Mann does pick the most optimistic ranges of estimates to try to paint a particular narrative, but he is also very frank that he is doing that, and he repeats this fact several times throughout the book. It would be wonderful if more books were willing to do that sort of guarding to emphasize how much the evidence really supports the thesis. Considering that pre-Columbian America tends to get the short-end of the stick in history, I'm willing to tolerate the constant pushing on the narrative to help emphasize that the popular view of pre-Columbian American is more often incorrect to correct.