In the 1930's, with traffic fatalities becoming a growing public health concern, manufacturers began to explore the design of safer cars. But the new science of crash testing raised a seemingly intractable problem: to study the effect of a crash on the human body, researchers would have to equip the test car with a live human being. Volunteers were few.
As a result, the first crash-test dummies were cadavers. While useful in collecting basic data, they lacked the durability required for repeated trials.
And because no two cadavers were exactly the same size and shape, no two tests were strictly comparable.
Actually, cadavers are still used in some crash tests today, as I learned from chapter 4 of Mary Roach's incredibly enjoyable book "Stiff: The Curious Lives of Human Cadavers."