%0 Historical Article %T Mobile Monkeys and Modified Microbes: Medical Experimentation between Metropolitan and Colonial Laboratories, 1880-ca. 1925. %A Sunseri T %J Bull Hist Med %V 98 %N 1 %D 2024 %M 38881469 %F 0.659 %R 10.1353/bhm.2024.a929783 %X Following the medical breakthroughs of Pasteur and Koch after 1880, the use of simians became pivotal to laboratory research to develop vaccines and cultivate microbes through the technique of serial passage. These innovations fueled research on multiple diseases and unleashed a demand for simians, which died easily in captivity. European and American colonial expansion facilitated a burgeoning market for laboratory animals that intensified hunting for live animals. This demand created novel opportunities for disease transfers and viral recombinations as simians of different species were confined in precarious settings. As laboratories moved into the colonies for research into a variety of diseases, notably syphilis, sleeping sickness, and malaria, the simian market was intensified. While researchers expected that colonial laboratories offered more natural environments than their metropolitan affiliates, amassing apes, people, microbes, and insects at close quarters instead created unnatural conditions that may have facilitated the spread of undetectable diseases.