I agree with @adrianN (impact correlates to population density) with the obvious caveat that the real question is the ratio between the rate of removal and the

I agree with @adrianN (impact correlates to population density) with the obvious caveat that the real question is the ratio between the rate of removal and the rate of replacement. In my initial post when I said prehistoric practices were not sustainable, I should have qualified it -- "not ALL prehistoric practices were sustainable." If you live on an island eating moa, a few thousand of you can drive a species to extinction.