Marshall drank a dish of bacteria himself since no ethics board would test it on patients

By the early 1980s, gastroenterologist Barry Marshall and pathologist Robin Warren had found a spiral bacterium, later named Helicobacter pylori, in the stomachs of nearly every ulcer patient they biopsied, and they suspected it was the actual cause of a disease the medical establishment attributed to stress, spicy food, and excess stomach acid.

Waiting for an animal model that might never work, or for a research establishment that didn't believe the hypothesis to fund human testing anyway, could have delayed proof for years, if it arrived at all, while ulcer patients kept being treated for stress instead of an infection. Marshall realized there was exactly one subject whose informed consent didn't require anyone else's approval: himself.

Marshall drank the bacteria himself, making himself both experimenter and subject, so no committee's consent was needed and the dramatic result proved causation.

The self-experiment works because it sidesteps the actual bottleneck, which wasn't scientific uncertainty but institutional risk-aversion: no committee has to approve exposing a subject to an unproven

It only produces a single data point, with all the statistical weakness that implies, and it works only for risks the experimenter can survive and is willing to accept — it offers no template for test

When the evidence that would change everyone's mind requires an experiment no ethics board, regulator, or investor will approve on someone else, check whether you're allowed to run that experiment on

The self-experiment produced undeniable proof; Marshall and Warren won the 2005 Nobel Prize in Medicine. Ulcers, once treated with lifelong acid-suppressing drugs and dietary restriction, are now routinely cured with a short course of antibiotics, a shift in standard of care directly traceable to Marshall's self-infection.