>>35
Just in case you are too lazy to google, here's just one of many, many historians:
"The first (factor) was the food supply... The second factor was disease. ...
A third factor, which strongly intensified the effect of the other two, was the social and physical disruption visited upon the Indian. He was driven from his home by the thousands, starved, beaten, raped, and murdered with impunity. He was not only given no assistance in the struggle against foreign diseases, but was prevented from adopting even the most elementary measures to secure his food, clothing, and shelter. The utter devastation caused by the white man was literally incredible, and not until the population figures are examined does the extent of the havoc become evident."
— Cook, 1976b, Population, page 200