Natural Selection, unless you were born in a lab which would be unnatural/artificial, and not too likely with today's technology. (Maybe one day.)
Feathers are modified as scales. According to the history, birds which have feathers are the descendants of the dinosaurs which have scales.
That's why feathers are categorized as scales in the present record according to studies. <span />
Next you should analyze the data
It's the first one where it resist change in pH solutions by neutralizing :)
