Is spontaneous human combustion possible?

Question

An article from Ireland dated January, 2011 shows that spontaneous human combustion (SHC) remains a hot topic among paranormalists.

Spontaneous human combustion has been defined as:

Spontaneous human combustion (SHC) is the alleged burning of a person's body without a readily apparent, identifiable external source of ignition. The combustion may result in simple burns and blisters to the skin, smoking, or a complete incineration of the body. The latter is the form most often 'recognized' as SHC. source

Proponents also claim that cases of SHC may require an explanation outside that provided by science because:

• Even the skeleton is reduced to ashes, which does not happen even in crematory ovens.
• Damage is localized almost entirely to the victim, often leaving even the nearby area untouched
• The burns to the victim appear inconsistent, as the lower legs and hands are often found after the rest of the body has been incinerated.

A quick serach of Amazon shows there are quite a few books written on SHC. Most of these books posit varying ideas for the mechanism which could be underlying the phenomenon.

In "Ablaze", Larry Arnold posits the existence of an entirely new particle called the "pyroton" which he claims may be responsible for the phenomenon.

However, there are many theories which range from outright magic to paranormal to pseudoscientific to scientific.

Some of the more popular theories include:

• Static flash fires - the same mechanism behind gas station fires.
• Alcoholism - First popularized by Dickens in "Bleak House" is the idea that excess alcohol consumption somehow makes the human body more flammable
• Electrical fields - somehow, the body's electrical system becomes the source of either the initial spark or the resultant fire, possibly induced by so-called "mitochondrial explosions" resulting from oxidative phosphorylation.
• External sources - Suggesting that the fire may be started by an outside source, usually tobacco ash.
• An unusually high susceptibility to either beta or gamma radiation.
• Ball Lightning - The very existence of ball lightning itself is controversial.

Of the 200 or so claimed cases of SHC, some of the more popularly referenced ones include:

• Mary Reeser 1951
• Maybelle Andrews 1938
• Billy Peterson 1958
• Dr. John Bentley 1966

A list of other cases can found here.

While I have included some modern names and dates for reference, cases are cited as far back as 1731 (Countess de Bandi Cesanate) and 1673 (Case report by John Henry Cohausen).

Is there a known process at work in SHC or does it remain unexplained?

Has SHC ever been scientifically studied or replicated under proper observing conditions?

Answer 1

Spontaneous Human Combustion does not exist.

Mark Benecke, a forensic biologist, has researched this topic extensively.

His remarks have been published in National Geographic, The Daily Telegraph and BBC, among others. He has written a lengthy, well-sourced report for the Skeptic Inquirer which seems to cover the topic conclusively.

To quote the relevant bits (emphasis mine):

The pictures and reports published on SHC up to now can be explained by well-known and understood mechanisms that are regularly found at the sites of burning. There is no need to invent bizarre chemical reactions or paranormal activities to explain what is mistakenly called "spontaneous combustion."

and,

In forensic practice, there are no known cases in which internal organs of a burned corpse were damaged more severely than the outer parts. This practical observation is further proof that combustion never starts from inside a human body.

He also mentions the multiple wick effect to account for the partial burning of just the clothed parts of a body:

Items of clothing act as multiple wicks and support burning over a long time because the body fat in subcutaneous layers changes into a liquid form.

Proponents of SHC have the facts wrong.

He also debunks some of the claims made by proponents of SHC which try to undermine conventional explanations (again, emphasis mine):

[A proponent of SHC] seems to be under the illusion that [hydrogen and oxygen] exist as gases in the cell and are thus vulnerable to ignition, which is, in fact, not the case.

…

The main objection that supporters of SHC have to such ordinary explanations is that they doubt that the course of an event can be demonstrated in retrospect, especially in cases of burning. This is not true.

…

Articles arguing for SHC often state that local temperatures in excess of 1,500°C are necessary to produce the "typical picture" of alleged SHC. Again, this is nor true.

Proponents of SHC distort the evidence.

It is also worth noting that many SHC reports are false or incomplete:

Many photographs of alleged SHC appear to have fooled observers by not showing the complete remains of the bodies as found in situ […]

This readily explains claims made by SHC proponents, that (as the OP said):

• Even the skeleton is reduced to ashes, which does not happen even in crematory ovens.
• Damage is localized almost entirely to the victim, often leaving even the nearby area untouched
• The burns to the victim appear inconsistent, as the lower legs and hands are often found after the rest of the body has been incinerated.

It seems, then, that these claims are false or highly exaggerated.