Is there any consensus about what was going on during the 'dancing plagues' of the middle ages, particularly in Strasbourg in 1518? What are the major theories about it?

There is no major consensus on the cause of the “dancing plagues,” and several theories have been proposed over the years. I’ll start with the main responses by Strasbourg and then move to some of the other theories that have developed since.

Humoral imbalance: City physicians in Strasbourg initially diagnosed the dancers with hot blood and recommended more dancing to cure them. The city hired musicians and created dance spaces in markets and guild halls and worked to keep the choreomaniacs dancing continuously to rebalance their humors. This approach didn’t work, though, so the city eventually prohibited music and moved on to religious approaches.

Demonic possession or curse: In many earlier instances of dance mania (especially in 1374), medieval people believed a curse or demon possession to be the cause and used exorcism as a cure. The dancing was often called St. John’s disease or St. Vitus’s disease, two saints who were commonly associated with the curse. St. Vitus became more popular in the 15th century, as he became the patron saint of epilepsy, plague victims, musicians, and dancers. There was a shrine to St. Vitus not too far from Strasbourg, and many of the Strasbourg dancers were cured through a pilgrimage to the site. Demonic possession continued to be a popular theory for ecstatic dancing throughout the early modern period, especially within witchcraft discourse.

Mania /hysteria: The majority of theories about the dancing plague stem from medical discourse stretching all the way back to the 16th century. Paracelsus, writing in the 1520s, refuted the demonic possession theory. Instead, he proposed that the dancing was caused by climatic changes that affected people’s vitals. People were inclined to move based on mental imaginings and “laughing veins” that spread a “ticklish feeling” throughout the body and deprived the mind of reason. Medical discourse continued to develop neurological or psychological causes, linking the dancing plagues with epilepsy, mental disorders, and spastic movements (chorea). Dancing plague discourse became really popular in the 19th century. J. F. C. Hecker published Epidemics in the Middle Ages, which included an essay on “The Dancing Mania”. Hecker largely sensationalized the event and understood the dancing plagues as a kind of epidemic mental disorder related to hysteria. He believed that the phenomena originated in ancient Greece or Rome and recurred in the medieval period due to the physical and mental stress of the Black Death pandemic. A lot of Hecker’s ideas are tied up in ideas of the medieval period as a pre-rational, pre-modern world, and the dancing plagues as episodes where people lost all form of reason. Jacques Le Goff argued that the dancing was a form of mental illness and that malnutrition and other physical stress from plague-time would have primed medieval people for hallucinations (Gotman 2018, 53).

John Waller most recently expanded on the theory of hysteria, arguing that the dancing plague “was a pathological expression of desperation and pious fear,” which could have only occurred in a culture invested in supernaturalism (Waller 2008, 13). He focuses on the extraordinarily harsh conditions of plague and famine, general outcry for religious reform, and failed peasant revolts as underlying causes of the distress, and he argues that past instances of dancing plagues provided a template for how hysteria could manifest. People believed they could be cursed to dance by St. Vitus, and so the only way to cure their dancing was through religious ceremony that would appease the saint. Waller believes that the dancers were in a trance-like state, which allowed them to dance for extended times without noticing their full physical exhaustion and pain. However, because Europe did not have a prominent trance tradition that would include codified ways to enter and leave a trance, the dancers had no clear model of how to stop their trances, making the condition especially terrifying. Waller postulates that the weakening of saint cults after the Reformation and shifts away from supernaturalism towards scientific belief ultimately brought an end to dancing plagues.

Ergot poisoning: Ergot poisoning is another common theory that emerged in scientific discourse, especially by Eugène Louis Backman, a pharmacologist. Among the many symptoms of ergotism are body spasms. John Waller (and others) largely discredit this theory because the afflicted choreomaniacs were regularly described as dancing, implying some kind of sustained and rhythmical movement, not just body spasms. The chronicles also do not mention other prominent symptoms of ergot poisoning, like gangrene.

Anti-Dance/Anti-Jewish discourse: Kélina Gotman suggests that some instances of dance mania could have been targeted attacks on dance practices seen as disruptive to the social order or originating from outsiders. She notes accusations of paganism or demonism during dance festivities at the feast of St. John and general suspicion of Jewish and foreign dances. Migrations by marginalized groups like Jews and Roma could account for reports in the 1370s that choreomaniacs were nomadic groups that moved from town to town.

Devotion: Kathryn Dickason, a medieval dance and religious scholar, proposes that choreomania was actually a practice of trance devotion that was part of larger ecstatic and spectacular dance practices of the late medieval period. She notes how choreomanics sometimes saw visions of heaven or performed their own exorcisms on each other, which allowed them to sidestep the authority of priests, whom they accused of corruption.

Performance: Michael Lueger views the episodes as conservative movements during times of societal distress and political unrest that sought to return to traditional cultural institutions. He agrees with Dickason and Waller that the dancers were probably in a trance state. He reads the episodes as following more of a “script” with the 1374 and the 1518 dancing plagues ending with similar rituals that invited an intervention from a group of authority. In both cases, the choreomaniacs were demanding their clergy to demonstrate spiritual guidance, which would require clergy to be more attentive to their laity’s needs and move away from corruptive practices. If considered as a performance, the dancing outwardly demonstrated the choreomaniacs’ feelings of lacking spiritual guidance.