The difference between evolution and devolution isn't always clear to me. Sometimes moving forward means returning to a previous state, perhaps one better suited to the current environment. On the other hand, devolution doesn't necessarily require retrograde motion; it's possible to move forward without gain. Lossless motion can occur in either direction, but motion doesn't always improve things. Sometimes it just musses your hair.
It's confusing. Sure, I can change my DNA as easily as the next guy, but what if I don't want to look like him? What if I like my ears right where they are? Just because something is possible, that doesn't automatically make it beneficial, especially when it comes to ears, or fingers. Maybe you think it would be cool to have feathers instead of fingers, because that way you could flap around the room like some kind of demented bird, and all your friends would call you up and invite you to parties.
Only you couldn't hear them because you need at least one ear for that sort of thing. That's all I'm really trying to get across here.