Well, you'll have to explain to me how a detailed analysis of the kai genes across a large number of species of cyanobacteria, proteobacteria, and archaei, showing that their interrelationships have the form of a tree, and how that tree has a very similar structure to the tree obtained by examining relationships between the genes for a completely different molecule, the 16S RNA, is a 'just-so' story.
To help you, here are the two trees. Enjoy.
Fascinating Professor. I have never seen the evolutionary tree for bacteria, but say, does it represent ALL known types? Or just the ones under discussion? Where's gonorrhea, streptococcus, nitrogen-fixing soil bacteria, etc. on the tree? I was under the impression that cyanobacteria had been assigned their own separate kingdom.