350 Years Ago, A Doctor Performed the First Human Blood Transfusion. A Sheep Was Involved

Early scientists thought that the perceived qualities of an animal—a lamb’s purity, for instance—could be transmitted to humans in blood form

Although scientific discoveries about blood started happening in the seventeeth century, blood transfusions are (mostly) a twentieth-century thing. iStock

Blood: humans need it to live, but the wrong sort is very, very deadly.

On this day in 1667, a prominent French physician named Jean-Baptiste Denys performed the first documented blood transfusion to a human. His hapless subject, an unnamed 15-year-old boy, had been bled to promote his health—so much that he was suffering from blood loss. Writing for Wired, Tony Long points out that the transfusion was a little different than those performed in modern hospitals. “He used a sheep’s blood,” writes Long. “And, somehow, the kid survived.”

The boy didn’t get better because of the sheep’s blood, which was likely administered in a negligible quantity—the only reason he didn’t die. Nor did the butcher who Denys subsequently performed the experiment on. Human blood and sheep’s blood aren’t compatible. Human blood is frequently not even compatible with other human blood. What happens next should be obvious: The scientist, emboldened by the apparent success of early experiments, killed someone. But the story is a bit more complicated than that.

That someone was named Antoine Mauroy, a mentally ill man who was well known in Paris. Denys and his colleagues wondered if performing a transfusion on Mauroy might “cure” him, by replacing his bad blood with good. And rather than transfusing blood from a (likely unwilling) and certainly impure human, they picked a calf. They thought that transfusing the blood of an animal that seemed innocent and pure, they might be able to counteract the things in the man's own blood that were making him act badly.

Mauroy died—although, writes medical historian Holly Tucker, of arsenic poisoning by competing surgeons. But he did survive a first and even a second transfusion.

“Only five or six ounces of calf blood made it into the man,” she writes. “Yet Mauroy began to sweat profusely: his arm and both armpits were burning hot.” Frightened by this reaction, which is now known to be produced by the body’s white blood cells attacking the unfamiliar blood in much the same way as they attack a disease, the doctors stopped what they were doing. They tried again the next day, and perceived that the man seemed more docile and less “mad.”

The third time, though, the inevitable happened. The outcome was a subsequent trial in which Denys was found not responsible for the death. Arsenic, a known poison, was the culprit, not transfusion. But the French court banned transfusion all the same. “For some, the risk that science could create monsters—or worse, corrupt the entire human race with foreign blood—was simply too much to bear,” Tucker writes.

After Denys’ experiments and some failed experiments later the same year in England, no member of the mainstream scientific community attempted to do it again until the nineteenth century. Given that blood transfusion between most different human blood groups (which were not discovered until 1900) or humans and animals is extremely deadly, it’s just as well.

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