It is obvious that chance mutations can help evolution advance, be neutral, or stop evolution's advance, with or wihtout natural selection. This is an elegent study on one protein as analyzed by Michael Behe. Don't be frightened. It all makes sense to me. I use all contributions from all sources to make up my mind:-http://behe.uncommondescent.com/2011/10/new-work-by-thorntons-group-supports-time-asymmetric-dollos-law/