Many years after completing the Beagle voyage, crafting the theory of natural selection and writing the most famous scientific tome of all time, Charles Darwin took up psychology.In fact, Darwin performed what may be the world's first study of how people interpret and understand the emotions of others, according to a paper published in the April issue of the Journal of the History of the Neurosciences.The experiment originated from a disagreement between Darwin and French neurologist G.B.A Duchenne. Duchenne believed that every emotion expressed on a person's face is created by a separate muscle. To support this, he went about the grim task of electrically stimulating participants' facial muscles and photographing the resulting expression, ultimately producing a set of 65 different plates.Read more at...SFARI, May 2010.