Final answer:
The earliest symptom of inflammation is typically pain. It, along with redness, swelling, warmth, and possible loss of function, is caused by the body's innate immune response to injury or infection.
Step-by-step explanation:
The first symptom of inflammation is often pain, which is accompanied by other symptoms such as redness, swelling, warmth, and sometimes loss of function. These signs are part of the body's innate immune defense and are triggered by increased blood flow, the movement of leukocytes, and the release of chemicals to the site of injury or infection. The inflammatory response not only signals an issue in the body but also sets the process for tissue repair and defense against pathogens. Cornelius Celsus, a Roman scholar, first documented these signs during the Roman Empire in the first century AD.