> "...there has to have some advantage at some level even if it isn't obvious at all." I don't think 'natural selection' makes a bidirectional claim in this wa

> "...there has to have some advantage at some level even if it isn't obvious at all." I don't think 'natural selection' makes a bidirectional claim in this way. Not every gene expression is an advantageous mutation. In other words, a lot hinges on your interpretation of 'advantage'. Darwin's observations of advantage explained difference, whereas a mutation which leads to similar traits in organisms would not have an advantage per se--it's just mutation, replication, selection. repeat. This is not my field of study. Maybe someone else can correct me or say this better...