Darrin McMahon is a historian who studies how cultures change over time. He looks at things like what people believed in different eras, how ideas were spread and how people lived their lives. He also looks at how governments and societies change from one period to the next. He uses books and other sources to learn more about the past, and he sometimes travels to places where he can see things for himself. Darrin's work helps people understand how the world has changed over time.