Each May in some northern Greek villages revelers walk barefoot across a bed of burning wood coals as part of a three-day celebration in honor of Saint Constantine and Saint Helen.

"They believe that the power of Saint Constantine—the religious power—allows them to do it and that that is a miracle," said Loring Danforth, an anthropologist at Bates College in Lewiston, Maine.

The festival is just one of the many events around the world in which people walk across a fire pit without getting burned.

Danforth has extensively studied fire-walking rituals, including the event in northern Greece and the more recently established fire-walking movement in the U.S.

As interest in fire walking has grown, he said, scientists have attempted to demystify the phenomenon and