A groundbreaking study from Yale University's Ancient Pharmacology Program reveals that Roman Emperor Caligula, notorious for his cruelty and erratic behavior, possessed sophisticated knowledge of medicinal plants and ancient pharmacology. The research, published in the Proceedings of the European Academy of Sciences and Arts, challenges long-held assumptions about the infamous ruler by demonstrating his deep understanding of hellebore treatments and Roman medical practices.
The study, led by research scientist Andrew Koh and associate professor Trevor Luke, examined a brief anecdote recorded by the historian Suetonius about Caligula's encounter with a Roman senator seeking medical treatment. Their analysis reveals that beneath the emperor's reputation for madness lay a surprisingly comprehensive grasp of ancient medicine, particularly the therapeutic uses of the flowering plant hellebore.
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Ancient Medical Tourism and the Hellebore Connection
The Yale research focuses on a story originally reported by Suetonius in "The Twelve Caesars," where an unnamed Roman senator of praetorian rank sought medical treatment in the Greek spa town of Antikyra. This small port town on the Gulf of Corinth had gained fame throughout the Roman Empire for its specialized hellebore treatments, which were believed to cure epilepsy, mental illness, and various other ailments.
When the senator requested an extension of his medical leave, Caligula's response was both cruel and revealing. The emperor had the senator executed, quipping that "a bloodletting was necessary for one whom hellebore had not benefited in all that time." While this anecdote has long been cited as evidence of Caligula's capricious cruelty, the Yale researchers argue it demonstrates something far more significant: the emperor's detailed knowledge of ancient medical practices.
Historical botanical illustration of Helleborus niger (black hellebore), one of the medicinal plants used in ancient treatments (Public Domain)
"Our work suggests that Antikyra functioned as a kind of Mayo Clinic of the Roman world — a place where affluent and influential Romans visited for medical treatments not widely available elsewhere," explained Andrew Koh, principal investigator of the Yale Ancient Pharmacology Program. "It also provides evidence that Caligula, while a tyrant, was more knowledgeable about medicine than has been previously understood," quotes a Yale release.
Ancient texts describe two varieties of hellebore used in Roman medicine: white hellebore for treating afflictions of the head and black hellebore for clearing the bowels. The researchers discovered that hellebore didn't grow in sufficient quantities around Antikyra itself, with the closest large reserves located more than 2,500 feet above sea level on Mount Helicon's southern slopes.
The Emperor's Personal Medical Interests
The study reveals that Caligula's medical knowledge likely stemmed from personal necessity rather than mere academic interest. Historical sources indicate that the emperor suffered from epilepsy, insomnia, and mental distress — precisely the conditions that ancient physicians believed hellebore could treat. This personal connection to the ailments hellebore supposedly cured may have motivated his detailed study of the plant's properties and applications.
Caligula's reference to bloodletting in his cruel jest about the senator suggests he had read the medical treatise De Medicina by Celsus, which was composed during the reign of his predecessor Tiberius. This work prescribed bloodletting as an alternative treatment to hellebore for epilepsy, indicating that Caligula was familiar with contemporary medical literature and competing therapeutic approaches.
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Researchers will analyze the phytochemicals in plant specimens they recently collected from the Greek landscape to test their efficacy in relation to their ancient reputations. (Photo courtesy of YAPP)
The philosopher Philo of Alexandria, one of Caligula's most prominent critics, commented on how the emperor "distorted Apollo's art of medicine for malicious purposes," suggesting that even his detractors acknowledged his pharmacological expertise. This observation gains new significance when considered alongside the Yale findings, as it indicates that Caligula's medical knowledge was substantial enough to be noted by contemporary intellectuals.
Reframing Historical Narratives
The research challenges traditional interpretations of Caligula's character by suggesting that his apparent madness coexisted with genuine intellectual capabilities. While not seeking to rehabilitate the emperor's reputation, the scholars demonstrate that he possessed practical knowledge extending beyond his notorious cruelty, including understanding of trade routes, seamanship, and now, ancient medicine.
"It's possible that Suetonius is wrong, and that Caligula wasn't ordering the man's execution but simply prescribing an alternative treatment that he had read about or knew from his own experience," suggested Trevor Luke, co-author of the study.
"We're presenting a more complete and well-rounded version of Caligula as a ruler who was in tune with the medical wisdom of his day."
The study also sheds light on the broader phenomenon of medical tourism in the ancient world. Roman elites regularly traveled to specialized treatment centers like Antikyra, much as wealthy individuals today might visit renowned medical institutions. This pattern of seeking cutting-edge treatments abroad demonstrates the sophistication of Roman medical networks and the empire's integration of Greek medical knowledge.
Modern view of Antikyra, the ancient Greek spa town where Roman elites sought hellebore treatments (Yale Ancient Pharmacology Program)
Implications for Understanding Ancient Medicine
The Yale researchers are now conducting phytochemical analysis of hellebore specimens collected from the Greek landscape to test their efficacy and biochemical interactions. This scientific approach combines textual evidence with empirical research to better understand ancient medical practices and their potential modern applications.
The findings contribute to a growing body of research that challenges oversimplified historical narratives about ancient rulers. By examining primary sources through interdisciplinary lenses combining history, archaeology, and pharmacology, scholars can develop more nuanced understandings of complex historical figures.
The study also highlights the importance of ancient medicinal knowledge and its potential relevance to modern medicine. As researchers continue to explore traditional remedies for new therapeutic applications, understanding the historical context and original uses of ancient treatments becomes increasingly valuable for contemporary medical research.
Top image: Roman marble bust of Emperor Caligula from the Carlsberg Glyptotek collection, showing the notorious emperor who possessed surprising medical knowledge according to new research. Source: CC BY SA 2.0
By Gary Manners
References
Cummings, M., July 2025. Was Caligula a madman? Maybe. But he also knew his medicine, scholars find. Yale News Available at: https://news.yale.edu/2025/07/09/was-caligula-madman-maybe-he-also-knew-his-medicine-scholars-find
Koh, A. & Luke, T. (2025). Antikyran hellebore in the time of Caligula. Available at: https://www.peasa.eu/site/article/view/56
