Octors and researchers have made serious advances in medicine, allowing them to better understand how the human body works and how to treat illness. This knowledge results from the process of , one of the main causes of social change.

This knowledge results from the process of DISCOVERY.

Explanation: Discovery can be referred to as  the act of finding or learning something for the first time. It is the act of revealing something more like a revelation. Discovery is one of the main causes of social change which is the significant change of cultures and norms in the society.

"Serious advances" can be referred to as change or significant change, exactly what discovery illustrates.