Spontaneous human combustion (SHC) is the alleged occurrence where a person burns to death from a fire that has no external source of heat. Many cases of SHC have been reported over time, but a lack of eyewitnesses has led skeptics to believe that the phenomenon does not exist and that the cases can be explained by natural science.

A chronological sample of famous cases gives a snapshot of what these occurrences have in common and how they differ.

In 1663, it was reported that a woman in Paris burned to death while apparently asleep on her bed. Although she was mostly reduced to ashes, the straw mattress she was on did not burn. This is probably the first SHC case reported in modern scientific literature.

At some point around 1731 (dates differ), the Italian Countess Cornelia di Bandi went to bed and apparently got up in the middle of the night to open her bedroom window. Her remains were found the next morning as a pile of ashes in the middle of the floor with only her legs and three fingers remaining.

The remains of Mary Reeser, a suspected victim of spontaneous human combustionA more recent instance occurred when a Florida woman named Mary Reeser died from what some believe was SHC. On the evening of July 1, 1951, visitors left Reeser's apartment, leaving the elderly lady sitting in her easy chair smoking a cigarette. The following morning Reeser's landlady was delivering a telegram to Reeser's apartment and found the door handle too hot to open. Nearby workmen broke into the apartment, and they found the air in the apartment very warm and the easy chair burned to ashes. Next to the chair was a human leg still wearing a slipper, seen at right. Fire investigators said that a dropped cigarette could not cause a fire hot enough to cremate Reeser. There was no clear explanation, but months later law enforcement stated that a dropped cigarette had caused the fire.

In 1967, the remains of a homeless man were found in the shell of an abandoned building. Police at the scene of the fire reported that fire seemed to be coming out of the man's abdomen and that there was no external source of fire nearby.

In 1980, a 73-year-old Welsh man burned to death in his home. He legs remained unscorched, still enclosed in trousers and socks. Puzzled officials proclaimed the case as "death by burning" but did not cite a specific cause.

SHC has captured the imagination of many writers. Charles Dickens used it as a plot device in killing off a character in "Bleak House," and the phenomenon has been used in fiction by such notables as Herman Melville, Mark Twain and Washington Irving.

Over time, SHC entered the legal realm. In 1725, a man on trial for the burning death of his wife was acquitted when the defense successfully obtained a verdict of death due to SHC. In 2010, the suspicious death of an Irishman was legally declared to be caused by SHC after an investigation by the local coroner.

Scientists and skeptics have searched for a single cause for alleged cases of SHC. Pseudo-scientific theories in the past have included the wrath of God, sunspots, ball lightning, rogue bacteria in the digestive system, static electricity and undiscovered sub-atomic particles.

One formal scientific study at the California Criminalistics Institute burned a dead pig wrapped in a gasoline-soaked cloth and found that the end result strongly resembled known cases of SHC.

Other studies have postulated what is known as the "candle effect," where bodies set on fire by external means such as dropped cigarettes or fireplaces act like a candle, with the body's fat being the wax and the person's clothes acting as the wick.

Some skeptics have dismissed SHC entirely. Researcher Benjamin Radford questions why cases of SHC always seem to occur to lone humans indoors and often near sources of heat. Why, he asks, aren't there people spontaneously combusting while walking down the street? Another question is why SHC seems only to happen to humans—there are no reports of cats or horses or cows bursting into flame for no apparent reason.

The future will undoubtedly include more cases of SHC and further research will be done on those cases. Until then, SHC will continue to fascinate and be included in the mysteries of human existence.

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Primary source: "Ablaze!" by Larry E. Arnold.