But, the positive deterioration we create for ourselves is catastrophically negative for many other species. A companion concept to environmental deterioration is societal collapse. Previously for the entire Pleistocene there were large shifts in climate on the scale of centuries to millennia, cause by volcanic eruptions. Native American civilizations experienced more or less the same as in other places. After 1492, however, disease was the single most important reasons for the collapses of Native American civilizations and for their devolution to simpler forms of social organization based on greatly reduced populations and loss of knowledge.
People always talk about tribes at a certain time, but never about tribes changing through time.
Disease was the only reason that Europeans conquered the new world. Native Americans did not die from diseases because they were weak, but because they had no immunity and because different diseases came one after another. Make a transition to the impact of disease. The Genetical Theory of Natural Selection. Flohn, H. On the time scales and causes of abrupt paleoclimate events.