10. Barry Marshall
Back in 2006, Barry Marshall and a colleague chose to infect themselves with the bacteria Helicobacter pylori in an effort to identify the cause of stomach ulcers. While it’s widely believed that ulcers are caused by lifestyle choices in the medical community, Marshall was convinced bacteria was to blame. Of course, he chose himself as a human test subject, going behind the backs of the hospital’s ethics committee and his wife.
According to Marshall, the first three days were smooth sailing, despite his wife claiming his breath was horrid. However, after ten days he began to vomit violently and a biopsy revealed that he had gastritis from the bacteria, which will eventually evolve into ulcers. Proving his theory would take another eight years before it was accepted by the medical community, but Marshall believes the trial and error was worth it.