Final answer:
Native Americans were severely affected by disease outbreaks because they had no immunity to European diseases, leading to mortality rates as high as 90 percent and a devastating impact on their societies.
Step-by-step explanation:
Impact of Diseases on Native Americans
During the rise of the natives, several issues profoundly affected them, but disease outbreaks were particularly catastrophic. The reason diseases like smallpox affected Native Americans so severely was primarily that the Indigenous peoples had never been exposed to the infectious diseases originating in European domesticated animals, leading to no immunity against these diseases. The introduction of European diseases to Native American populations resulted in widespread epidemics which are estimated to have caused the death of up to 90 percent of these populations.
This lack of prior exposure to diseases such as smallpox, measles, typhus, and cholera meant that European diseases decimated native populations. It wasn't just the infections themselves but the subsequent implications for their societies that were devastating. The high mortality rates among the very young and old led to a loss of future generations, knowledge, and traditions, which only compounded the trauma and made resistance to European conquest and colonization exceedingly difficult.