Spontaneous human combustion (SHC) is a term encompassing reported cases of the combustion of a living (or very recently deceased) human body without an apparent external source of ignition. In addition to reported cases, examples of the phenomenon appear in literature, and both types have been observed to share common characteristics, regarding circumstances and remains of the victim.
Forensic investigations have attempted to analyze reported instances of SHC and have resulted in hypotheses regarding potential causes and mechanisms, including victim behavior and habits, alcohol consumption and proximity to potential sources of ignition, as well as the behavior of fires that consume melted fats. Natural explanations, as well as unverified natural phenomena, have been proposed to explain reports of SHC. Current scientific consensus is that most, and perhaps all, cases of SHC involve overlooked external sources of ignition.
"Spontaneous human combustion" refers to the death from a fire originating without an apparent external source of ignition; the fire is believed to start within the body of the victim. This idea and the term 'spontaneous human combustion' were first both proposed in 1746 by Paul Rolli in an article published in the Philosophical Transactions. Writing in the British Medical Journal in 1938, coroner Gavin Thurston describes the phenomenon as having "attracted the attention not only of the medical profession but of the laity" as early as 1834 (more than one hundred years prior to Thurston's article). In his 1995 book Ablaze!, Larry E. Arnold wrote that there had been about 200 cited reports of spontaneous human combustion worldwide over a period of around 300 years.
The topic received coverage in the British Medical Journal in 1938. An article by L. A. Parry cited an 1823-published book Medical Jurisprudence, which stated that commonalities among recorded cases of spontaneous human combustion included the following characteristics:
"[...]the recorded cases have these things in common:
- the victims are chronic alcoholics;
- they are usually elderly females;
- the body has not burned spontaneously, but some lighted substance has come into contact with it;
- the hands and feet usually fall off;
- the fire has caused very little damage to combustible things in contact with the body;
- the combustion of the body has left a residue of greasy and fetid ashes, very offensive in odour."
Alcoholism is a common theme in early SHC literary references, in part because some Victorian era physicians and writers believed spontaneous human combustion was the result of alcoholism.
An extensive two-year research project, involving thirty historical cases of alleged SHC, was conducted in 1984 by science investigator Joe Nickell and forensic analyst John F. Fischer. Their lengthy, two-part report was published in the journal of the International Association of Arson Investigators, as well as part of a book. Nickell has written frequently on the subject, appeared on television documentaries, conducted additional research, and lectured at the New York State Academy of Fire Science at Montour Falls, New York, as a guest instructor.
Nickell and Fischer's investigation, which looked at cases in the 18th, 19th and 20th centuries, showed that the burned bodies were near plausible sources for the ignition: candles, lamps, fireplaces, and so on. Such sources were often omitted from published accounts of these incidents, presumably to deepen the aura of mystery surrounding an apparently "spontaneous" death. The investigations also found that there was a correlation between alleged SHC deaths and the victim's intoxication (or other forms of incapacitation) which could conceivably have caused them to be careless and unable to respond properly to an accident. Where the destruction of the body was not particularly extensive, a primary source of combustible fuel could plausibly have been the victim's clothing or a covering such as a blanket or comforter.
However, where the destruction was extensive, additional fuel sources were involved, such as chair stuffing, floor coverings, the flooring itself, and the like. The investigators described how such materials helped retain melted fat to burn and destroy more of the body, yielding still more liquified fat, in a cyclic process known as the "wick effect" or the "candle effect".
According to Nickell and Fischer's investigation, nearby objects often went undamaged because fire tends to burn upward, and it burns laterally with some difficulty. The fires in question are relatively small, achieving considerable destruction by the wick effect, and relatively nearby objects may not be close enough to catch fire themselves (much as one can get rather close to a modest campfire without burning). As with other mysteries, Nickell and Fischer cautioned against "single, simplistic explanation for all unusual burning deaths" but rather urged investigating "on an individual basis".
Steve Novella has said that skepticism about human spontaneous combustion is now bleeding over into becoming popular skepticism about spontaneous combustion.
A 2002 study by Angi M. Christensen of the University of Tennessee cremated both healthy and osteoporotic samples of human bone and compared the resulting color changes and fragmentation. The study found that osteoporotic bone samples "consistently displayed more discoloration and a greater degree of fragmentation than healthy ones." The same study found that when human tissue is burned, the resulting flame produces a small amount of heat, indicating that fire is unlikely to spread from burning tissue.
Some hypotheses attempt to explain how SHC might occur without an external flame source, while other hypotheses suggest incidents that might appear as spontaneous combustion actually had an external source of ignition – and that the likelihood of spontaneous human combustion without an external ignition source is quite low. Benjamin Radford, science writer and deputy editor of the science magazine Skeptical Inquirer, casts doubt on the plausibility of spontaneous human combustion, "If SHC is a real phenomenon (and not the result of an elderly or infirm person being too close to a flame source), why doesn't it happen more often? There are 5 billion [The world's population reached 5 billion in 1987] people in the world, and yet we don't see reports of people bursting into flame while walking down the street, attending football games, or sipping a coffee at a local Starbucks." Paranormal researcher Brian Dunning states that SHC stories "are simply the rare cases where a natural death in isolation has been followed by a slow combustion from some nearby source of ignition." He further suggested that reports of people suddenly aflame should be called "Unsolved deaths by fire", stating that an unknown cause did not necessarily imply that the fire lacked an external ignition source.Almost all cases of SHC involve persons with low mobility due to advanced age or obesity, along with poor health. Victims show a high likelihood of having died in their sleep, or of being unable to move once they had caught fire.
