The development of the ribosome would seem to be a key watershed event in the evolution of life, bridging the gap between RNA (and possibly DNA, haven't heard anything definitive on that) world and the development of prokaryotic life... the critical point at which proteins came into play in the reactions of organic molecules.

 

I don't know if we have any clues as to what the structures from which ribosomes evolved were originally used for, but I would like to know how much ribosomes have evolved since the progenotes gave way to the first bona fide prokaryotic cell. Do ribosomes really change all that much throughout time, or is thier function so critical that a mutation in the genes which code for ribosomes would doom a cell to death?

 

Did life begin harnessing protein before the ribosome? Might the ribosome have evolved to aid an already developed but slow and poorly orchestrated protein assembly process?

Do ribosomes really change all that much throughout time, or is thier function so critical that a mutation in the genes which code for ribosomes would doom a cell to death?

They certainly change, but not alot in a structural sense. Eukaryotes and prokaryote ribosomes are somewhat different in form. Prokaryote ribosomes tend to translate faster than eukaryote (I think roughly 10 aa's per second as opposed to 4). In addition, the mitochondria have their own ribosome that translates the handful of genes on the mitochondria. So there's clearly been change of the ribosome over time, but it's not as dramatic as the change you'll see in, say transcriptional processes (although that may be more due to the evolution of regulatory processes that occur with transcription).

 

Did life begin harnessing protein before the ribosome?

I don't knowm but at the least there needed to be readily available amino acids.