Researchers at Yale University have utilized ancient DNA analysis to debunk centuries-old theories that Grand Duke Francesco I de' Medici, a Renaissance ruler of Tuscany, was poisoned. The study, published in the journal iScience, indicates that malaria was the most probable cause of his sudden death in 1587.
Francesco I de' Medici and his wife, Bianca Cappello, both died shortly after falling ill following a stay at a villa. This rapid succession of deaths fueled persistent rumors that they had been poisoned, with speculation often pointing to Francesco's brother and rival, Cardinal Ferdinando de' Medici.
However, analysis of DNA extracted from the rib bones of Francesco I de' Medici and his younger brother, Giovanni de' Medici, who died of malaria 25 years earlier, has provided new evidence. The research team, led by Serena Tucci, assistant professor of anthropology at Yale University, identified genetic traces of Plasmodium falciparum, the parasite responsible for the deadliest form of malaria, in Francesco's remains. Molecular traces of P. falciparum and a second species, P. malariae, were also found.
In Giovanni's remains, researchers discovered a novel strain of Plasmodium falciparum. This genetic confirmation of malaria in both brothers provides scientific proof to counter the persistent speculation about poisoning, which often involved theories of arsenic ingestion.
While historical accounts from contemporary court physicians described symptoms consistent with malaria, referred to at the time as "febbre terzana," the lack of definitive scientific evidence allowed poisoning theories to persist for centuries. Tucci noted that the historical reports, along with descriptions of treatments like bloodletting, align with malaria symptoms. She explained that the rumors likely continued because there was no conclusive scientific evidence until now to confirm a malaria diagnosis.
The study marks the first genetic analysis of the brothers' skeletal remains, confirming earlier suspicions based on historical records. While the researchers acknowledge they cannot definitively rule out poisoning, they state that malaria is the most likely explanation and that poisoning theories lack strong scientific support.
Beyond solving historical mysteries, the genetic approach used in this study could aid in understanding the evolution of malaria parasites. Gisella Caccone, a senior research scientist at Yale and co-author of the study, suggested that the recovered DNA, including the newly identified malaria strain, could help researchers develop better methods for controlling the disease. She stated, "Using historical specimens can not only help us understand our past better, but also it can help build a better future."