Your blood type is not just A, B, AB, or O. This video explores the hidden history of blood type, Karl Landsteiner's ABO discovery, the older humoral system of constitutional medicine, the Flexner Report, disease risk by blood group, Rh-negative blood, and why modern medicine may have reduced blood to a simpler classification.

For nearly two thousand years, physicians believed blood revealed far more than transfusion compatibility. From Hippocrates and Galen to Avicenna, medicine classified people by constitution, temperament, and inherited disease vulnerability. Sanguine, choleric, melancholic, phlegmatic. This was not fringe belief. It was the dominant medical framework across Europe and the Islamic world for centuries.

Then in 1901, Karl Landsteiner's discovery of the ABO blood group system changed medicine forever. Safe blood transfusion became possible, but something else happened too. The older constitutional model of blood and disease was swept aside during the same era that the Flexner Report standardized American medicine, shut down alternative medical schools, and replaced individualized medical philosophies with a narrower biomedical system.

This documentary examines whether modern medicine simplified blood for practical reasons while discarding older ways of reading disease susceptibility, lineage, and human difference. It follows the path from humoral theory to Landsteiner, from the Rockefeller medical network to World War I blood studies, from malaria and cholera selection pressure to Basque Rh-negative blood frequencies that still raise unanswered questions.

Modern research now shows that blood type is not just about transfusion. Type O reduces severe malaria risk. Type A, B, and AB carry different disease associations. Forty-eight blood group systems exist, yet most people are told almost nothing beyond a single letter on a card. So what was lost when blood became a classification instead of a story?

This is the buried history of blood types, constitutional medicine, ABO groups, Rh-negative populations, and the standardized medical system that may tell you less about yourself than older physicians once tried to understand.