Final answer:
The fight-or-flight response to stress was first described by Walter Cannon. It prepares the body to either confront (fight) or avoid (flight) a stressor, which is crucial for survival. Hans Selye contributed with his findings on the general adaptation syndrome, a separate but related concept.
Step-by-step explanation:
The fight-or-flight response to stress was first described by Walter Cannon, a Harvard physiologist, in the early 20th century. Cannon identified the body's physiological reactions to stress and viewed the fight-or-flight response as an adaptive mechanism that enables individuals to adjust internally and externally to threats, thereby ensuring their survival. It is a sympathetic nervous system response that prepares the body to either confront or flee from a stressor, increasing heart rate and energy levels to cope with the situation.
Hans Selye, another significant figure in the study of stress, discovered the general adaptation syndrome, which is the body's nonspecific physiological response to stress, but this is separate from Cannon's concept of fight-or-flight. The term fight-or-flight has evolved over time, and recent research also considers the physical and psychological consequences of this stress response in modern life, where it may not always be as adaptive as it once was for survival.