What was a significant factor in the susceptibility of Indigenous people to European diseases?

The susceptibility of Indigenous people to European diseases can largely be attributed to the lack of prior exposure to those diseases. This population had not encountered many of the infections brought over by Europeans, such as smallpox and influenza, which had been prevalent in Europe for centuries. As a result, their immune systems had not been exposed to these pathogens and did not have the necessary adaptations or acquired immunity to effectively combat them.

Prior exposure to similar diseases often leads to a population developing some level of immunity over generations. In contrast, the Indigenous populations, isolated from these diseases for thousands of years, lacked this protective factor. This absence of previous exposure significantly increased their vulnerability to the devastating impacts of the diseases introduced by European colonizers.