Researched
Epidemiology
Counting who falls ill, where and why: John Snow's 1854 cholera map founded the science of how diseases spread in populations.
Open in the interactive tree →In 1854 John Snow mapped cholera deaths in London's Soho and traced them to the Broad Street water pump, years before germs were accepted as the cause. Kermack and McKendrick's 1927 model described how epidemics grow and fade, and Doll and Hill's 1950 study linked smoking to lung cancer. Outbreak tracking, vaccination policy and pandemic planning all build on epidemiology.
Prerequisites
- Earth measurement and maps~240 BCSnow's cholera analysis was a dot map of deaths
- Probability Theory1654
- Statistics & Least Squares1809Snow's cholera analysis used the registered death statistics built up by William Farr
Unlocks
- Sewers and clean water1858
- Vitamins and deficiency diseases1747-1912
- Randomized controlled trial1948
- World Health Organization1948
- Smoking causes lung cancer1950
- Oral rehydration therapy1968-1971
- HIV identified1983
- COVID-19 pandemic2020
- WHO Pandemic Agreement2025The pandemic agreement relies on epidemiological surveillance of how disease spreads
- Pandemic preparednessopen