From the Author's Abstract, Page ii-iii:
"It is evident from the past forty years of research, debate and literature that the New World was far more populated in 1492 than was previously thought. However, despite the expanding field of study most works omit the effects that epidemics had on the tribes of the Great Plains, particularly those located in present-day Canada, and the works that have been published deal mainly with demographics and fail to delve into how disease affected intertribal relations. As well, almost all studies of disease and the Great Plains tribes end by 1850 or start in 1880 . Therefore, the decades from 1860 through to the 1870s are largely ignored and become even more of a mystery when considering the fact that the eventual subjugation of the Plains Natives soon came when the Numbered Treaties commenced in 1871.
The omission of research on epidemics from 1860 to 1880 has left historians to concentrate on other reasons for the collapse of the Plains lifestyle, primarily the disappearance of the buffalo, which was crucial to Native existence in the parkland/grassland regions . Although this was obviously a very important factor in weakening warrior societies on the Plains, it was by no means the sole factor. In fact, the smallpox epidemic of 1870-71 and its after effects played an important role in debilitating Native nations, especially great tribes like the Plains Cree in present-day Saskatchewan . Food supplies could not be maintained and starvation became prevalent throughout the Great Plains in the winter of 1870-71 . Malnutrition certainly would also have led to further secondary complications such as fertility problems and pulmonary illnesses, such as pneumonia, which would have contributed to the impact of the epidemic through a continued loss of population and disruption of intertribal functioning. Through analysis of the consequences of this epidemic on the Plains Cree it becomes increasingly apparent that disease played a much greater role in leading Natives towards treaty negotiations and settlement than has been formerly thought . This is not to say that epidemics in themselves were the main reason for the collapse of the Plains Cree culture, but rather they deserve to be included along with the traditional causes such as the disappearance of the buffalo." (ii-iii).
Brain, Rebecca Lee Barbara. "Invisible Demons: Epidemic Disease and the Plains Cree: 1670-1880." University of Saskatchewan, 2002.