For centuries, people believed that Francesco I de' Medici was poisoned by his brother. The duke died in 1587, one day after his wife, and Ferdinando became the next ruler. However, a new DNA analysis shows that malaria caused his death. Researchers found the malaria parasiteparasite/ˈpærəsaɪt/L2寄生虫；寄生物a living thing that lives on or inside another living thing and gets food from it, often causing harm in his bones. They argue "with scientific certaintycertainty/ˈsɜːrtənti/L2确定性；确信the state of being completely sure about something" that disease, not poison, killed him.
The study also looked at another Medici brother, Giovanni. Researchers extractedextracted/ɪkˈstræktɪd/L2提取；取出to take something out, especially using a process or effort DNA from their rib bones. They found Plasmodium falciparum, the deadliest malaria parasite, in both brothers. This confirms historical accounts that said the brothers had fevers and other malaria symptoms. In addition, the analysis shows how ancient DNA can help map the history of this disease.
Rumors of poison started because Ferdinando was present at Francesco's deathbed. He also disliked Francesco's wife, Bianca. But the brothers had reconciledreconciled/ˈrekənsaɪld/L2和解；和好to become friendly with someone again after a disagreement two weeks before the death. As a result, the new evidenceevidence/ˈevɪdəns/L2证据；证明facts or information that show whether something is true or not clears Ferdinando's name. The study demonstrates that malaria was common in marshy areas where the Medici hunted.
