I thought this was worth opening a new thread. It's the same subject we have discussed before but dhw wants an expert to explain things to us At the bottom of this site there is a video series of a lecture by John Maynard Smith at the Royal Institution which explains a lot of things very simply so that even I could understand it.-http://humanistheritage.org.uk/articles/john-maynard-smith/-Recommended. Without going into the actual chemical structure of proteins and bases he explains how the biological code works and also puts forward a theory about how it could have evolved.