Replication or Metabolism??

Understanding the origin of life in the universe is certainly crucial to astrobiology, unfortunately there are many gaps in the early biological history of life on earth. In my astrobiology class, we discussed how geological processes on early earth must have changed to biological processes at some point, but in our earliest fossil record of life, we find bacteria/archaea, without any explanation for how these organisms developped in the harsh abiotic environment.

Our class examined arguments for both metabolism-first and replication-first hypotheses. Some camps believe either rudimentary metabolic or primitive chemical reactions started on their own and eventually enclosed in an organism some time later. In class, I arrived at the conclusion that these processes must have occurred simultaneously, however low the probability may be, it seems to me that some metabolic molecule could form peptides that change from generation to generation, eeking into both roles.

Are there some bid assumptions here?