Bird Evolution?

Dr Jackson,
I remember reading how evolutionists say that a reptile developed wings by trying to catch flying insects, and in the process their scales wore out , this being the first step to change into feathers.My question is: I thought that mutations was the only mechanism for change, that most, not all evolutions believe in.Warn out scales is not mutations, and when their offspring are born they will have normal scales.Or, 4,000 years of Jewish circumcision should by now eliminated the need to circumcise.So why should they use that story which is not using any mechanism to change the genes?
dominic.