Why did Native Americans change their ways of life?

Native Americans had to adapt to survive, and they did so in a number of ways, life changed dramatically and became much for the worse for Native Americans after the arrival of the Europeans. First, the Native American population was rapidly reduced by the introduction of European diseases for which the people had no immunity, such as smallpox, cholera, bubonic plague, and whooping cough. Some estimates run as high as a ninety percent mortality rate among some tribes-a devastating figure

. Explanation:

Some estimates run as high as a ninety percent mortality rate among some tribes-a devastating figure