Here is how I understand it:
DNA replication is not 100% perfect and error can happen, this error can be good(evolution) or bad(cancer properties). But its not the only source of cancer cells - DNA can be damaged by environment, and in rare cases it can receive cancer properties.
Am I correct?
this error can be good(evolution) or bad(cancer properties)suggests some misunderstanding about what evolution is about. – Remi.b Mar 25 '16 at 02:38