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The history - Spontaneous human combustion is not a recent phenomenon. It was first reported in 1470, when an Italian knight named Polonus Vorstius allegedly burst up in flames.

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A knight's tale - But the case was not officially recorded until Danish physician Thomas Bartholin included it in his book of rare conditions, 'Historiarum Anatomicarum Rariorum,' almost two centuries later.

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"Act of God" -

In 1725, a man was charged with the murder of his wife, Nicole Millet, but was acquitted after a surgeon's testimony. The court decided it was a case of SHC, and an "act of God."

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Italian countess - In 1731, an Italian countess also became known as a victim of SHC. More cases followed, including that of an Englishman in 1744.

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Alcohol in the mix -

All cases had one common denominator: alcohol consumption. The scientific community became intrigued and decided to investigate further.

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Theory -

A theory was put forward in the journal 'The Philosophical Transactions of the Royal Society of London' that gases and intestinal waste mixed with alcohol made these people spontaneously ignite.

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Charles Dickens - Charles Dickens' novel 'Bleak House' included a case of SHC in its plot, adding weight to the public's belief of the phenomenon in the 1800s.

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Critique - But philosopher and literature critic George Lewes wasn't a fan. He wrote in a newspaper that 'Bleak House' gave "credence to a scientific impossibility."

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Mary Reeser - In 1951, 67-year-old widow Mary Reeser died in her apartment in St. Petersburg, Florida, supposedly of SHC.

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Media attention - The case hit the media, and the lack of evidence made it sound quite mysterious.

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FBI - Years later, it came to light that the FBI found that Mary Reeser didn't die of SHC.

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Jack Angel - In 1974, traveling salesman Jack Angel claimed to have survived spontaneously combusting.

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Survivor - He explained that he had woken up to burns on his hand, chest, and legs, among other areas.

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Debunked? -

But skeptic and investigator of the paranormal Joe Nickell describes in 'Real-Life X-Files: Investigating the Paranormal' that Angel was actually burned by hot water.

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Michael Faherty - In 2010, 76-year-old Michael Faherty burned to death at home in Galway, Ireland. The case was eerily similar to earlier supposed SHC cases.

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Modern SHC case confirmed -

Coroner Dr. Ciaran McLoughlin ultimately attributed Michael Faherty's death to SHC.

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The facts -

Indeed, for a human body to be cremated, it takes a temperature somewhere between 1400 and 1800°F (approximately 760 to 982°C).

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How are bodies reduced to ash? - And this is what actually happens in SHC cases, where bodies are reduced to ashes, except for hands and feet, which are found intact most of the time.

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Surroundings intact - In SHC cases, the person's surroundings also often remain intact. So, how can these combustion cases be explained?

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Explanation - A theory put forward called the "wick effect" may answer this question.

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Wick effect - The theory supposes that a body can burn to ashes using its own fat as fuel.

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Fat-free -

This explains how a body can burn for hours and yet have the hands and feet intact, as they're virtually fat free.

According to the wick theory, a heat source such as cigarette ash is enough to pierce the skin and initiate the burning process.

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Pig experiment - Pig tissue, being similar to a human's in fat content, was used in experiments by Dr. John de Haan of the California Criminalistic Institute to prove the wick theory.

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Ketosis? - Here's another theory: researcher Brian J. Ford suggests that higher acetone levels are to blame, which can happen when the body is in a state of ketosis.

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Acetone - When the body is starved of glucose, it starts using fat (ketones) as fuel. This in turn produces acetone, which is highly flammable.

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Ball lightning - Another theory points to ball lightning as a cause for humans to ignite. This unexplained phenomenon consists of floating spheres of lightning. Individuals tend to report seeing these when thunderstorms are nearby.

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Stevens-Johnson syndrome -

Stevens-Johnson syndrome is a rare allergic reaction that can cause burns and blisters. As a result, it has also been listed as a potential explanation for SHC (although it doesn't burn people completely).

See also: Ghost stories: celebrities reveal their paranormal experiences.

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