Mooney, Kroeber, et al. didn't yet have enough information to make
accurate estimates. There is a recent book, carefully documented and
totally depressing, called "American Indian Holocaust and Survival," by
Russell Thornton, which has far more awful figures on the devastation of
European diseases on native Americans. It is necessary to look at the big
picture (north AND South America) to get the extent of the devastation,
and also to put it into historical context: that is, Europeans brought
the diseases but not with any understanding of microbes, and they died in
droves themselves from them, and had endured many pestilential wipeouts in
Europe in earlier years (Black Plague, etc.) There were some examples of
direct attempts to infect some tribes with smallpox, but for the most part
the diseases were spread by trade goods, contact, and sadly enough, sweat
baths, which in cases of some diseases, made things worse. The tribes had
been wholly unexposed to these diseases, and therefore had no immunity.
When they got sick, they had no antibodies to fight with, as a result, and
they tended to catch the strange diseases more easily, become sicker
faster, and had a much higher mortality rate than Europeans. Some
unofficial estimates I did for early New England indicate that in some
areas there was a total mortality in some Indian towns (the Pilgrims
settled in just such a town: Patuxet, which became Plymouth.) Others, over
a period of 20 years, say, lost upwards of 95% of their populations. John
Smith sailed along Cape Cod on years and reported seeing, "Great troops of
well proportioned people." 2 years later, after a terrible epidemic in the
1600's, he sailed along the same area and saw no one, and abandoned
houses and fields. I have tried to imagine the social chaos that must
have resulted from epidemics like these, and it boggles the mind. The
Indian people alive today are all descendants of the survivors of those
times, and no doubt are biologically a select group.