Which was the origin, DNA, RNA or Protein?

For an overall view, wikipedia would be a good place to start.
http://en.wikipedia.org/wiki/Abiogenesis

It tells about many other models besides the RNA World Hypothesis and there are plenty of resources at the bottom of the page. Note however that there is no universally accepted theory on abiogenesis.

I went to this article and found this - 2nd paragraph -

"Most amino acids, often called "the building blocks of life", can form via natural chemical reactions unrelated to life, as demonstrated in the Miller–Urey experiment and similar experiments that involved simulating some of the hypothetical conditions of the early Earth in a laboratory.[1] Other equally fundamental biochemicals, such as nucleotides and saccharides can arise in similar ways."

Does anyone object to the use of "most"?

I actually conducted a reduced form Miller - Urey in 1969 and find the use of "most" to be excessive.

To understand more fully how amino acid composition of proteins has changed over the course of evolution, a method has been developed for estimating the composition of proteins in an ancestral genome. Estimates are based upon the composition of conserved residues in descendant sequences and empirical knowledge of the relative probability of conservation of various amino acids. Simulations are used to model and correct for errors in the estimates. The method was used to infer the amino acid composition of a large protein set in the Last Universal Ancestor (LUA) of all extant species. Relative to the modern protein set, LUA proteins were found to be generally richer in those amino acids that are believed to have been most abundant in the prebiotic environment and poorer in those amino acids that are believed to have been unavailable or scarce. It is proposed that the inferred amino acid composition of proteins in the LUA probably reflects historical events in the establishment of the genetic code.

Using our approach, we have estimated the amino acid composition of a set of 65 proteins within the LUA. We infer that within this set of proteins many of the amino acids believed to have been most abundant in the prebiotic environment (Miller 1953<$REFLINK> , 1987<$REFLINK> ; Kvenvolden et al. 1970<$REFLINK> ), including glycine, alanine, aspartic acid, and valine, were used more frequently within proteins of the LUA than within those of modern species. On the other hand, amino acids believed to have been rare or unavailable prebiotically, including cysteine, tryptophan, tyrosine, and phenylalanine, were generally used much less frequently within proteins of the LUA. This may reflect the order of addition of these two groups of amino acids to the genetic code.

The modern ribosome was largely formed at the time of the last common ancestor, LUCA. Hence its earliest origins likely lie in the RNA world. Central to its development were RNAs that spawned the modern tRNAs and a symmetrical region deep within the large ribosomal RNA, (rRNA), where the peptidyl transferase reaction occurs. To understand pre-LUCA developments, it is argued that events that are coupled in time are especially useful if one can infer a likely order in which they occurred. Using such timing events, the relative age of various proteins and individual regions within the large rRNA are inferred. An examination of the properties of modern ribosomes strongly suggests that the initial peptides made by the primitive ribosomes were likely enriched for l-amino acids, but did not completely exclude d-amino acids. This has implications for the nature of peptides made by the first ribosomes. From the perspective of ribosome origins, the immediate question regarding coding is when did it arise rather than how did the assignments evolve. The modern ribosome is very dynamic with tRNAs moving in and out and the mRNA moving relative to the ribosome. These movements may have become possible as a result of the addition of a template to hold the tRNAs. That template would subsequently become the mRNA, thereby allowing the evolution of the code and making an RNA genome useful. Finally, a highly speculative timeline of major events in ribosome history is presented and possible future directions discussed.

Some riboswitches and their ligands may be relics of signaling networks
used when organisms relied on RNA instead of DNA and proteins.

ompelling evidence supports the hypothesis that modern cells descended from organisms whose components were made entirely of RNA. Scientists who helped formulate this “RNA World” hypothesis for the evolution of life have identified many characteristics of modern cells that strongly suggest RNA once ruled the planet. For example, the existence of self-cleaving and self-splicing ribozymes that cut and ligate RNAs demonstrates that at least some RNA-processing reactions can be catalyzed without the need for proteins. Also, the existence of ribosomal RNAs that build all genetically encoded proteins emphasizes the fact that today’s organisms depend on RNA to carry out fundamental biochemical processes. Even many nucleotide-like coenzymes that are near universal in all life forms likely first appeared in RNA World organisms. The RNA World hypothesis is appealing because it helps explain the arcane characteristics of genetic and biochemical processes in modern cells. Why do all cells use ribosomal RNAs, and not protein enzymes, to stitch together amino acids to make polypeptides? Most likely, the ribosome’s peptidyl transferase center is an evolutionary descendent of an ancient ribozyme that first catalyzed this reaction before protein enzymes evolved. Why do so many coenzymes, such as adenosylcobalamin (AdoCbl), thiamin pyrophosphate (TPP), flavin mononucleotide (FMN), S-adenosylmethionine (SAM), molybdenum cofactor (Moco), and tetrahydrofolate (THF), all carry recognizable fragments of RNA nucleotides or derive from nucleotide precursors? Perhaps these compounds served as coenzymes for metabolic ribozymes of the RNA World, and they have been preserved as legacies from a time before protein enzymes existed.