This month, Smithsonian Magazine looks at the history of stigmata - when a faithful follower receives and suffers wounds or pain similar to those experienced by Christ on the cross (most commonly seen in the hands). The religious experience has been controversial amongst believers and non-believers alike, and science has been unable to pinpoint its cause or event agree on its existence.
In addition to claiming that the marks are divine gifts to the holy, skeptics have argued that cases of stigmata were hoaxes, symptoms of other diseases (including plague), or a form of hysteria. Even the Catholic Church is hesitant to discuss the issue (nearly all stigmatics are Catholic).
To learn more about the history of Stigmata, see the article on Smithsonian’s Blog: “The Mystery of the Five Wounds.”