an RNA world would need to be the offspring of some earlier life process
I disagree and challenge you to prove this. RNA is a simpler chemical than DNA, and would be quite capable of being synthesized in a random chemical environment. But even this is not necessary to abiogenesis; you might want to have a look at autocatalytic sets. They are a much more likely explanation of the origin of life on Earth, IMO, than any other; and you will also find that they are a very, very hard target. Particularly since it appears that scientists working for chemical companies have used the ideas behind autocatalytic sets to successfully create (evolve! Note most carefully!) enzymes for various uses, like odor elimination, stain removal, drain clog removal, and other purposes. These enzymes work extremely well. To top it all off, the theory of autocatalytic sets accounts for RNA, too!
It is worthwhile also to point out that templates for the synthesis of proteins are not nearly as limited as many believe. In fact, out of many, many millions or even billions of candidate amino acids, life here on Earth uses only a very, very few. For example, in your body, all of the proteins generated by your DNA are made from only twenty amino acids, out of these billions. These twenty amino acids are coded for by combinations of only four nucleotides in groups of three. You will note that four codons, taken three at a time, gives sixty-four possible combinations; with "start" and "stop" codons, and redundant combinations, this allows the specification of literally trillions of possible proteins, enough to permit an immune response to just about any antigen you will encounter in your lifetime. You should know (would, if you'd do the research) that your immune system does not come pre-programmed to combat diseases; instead, it comes pre-equipped with a "toolkit" of antibody-generating cells that are- have to be!- capable of adapting to and attacking any organism that invades your body. Given the rapid mutation rate of viruses and bacteria, this is an absolute requirement for you to be a robust organism yourself; if you were limited to only the organisms that could be specified in your DNA, you would quickly die on being exposed to a novel virus or bacterium, and this would probably happen in your first year of life.
But those four nucleotides, and those twenty amino acids, are by no means the only ones possible; in fact, there are millions or billions of others, plus combinations and permutations of them, that many believe would yield a viable genetic code, and a viable "toolkit" of proteins it can construct. In fact, alternate genetic codes actually exist on Earth; mitochondria, ciliate protozoa,
Mycoplasma, and some yeasts of genus
Candida use differing interpretations for at least some codons, hinting that alternate codes may have been dominant in the past.
The question is not, and never has been, "How did this incredibly unlikely genetic code come to be." It is not unlikely; it is instead inevitable. Obvious. Expected. Once, that is, one knows the laws of physics and complexity that govern chemistry. The question at hand is rather, "Of all the possible choices, why did evolution on Earth settle on the particular genetic code it did?" And the answers to that increasingly appear to have to do with robust replication, and robust correction of point mutations. It becomes increasingly obvious that the particular genetic code we use has also been subject to selection pressures. That it has itself evolved. Representations of a genetic code that must necessarily have sprung fully-fledged from nothing are therefore revealed as misrepresentations of the actual state of affairs: we see that the genetic code has evolved, and that other genetic codes are possible; given a billion years or so, and all the world's oceans, with the obvious results of the Miller-Urey experiment in hand, we can see that it is inevitable that life should have developed here.
In any case, the original point was that both genetics and memetics are accurate descriptions of reality on some level. And while I will give you points for at least presenting what you see as an alternative, I also have to point out (although I did not do the detailed critique wowbagger did, I did read it) that both alternatives appear to be relatively unaffected by whether genes preceeded proteins, or succeeded them. It is likely that we will never know for sure; it is equally likely that we will create at some point organisms that have all the necessary attributes for us to call them "living" that do not use the same genetic code we do. And I ask you, will they be "alive," will they be "life," whatever that might mean?
Underlying this conversation is the following point: the meaning of the genetic code is undeniable. We can duplicate most of the functions
in vitro. And given that that meaning, the clear, unambiguous mapping between genes and proteins, is unquestioned, the utility of DNA as a blueprint for the creation of proteins, and as the source of the repetition of arrangement of proteins and their actions that we call ontogeny.
Given this known paradigm, and given the complexity with which an organized collection of proteins can act, it must be obvious that there is something that can be acted upon, that can be inherited, that is the source of all our phenotypes. And this must be the place where all changes that can be inherited must come from. And no matter what went before, once this DNA mechanism became dominant in life on Earth, it must be what ultimately is changed whenever a heritable phenotypical change occurs in a population of organisms. It does not matter what other chemical or physical changes occur in an organism; if the DNA, and specifically in the germ plasm, is not changed, then that change is not heritable. And conversely, it does not matter what is changed in germ plasm,
that change
will be heritable,
even if it makes no difference whatsoever to the phenotype of the organism. These are provable facts, and have been proven over and over again; the mere existence of genetically modified organisms is undisputable proof that when evolution occurs in modern life forms, and by modern I mean anything that uses DNA on Earth, which is every organism alive on Earth today, and just about every organism that has lived since the beginning of the Cambrian.
Given that such a mechanism exists, it has to be obvious that there can be no question as to what changes when evolution occurs. Thee can be only one answer. It must be DNA. Nothing else answers the obvious requirement for something that can be inherited, something that determines the phenotype, and something that is both difficult enough to change that it is usable for transmission of phenotypical characteristics, and easy enough to change that it can be that which changes when evolution occurs.
In this low-level sense, then, genetics does not map well to memetics. However, I have to point out that once you posit evolution of chemicals, and point out the similarities to genetic evolution, you have inadvertently made an analogy that improves the viability of memetics, because the way memes evolve is much more like the way that you posit that chemicals evolve prebiotically than the way that we know DNA evolves. Unlike genes, memes are themselves the phenotype; they are the ideas themselves, not "genes of ideas," as would be required by strict analogy with genetic molecular biology.
