There actually may be some "research" that gives does not show "evidence" that there is no harm. However, there is plenty of research (real research) that shows there is plenty of harm. You only have to go back to Jeffrey Dahmer to see that there isn't even need for research.
And I love your account of how the Native Americans (your choice of words is so not politically correct - "Indians" indeed!) should have "expelled" the Puritans! I suppose you haven't heard that the people populating this part of the world before the Native Americans should have expelled them?