What is one reason Indians were vulnerable to European diseases?

Question

Quizplus · Accepted Answer

Indians were vulnerable to European diseases primarily because they had not been exposed to the pathogens of domesticated animals, unlike Europeans. Europeans lived in close proximity to domesticated animals like cows, pigs, and chickens, which over centuries led to the transmission of various diseases to humans, building immunity in the European population. Native Americans, relying more on hunting and gathering or small-scale agriculture without these domesticated animals, did not develop immunity to these diseases, making them particularly susceptible when Europeans arrived with animals and diseases to which the natives had no prior exposure.

What Is One Reason Indians Were Vulnerable to European Diseases