Jesuit's bark

Quinine, the first effective treatment for malaria, came from Peruvian tree bark brought to Europe by Jesuit missionaries in the 1630s. The bark of the cinchona tree—called "Jesuit's bark" or "Peruvian bark"—contained an alkaloid that killed the malaria parasite, enabling European expansion into tropical regions that had previously been death traps.

Indigenous peoples of the Andes had used cinchona bark medicinally, though exactly for what conditions remains unclear. Spanish colonizers learned of its properties; Jesuits, with their extensive networks in the Americas, brought samples and knowledge back to Rome. By the 1640s, Jesuit's bark was being used to treat fevers in Italy and spreading through European medical practice.

The mechanism remained mysterious for two centuries. Malaria was attributed to "bad air" (mal aria) from swamps; the bark seemed to work against the mysterious fever without anyone understanding why. Pierre Joseph Pelletier and Joseph Bienaimé Caventou isolated quinine from the bark in 1820, enabling standardized dosing and eventually synthetic production.

Colonial implications were enormous. Malaria had killed more European colonizers than any enemy. With quinine prophylaxis, Europeans could survive in Africa, Southeast Asia, and other tropical regions long enough to establish permanent settlements. The scramble for Africa in the late 19th century was chemically enabled by quinine.

The cinchona tree remained the sole source of quinine until World War II, when Japanese conquest of Southeast Asian plantations forced development of synthetic alternatives. Chloroquine and other antimalarials eventually reduced quinine's importance, though drug-resistant malaria strains have renewed interest in quinine-based treatments.

A tree bark from Peru, carried by Jesuits, transformed both medicine and empire. The adjacent possible for tropical colonization required this specific chemical that happened to exist in a specific Andean tree.