 The squealing pig experiment was when Galen would cut open a pig, and while it was squealing he would cut the nerve, or vocal cords, showing they controlled the making of sound.His anatomical reports remained uncontested until 1543, when printed descriptions and illustrations of human dissections were published in the seminal work "De humani corporis fabrica" by Andreas Vesalius where Galen's physiological theory was accommodated to these new observations.Galen's theory of the physiology of the circulatory system remained unchallenged until ca.