What makes us stronger

FOR centuries physicists have used the word stress to describe force applied to materials. It was not until the 1930s that Hans Selye, a Hungarian-born endocrinologist, began using it of live beings. Selye injected rats with cow hormones, exposed them to extreme temperatures and partially severed their spinal cords to prove that all these sorts of maltreatment affected the rodents in the same ways: they lost muscle tone, developed stomach ulcers and suffered immune-system failure. He used the word for both the abuse of the rats and the health effects. Later on, it started to be used for psychological suffering as well.