Over at the blog Jesus Creed, RJS writes:
DNA is capable of passing information on from generation to generation – but it is not reactive and requires a complex series of reactions involving proteins for replication. Production of these proteins of require both RNA and additional proteins for transcription, and translation. The interrelated reactions are quite complex. DNA is a fairly stable (unreactive) molecule, making it good for information storage, but the chemistry of DNA is simply not rich enough for life to originate from DNA.
Proteins have a very rich chemistry and can perform many functions. But they are not capable of replication. There are no specific interactions that allow one amino acid chain to produce an identical chain.
Therefore – life did not originate with proteins, nor did it originate with DNA.
What RJS presents is the classic, foundational argument for the RNA world:
- DNA is inert, but it passes on information across time.
- Proteins don’t pass on information across time, but are reactive.
- RNA is both reactive and passes on information across time.
- Since life requires both reactivity and the ability to transmit information, life must have started with RNA.
But it’s not a simple as this.