the same page by TLS.) Below is Meyer’s letter in its entirety:
To the Editor
The Times Literary Supplement
Natural Selection and the Origin of Biological Information
I’ve been honored by the recent attention my book Signature in the Cell has received in your letters section following Thomas Nagel’s selection of it as one of your books of the year for 2009.
Unfortunately, the letters from Stephen Fletcher criticizing Professor Nagel for his choice give no evidence of Dr. Fletcher having read the book or any evidence of his comprehending the severity of the central problem facing chemical evolutionary theories of life’s origin.
In Signature in the Cell, I show that, in the era of modern molecular genetics, explaining the origin of the first life requires—first and foremost—explaining the origin of the information or digital code present in DNA and RNA. I also show that various theories of undirected chemical evolution—including theories of pre-biological natural selection—fail to explain the origin of the information necessary to produce the first self-replicating organism.
Yet, in his letters to the TLS (2 and 16 December), Stephen Fletcher rebukes Nagel (and by implication my book) for failing to acknowledge that “natural selection is a chemical as well as a biological process.” Fletcher further asserts that this process accounts for the origin of DNA and (presumably) the genetic information it contains.
Not only does my book address this very proposal at length, but it also demonstrates why theories of pre-biotic natural selection involving self-replicating RNA catalysts—the version of the idea that Fletcher affirms—fail to account for the origin of genetic information.
Indeed, either Dr. Fletcher is bluffing or he is himself ignorant of the many problems that this proposal faces.
First, “ribozyme engineering” experiments have failed to produce RNA replicators capable of copying more than about 10% of their nucleotide base sequences. (Wendy K. Johnston, et. al, “RNA-Catalyzed RNA Polymerization,” Science 292 (2001): 1319-25.) Yet, for natural selection to operate in an RNA World (in the strictly chemical rather than biological environment that Fletcher envisions) RNA molecules capable of fully replicating themselves must exist.
Second, everything we know about RNA catalysts, including those with partial self-copying capacity, shows that the function of these molecules depends upon the precise arrangement of their information-carrying constituents (i.e., their nucleotide bases). Functional RNA catalysts arise only once RNA bases are specifically-arranged into information-rich sequences—that is, function arises after, not before, the information problem has been solved.
For this reason, invoking pre-biotic natural selection in an RNA World does not solve the problem of the origin of genetic information; it merely presupposes a solution to the problem in the form of a hypothetical but necessarily information-rich RNA molecule capable of copying itself. As Nobel laureate Christian de Duve has noted, postulations of pre-biotic natural selection typically fail because they “need information which implies they have to presuppose what is to be explained in the first place.”
Third, the capacity for even partial replication of genetic information in RNA molecules results from the activity of chemists, that is, from the intelligence of the “ribozyme engineers” who design and select the features of these (partial) RNA replicators. These experiments not only demonstrate that even highly limited forms of RNA self-replication depend upon information-rich RNA molecules, they inadvertently lend additional support to the hypothesis that intelligent design is the only known cause by which functional information arises.
STEPHEN C. MEYER, Ph.D. Cantab
Author, Signature in the Cell
Senior Research Fellow, Discovery Institute
Seattle, Washington, U.S.A.