Cigarettes are often seen as the source of fire, as the improper disposal of smoking materials causes one of every four fire deaths in the United States. Natural causes such as heart attacks may lead to the victim dying, subsequently dropping the cigarette, which after a period of smouldering can ignite the victim's clothes.
The "wick effect" hypothesis suggests that a small external flame source, such as a burning cigarette, chars the clothing of the victim at a location, splitting the skin and releasing subcutaneous fat, which is in turn absorbed into the burned clothing, acting as a wick. This combustion can continue for as long as the fuel is available. This hypothesis has been successfully tested with animal tissue (pig) and is consistent with evidence recovered from cases of human combustion. The human body typically has enough stored energy in fat and other chemical stores to fully combust the body; even lean people have several pounds of fat in their tissues. This fat, once heated by the burning clothing, wicks into the clothing much as candle wax (which typically was originally made of animal fat) wicks into a lit candle wick to provide the fuel needed to keep the wick burning. The protein in the body also burns, but provides less energy than fat, with the water in the body being the main impediment to combustion. However, slow combustion, lasting hours, gives the water time to evaporate slowly. In an enclosed area, such as a house, this moisture will recondense nearby, such as on windows. Note that feet often have the least fat, so don't typically burn. (Hands also have little fat, but may burn if on the abdomen, which provides all the needed fat.)
John Abrahamson suggested that ball lightning could account for spontaneous human combustion. "This is circumstantial only, but the charring of human limbs seen in a number of ball lightning cases are very suggestive that this mechanism may also have occurred where people have had limbs combusted," says Abrahamson.
Scalding can cause burn-like injuries, including death, without setting fire to clothing. Although not applicable in cases where the body is charred and burnt, this has been suggested as a cause in at least one claimed SHC-like event.
Brian J. Ford has suggested that ketosis, possibly caused by alcoholism or low-carb dieting, produces acetone, which is highly flammable and could therefore lead to apparently spontaneous combustion.
SHC can be confused with self-immolation as a form of suicide. In the West, self-immolation accounts for 1% of suicides, while Radford claims in developing countries the figure can be as high as 40%.
Sometimes there are reasonable explanations for the deaths, but proponents ignore official autopsies and contradictory evidence, in favor of anecdotal accounts and personal testimonies.
Larry E. Arnold in his 1995 book Ablaze! proposed a pseudoscientific new subatomic particle, which he called "pyrotron". Arnold also wrote that the flammability of a human body could be increased by certain circumstances, like increased alcohol in the blood. He also wrote that extreme stress could be the trigger that starts many combustions. This process may use no external oxygen to spread throughout the body, since it may not be an "oxidation-reduction" reaction; however, no reaction mechanism has been proposed. Researcher Joe Nickell has criticized Arnold's hypotheses as based on selective evidence and argument from ignorance.
In his 1976 book Fire From Heaven, UK writer Michael Harrison suggests that SHC is connected to poltergeist activity because, he argues "the force which activates the 'poltergeist' originates in, and is supplied by, a human being". Within the concluding summary, Harrison writes: "SHC, fatal or non-fatal, belongs to the extensive range of poltergeist phenomena."
On July 2, 1951, Mary Reeser, a 67-year-old woman, was found burned to death in her house after her landlady realized that the house's doorknob was extremely hot. The landlady notified the police, and upon entering the home, they found Reeser's remains completely burned into ash, with only her lower legs remaining. The chair she was sitting in was also destroyed. During the investigation, detectives found that Reeser's temperature was around 3500 degrees Fahrenheit, which puzzled the investigators due to such hot temperatures leaving almost all the room Reeser was in intact. Reeser was a user of sleeping pills, as well as a smoker. A common theory was that she was smoking a cigarette after taking sleeping pills, and then fell asleep while still having a lit cigarette, which would have burned her gown, leading to her death. Investigators also found that the fire had burned a socket, which stopped a clock at 2:26am, which states that Reeser had been burned at around that time.
Henry Thomas, a 73-year-old man, was found burned to death in the living room of his council house on the Rassau estate in Ebbw Vale, South Wales, in 1980. His entire body was incinerated, leaving only his skull and a portion of each leg below the knee. The feet and legs were still clothed in socks and trousers. Half of the chair in which he had been sitting was also destroyed. Police forensic officers decided that the incineration of Thomas was due to the wick effect. His death was ruled 'death by burning', as he had plainly inhaled the contents of his own combustion.
In December 2010, the death of Michael Faherty in County Galway, Ireland, was recorded as "spontaneous combustion" by the coroner. The doctor, Ciaran McLoughlin, made this statement at the inquiry into the death: "This fire was thoroughly investigated and I'm left with the conclusion that this fits into the category of spontaneous human combustion, for which there is no adequate explanation."