Science  /  Origin Story

How Transatlantic Slave Trade Shaped Epidemiology Today

Slave ships and colonial plantations created environments that enabled doctors to study how diseases spread.

Since the outbreak of COVID-19, many have been frustrated by the ways in which the Centers for Disease Control and Prevention (CDC) keeps changing its rules and response to the pandemic. What most don’t understand is that the field of epidemiology is always like that. Protocols about how to control an epidemic mostly develop in the middle of crises. But those crises have not only been of the medical variety, and knowing more about that history provides an important lesson for those living through the pandemic today.

In fact, many of the tools that we are using to control the pandemic—observation, surveillance and data collection—developed not from scientific inquiry in isolated laboratories, but rather as urgent responses to crises that arose due to the transatlantic slave trade and the expansion of the British empire. That troubling past is a reminder of how medical advances can occur on the backs of human beings with no say in the matter.

Slavery and imperialism both led to unprecedented social arrangements that congregated people into crowded environments where they were under constant surveillance. Although military and government officials established surveillance mechanisms to subjugate these populations, doctors were also part of these regimes and began to observe the spread of infectious disease. Slave ships and colonial plantations emerged as new environments that enabled doctors to study epidemics. Their investigations happened just as medical knowledge in general was undergoing a transformation. Doctors began to move away from the idea that supernatural forces produced epidemics and began to turn to how environments caused the spread of infectious diseases.

Most histories trace the development of epidemiology to London in the mid-19th century when physician John Snow ventured into a poor neighborhood in Victorian London to investigate a cholera outbreak. By collecting data of various patients and observing their daily practices, Snow eventually traced the disease’s spread to a water pump in the center of the neighborhood. He expanded the role of the physician from a healer to a detective. By observing the cholera outbreak in real time, Snow was able to control it. He subsequently became lauded as the “Father of Epidemiology.”

But this label is not entirely accurate. Snow was part of the London Epidemiological Society, which included a group of physicians who had, out of necessity, become investigators of global epidemics. The doctors who served on slave ships, colonial regimes and throughout the empire became the first epidemiologists. The tools to manage the empire—record keeping, surveillance, and observation—have also, by no coincidence, become the major tools that epidemiologists depend on today.