Guinea Pig

In 1822, on an island in Lake Huron, a young French-Canadian voyageur named Alexis St Martin was accidentally shot in the side at close range. He was not expected to live. He did, and the wound healed in a way that left a permanent opening from the outside world directly into his stomach, covered by a flap of tissue that could be pushed aside. The army surgeon who had treated him, William Beaumont, realised what he had: a window into a living digestive system, at a time when digestion was still argued about as though it might be a kind of putrefaction or a kind of grinding.

Beaumont dangled pieces of food on silk threads through the hole and pulled them out at intervals to see what had happened to them. He drew off gastric juice and tested it in glasses. He established, more or less single-handedly, that digestion is a chemical process performed by a secreted acid, which is one of the foundational facts of physiology. He also, when St Martin went home to Canada and showed no enthusiasm for coming back, pursued him for years, and eventually had him sign articles of indenture: St Martin agreed to serve as Beaumont's servant and to submit to his experiments, in exchange for board and a modest sum. The experiments ran to a couple of hundred. The relationship, by every account including their own letters, was one of intermittent resentment on both sides.

St Martin outlived Beaumont by nearly thirty years. When he died, his family — who had spent his whole life fending off requests for access to him — are said to have deliberately let the body decompose before burial and then interred it unusually deep, specifically to stop anyone performing an autopsy. Whatever one thinks of the science, that detail tells you exactly what it had been like to be the subject of it.

from How to Think Seriously About Superheroes (2026)