First, let's get all the Duchenne controversies out of the way. When Duchenne was looking for participants for his study, few people agreed to be the subjects. Although he claimed that the electric shock administered only a small amount of electricity and was not painful, it still caused uncomfortable facial spasms.
Experts also don't deem Duchenne's experiments very ethical because he allegedly used mental health patients. Some sources claim that his subjects were paid, but, allegedly, he also used the severed heads of executed criminals to carry out his research.
Some of his notes show that he didn't think very highly of his subjects. As you scroll through the photographs, you'll probably notice that there are five different people in total: a young girl, a young woman, an older woman, a young man, and an old man. The latter was his principal subject, and Duchenne described him as "an old, toothless, man, with a thin face, whose appearance, without being precisely ugly, was more or less nondescript" and whose "intelligence was limited."
The old man was possibly the best subject for Duchenne's experiment. He had a medical condition that meant he had very little feeling in his face. Therefore, he didn't feel as uncomfortable with the electricity-induced facial spasms. His wrinkles also made him more expressive, allowing Duchenne to gauge and evaluate his expressions more clearly.
The young man is identified as Jules Talrich, an anatomist and anatomical modeler. Like his father, Talrich made wax and plaster anatomical models. He worked as a ceroplast at a university in Paris, but also had his own wax museum similar to our contemporary Madame Tussauds in London.
You can argue that Duchenne wasn't a good dude for using questionable tactics "in the name of science." But we can't deny that he's an influential figure in today's medical world. There are five neurological diseases named after him, and we refer to a true, genuine smile as a Duchenne smile.
How is it different from other smiles? A Duchenne smile is a facial expression that we humans recognize as an authentic expression of joy and happiness. Some call it the opposite of the "Pan Am smile," a forced, polite expression that is usually reserved for customers of service workers.
Experts describe a Duchenne smile as one that reaches your eyes, "making the corners wrinkle up with crow's feet." It requires us to use two facial muscles at once: the zygomaticus major muscle lifts the corners of our mouths, and the orbicularis oculi makes our eye corners wrinkle up and lifts our cheeks. Darwin and other researchers have since confirmed that the wrinkle at the eyes is what makes this kind of smile an expression of true joy.
In 2019, researchers found evidence that suggests the Duchenne smile can help us regulate our emotions. They studied individuals who felt ostracized in society, and found that a Duchenne smile helped them "spontaneously regulate their emotion experience" during stressful social encounters.
Another significant accomplishment of Guillaume Duchenne was the discovery of muscular dystrophy in the 1860s. The most common form of muscular dystrophy is even named after Duchenne. He was the first one to describe it, yet the gene that caused this wasn't discovered until the 1980s. Duchenne detailed the case of a boy who had the condition, and later wrote about 13 more cases of affected children. He was also the first one to do a biopsy of the patient's tissue and to examine it.
