Its from here:Not that I don't believe you but what you mind telling me where that information came from? I have always had natives cause their own extinction when I tried to play as a tolerant colonizing power. There are bonuses to not killing them that makes me want the option to exist; but my understanding is they force your hand like in EU3. I am glad to be wrong however if I am.
Its from here:
http://forum.paradoxplaza.com/forum...IV-Developer-diary-34-Unit-Interface-and-more
"Attack Natives cost 5 MP, and is the only way to possibliy eliminate them, as defeating them in a normal uprising does not work anymore."
- A large native presence increase the amount of trade a colony produces, offsetting costs..