Final answer:
Eurasian diseases like smallpox and measles introduced by Europeans led to devastating soil epidemics in New World populations, causing mortality rates of up to 90% and massive population declines.
Step-by-step explanation:
The Eurasian diseases had a catastrophic impact on New World populations. The introduction of diseases such as smallpox, influenza, measles, and typhus by European conquerors led to soil epidemics, a term referring to the devastating outbreaks that occur when a disease enters a population with no previous exposure or immunity. Native American communities suffered mortality rates up to 90 percent, a far more severe impact compared to the Black Death in Europe and Asia. The lack of immunity in indigenous populations resulted in massive population declines, with some areas like Hispaniola experiencing a reduction from over a million people to merely 500 in just 50 years. Such rapid and extensive loss of life had profound effects on societal structure, knowledge, and continuity for the Native American people.