Purpose: This is a review of a review paper by C. de Sousa, Life As Cosmic Imperative? Phil. Trans. R. Soc. A (2011) 369, 620–623 doi:10.1098/rsta.2010.0312, and more generally, a concept known as “chemical selection.”
What is critical and central in the review paper (but more importantly to the field of chemical-origin-of-life science) is the use of “natural selection” as an underlying methodology, and if we assume that the “selection” invoked in this paper is the same interpretation of natural selection used in Cristian de Sousa’s and others, then I believe it raises new questions about what selection theory actually is. In the contexts that de Sousa and many other references (Lehninger 1980) have used it, selection is a theoretical and as yet, unproven chemical concept. It is invoked as a physical concept which in de Sousa’s words is the following:
“Selection is different. Originally formulated by Darwin as the mechanism of
evolution of reproducing living organisms, natural selection also affects replicating
molecules such as RNA, as first shown by Spiegelman  and since repeated
in a variety of ways by many investigators. In both cases, the essence of the
process lies in the imperfections of reproduction. For all sorts of reasons, whenever
entities are replicated, variants of the original model are inevitably produced.
Selection acts on those variants to automatically bring out those that are most
stable and, especially, most capable of producing progeny, under the prevailing
conditions. AND…” Natural selection acts blindly on the products of chance. It has no foresight.”
“The first stage depended exclusively on chemistry. The second stage likewise involved chemistry, but with the additional participation of selection, a necessary concomitant of inevitable replication accidents.”
Stage II? What kind of chemical physics is this meant to be? De Sousa has no evidence for any chemical species copying themselves in nature, that is, outside of molecules derived from already extant life. A key differentiation, since his hypothesis asserts that it Stage I, “it was all chemistry”. This does not occur outside of cells, and has only been shown artificially in laboratories (i.e. PCR, rtPCR), but when these tests are done correctly they produce a negative. Should we also expect that since natural selection is falsifiable chemically it cannot be reproduced in nature, that the model of this paper also based on the same “natural selection” should meet the same burden and has been falsified by contrary laboratory results, again those actually simulating natural conditions?
If “chemical selection” is indeed a real testable theory or mechanism, as it is cited many times in peer reviewed literature, such as these, then can it be falsified? In other words, what is it about ANY chemical reaction that one can envision, that would proceed differently, WITH or WIHOUT so called the mechanisms described as natural “chemical selection?” I say that if you cannot answer that question, it does not pass muster for science. We may apply this simple test to those cases where it is claimed that “self-replication” has been confirmed in vitro, asking how the confirmed case differs from the non-confirmed case and the chemical difference(s) expected in each.
De Sousa states: “Up to this event, only chemical reactions were involved”. ..and “After
it occurred, selection was added to chemistry.” We are then to understand that something, was “added to chemistry.” And we wish to know what that something might be. If so, if one claims that this additional property exists in some cases, but not in others, how would you show that it is falsifiable? Would we expect…X…behavior of chemistry? Whatever X might be, a new reaction which selects itself towards, products? Let us write A+C-à D+E and demonstrate one example, only one, in which the chemical species proceed toward products D and E by this alleged process called “natural chemical selection.” Is there one example in all of the literature that answers this question? Again, whereby there is as he claims, a stage I and stage II. And again, de Sousa is echoing in a review, the generalized belief that this is a real phenomena. As with any real phenomena there must be falsifiable conditions, theoretical or actual, proposed in order to verify its existence. This is only one of the aspects of my objections to this paper, the other is outlined below and is more theoretical.