Spontaneous Human Combustion

­In December 1966, the body of 92-year-old Dr. J. Irvin­g Bentley was discovered in his Pennsylvania home by a meter reader. Actually, only part of Dr. Bentley's leg and slippered foot were found. The rest of his body had been burned to ashes. A hole in the bathroom floor was the only evidence of the fire that had killed him; the rest of the house remained perfectly intact.

How could a man catch fire -- with no apparent source of a spark or flame -- and then burn so completely without igniting anything around him? Dr. Bentley's case and several hundred others like it have been labeled "spontaneous human combustion" (SHC). Although he and other victims of the phenomenon burned almost completely, their surroundings, and even sometimes their clothes, remained virtually untouched.

Can humans spontaneously burst into flames? A lot of people think spontaneous human combustion is a real occurrence, but most scientists aren't convinced.

What is Spontaneous Human Combustion?

Spontaneous combustion occurs when an object -- in the case of spontaneous human combustion, a person -- bursts into flame from a chemical reaction within, apparently without being ignited by an external heat source.

The first known account of spontaneous human combustion came from the Danish anatomist Thomas Bartholin in 1663, who described how a woman in Paris "went up in ashes and smoke" while she was sleeping. The straw mattress on which she slept was unmarred by the fire. In 1673, a Frenchman named Jonas Dupont published a collection of spontaneous combustion cases in his work "De Incendiis Corporis Humani Spontaneis."

The hundreds of spontaneous human combustion accounts since that time have followed a similar pattern: The victim is almost completely consumed, usually inside his or her home. Coroners at the scene have sometimes noted a sweet, smoky smell in the room where the incident occurred.

What makes the charred bodies in the photos of spontaneous human combustion so peculiar is that the extremities often remain intact. Although the torso and head are charred beyond recognition, the hands, feet, and/or part of the legs may be unburned. Also, the room around the person shows little or no signs of a fire, aside from a greasy residue that is sometimes left on furniture and walls. In rare cases, the internal organs of a victim remain untouched while the outside of the body is charred.

Not all spontaneous human combustion victims simply burst into flames. Some develop strange burns on their body which have no obvious source, or emanate smoke from their body when no fire is present. And not every person who has caught fire has died -- a small percentage of people have actually survived what has been called their spontaneous combustion.

The Theories

To combust, a human body needs two things: intensely high heat and a flammable substance. Under normal circumstances, our bodies contain neither, but some scientists over the last several centuries have speculated on a few possible explanations for the occurrence.

In the 1800s, Charles Dickens ignited great interest in spontaneous human combustion by using it to kill off a character in his novel "Bleak House." The character, named Krook, was an alcoholic, following the belief at the time that spontaneous human combustion was caused by excessive amounts of alcohol in the body.

Today, there are several theories. One of the most popular proposes that the fire is sparked when methane (a flammable gas produced when plants decompose) builds up in the intestines and is ignited by enzymes (proteins in the body that act as catalysts to induce and speed up chemical reactions). Yet most victims of spontaneous human combustion suffer greater damage to the outside of their body than to their internal organs, which seems to go against this theory.

Other theories speculate that the fire begins as a result of a buildup of static electricity inside the body or from an external geomagnetic force exerted on the body. A self-proclaimed expert on spontaneous human combustion, Larry Arnold, has suggested that the phenomenon is the work of a new subatomic particle called a pyroton, which he says interacts with cells to create a mini-explosion. But no scientific evidence proves the existence of this particle.

So far no one has offered scientific proof of a theory explaining spontaneous human combustion. If humans can't spontaneously combust, then what is the explanation for the stories and pictures of people who have seemingly burned from within?