Final answer:
Smallpox arrived in Australia and decimated the Aboriginal population due to diseases brought by European settlers. The lack of previous exposure or immunity to smallpox resulted in rapid spread and devastating consequences.
Step-by-step explanation:
The evidence suggests that Smallpox arrived in Australia and decimated the Aboriginal population due to the arrival of European settlers. The Europeans brought diseases like smallpox, influenza, measles, and typhus to the New World. While Europeans had developed resistance to these diseases, the Native Americans had no immunity.
In the case of Australia, it is believed that the British colonizers brought smallpox to the continent. As the Aboriginal population had no previous exposure or immunity to the disease, it spread rapidly and caused devastating consequences.
It is estimated that around 80 percent of the indigenous population in the Americas perished due to diseases brought by Europeans. Smallpox alone caused a significant decline in population. For example, in Hispaniola, the population dropped from 5 million to 500 in just 25 years after Columbus landed.