USA HISTORY

Detailed explanation-1: -The short answer is that Europeans simply had more robust immune systems. Several factors contributed to this: first, Europeans had been the caretakers of domestic animals for thousands of years, and had over time grown (somewhat) immune to the common diseases that accompanied the domestication of such food sources.

Detailed explanation-2: -When the Europeans arrived, carrying germs which thrived in dense, semi-urban populations, the indigenous people of the Americas were effectively doomed. They had never experienced smallpox, measles or flu before, and the viruses tore through the continent, killing an estimated 90% of Native Americans.

Detailed explanation-3: -As Native peoples travel waterways by canoe to trade and share news, they unknowingly take the germs to neighboring tribes. Measles, mumps, chickenpox, smallpox, diphtheria, influenza, pneumonia, typhoid, and the common cold reach Florida and Cuba and begin their deadly march through populations across the hemisphere.

Detailed explanation-4: -Their relative isolation protected them from most infectious diseases. Conditions also must have been salubrious along the coasts of South Carolina and Southern California, as well as among the farming and hunting societies in what is now the Midwest.