“He would subject them to extreme temperatures, make them go hungry for long periods, or make them exercise a lot,” the medical historian Mark Jackson says. “Then what he would do is kill the rats and look at their organs.”
What was interesting to Selye was that no matter how different the tortures he devised for the rats were — from icy winds to painful injections — when he cut them open to examine their guts it appeared that the physical effects of his different tortures were always the same.
“Almost universally these rats showed a particular set of signs,” Jackson says. “There would be changes particularly in the adrenal gland. So Selye began to suggest that subjecting an animal to prolonged stress led to tissue changes and physiological changes with the release of certain hormones, that would then cause disease and ultimately the death of the animal.”
And so the idea of stress — and its potential costs to the body — was born.
But here’s the thing: The idea of stress wasn’t born to just any parent. It was born to Selye, a scientist absolutely determined to make the concept of stress an international sensation.