A Scientific Explanation for Spontaneous Human Combustion

FlamesThe phenomenon dubbed “spontaneous human combustion” (SHC) has been described in the medical and scientific literature for centuries, dating back to the late 17th century. SHC also has appeared in fictional literature by authors such as Charles Dickens and Herman Melville. There has been no conclusive scientific proof to explain how SHC happens—how human bodies, which are about 75% water, can ignite (supposedly spontaneously, hence the name) and burn at temperatures high enough to destroy bones, muscles and other soft tissues while leaving material in the immediate vicinity relatively untouched by the fire. Cases of SHC are rare, making it difficult to determine a cause. In a 2002 Journal of Forensic Science paper (1), the author estimated that there were only approximately 200 cases worldwide since the 17th century.

Recently, a case that has all of the hallmarks of SHC was reported in the Journal of Forensic Science (2), causing the authors to revisit the topic, list the commonalities of apparent SHC cases and re-iterate the current hypothesis that might explain this bizarre phenomenon.

This most recent example of SHC occurred in a small village in central France. The victim was a 57-year-old divorced man with alcohol and tobacco addictions, a violent temper and few social interactions. When no one had seen the man for 48 hours, the village mayor became concerned and notified police, who visited the man’s house. They found the man lying on the floor near a wood-burning stove; his body was almost completely carbonized from the distal third of his legs to the first lumbar vertebra. His lower legs, upper body, head, forearms and hands were relatively intact, as were a pile of newspaper, a straw chair and other combustible materials near the body.

The police investigation uncovered no signs of burglary, and all doors and windows were locked from the inside. An arson expert found no suspicious fuel sources or accelerants or other signs of foul play. The medical examiner performed an autopsy and concluded that the victim was dead before the fire had started. However, the cause of death could not be determined conclusively. Based on the significant signs of heart and coronary disease observed at autopsy and the victim’s medical history of coronary heart disease, hypertension and chronic heart failure, the most probable cause of death was heart failure complicated by excessive and chronic alcohol consumption.

Upon inspection, many of the details of this case match the typical features of SHC cases:

  1. The surroundings near the body are undamaged by the fire, even though some of the material is quite combustible. There are no obvious sources of fuel that would explain the fire.
  2. There is a heat or ignition source near the remains. This source can include a wood burning stove, a candle, cigar or cigarette, or even a water heater. The heat source is not always obvious because it may have been consumed in the fire.
  3. The middle third of the body is almost completely consumed by the fire, but the extremities are relatively unscathed. The condition of the clothing mimics that of the body—clothing in the midsection is destroyed, while the remaining clothing is still intact. These burn patterns are opposite of those associated with typical fire injuries, where the feet, hands and head are more extensively damaged than the midsection.

    The damage is usually restricted to one person, although there are two reported cases where SHC has claimed multiple victims (2 and references therein). In 1779, a couple was found dead in their home exhibiting all of the characteristics of SHC, and more recently, a dog succumbed to carbon monoxide poisoning when his owner was consumed by SHC.

  4. Autopsy results and toxicology and histopathology reports indicate that the burning occurred postmortem. Autopsy results often show signs of a recent heart attack or stroke or alcohol-related incapacitation or coma.
  5. There are no signs of suspicious activity, such as assault or arson, that might explain the victim’s death. Police have no reason to suspect the case is a homicide.
  6. Typical victims are elderly, obese women in North America or Western European with a history of alcohol dependency. They are often socially underprivileged or isolated.

After studying this case, the authors conclude that the man appeared to be a victim of SHC, although they bristle at the use of the term “spontaneous human combustion”. They note that “spontaneous human combustion is a reality in forensic practice, but burning of the body is not spontaneous” and so prefer the term “isolated body combustion” or “isolated central body combustion”.

The remaining question is: How did the man go from apparent heart attack victim to victim of spontaneous combustion?

Historical accounts from the 1700s and 1800s are often tainted by a religious or mystic perspective and explain SHC as punishment by a divine entity for bad behavior or alcohol abuse. The current, more scientific explanation is known as the wick effect theory (3). This theory likens a human body and clothing to a candle and postulates that the clothing acts as a wick to burn human fat, which is a liquid at 37°C (body temperature). Fat is the most flammable component of the human body, although soft tissue, bone and bone marrow also will burn if dehydrated and exposed to a direct flame. These components are not distributed evenly throughout the body; the midsection often has the highest fat content. In chronic alcoholics, especially women, this uneven fat distribution is even more pronounced, with more fat accumulating around the abdomen, buttocks and thighs—those areas consumed by spontaneous combustion. Controlled experiments performed in the lab support the wick effect theory and show that, once ignited, body fat wrapped in layers of skin and light clothing can burn slowly with no visible flame (1). Other researchers who study such topics believe that the fire would be sustained as long as fuel is available but is unlikely to be hot enough to ignite other combustible material in the vicinity (4,5).

Spontaneous human combustion is not an appealing end, obviously, but it does not appear to be the horror that the name might imply. Living humans do not spontaneously burst into flames.

Once again, science provides a perfectly reasonable explanation for a seemingly bizarre set of events.

References

  1. Christensen, A.M. (2002) Experiments in the combustibility of the human body. J. Forensic Sci. 47, 466–70.
  2. Levi-Faict, T.W. and Quatrehomme, G. (2011). So-called spontaneous human combustion. J. Forensic Sci. 56, 1334–9. PMID: 21392004
  3. Gee, D.J. (1965) A case of spontaneous combustion. Med. Sci. Law 5, 37–8.
  4. DeHaan, J.D., Campbell, S.J. and Nurbakhsh, S. (1999) Combustion of animal fat and its implications for the consumption of human bodies in fires. Sci. Justice 39, 27–38.
  5. DeHaan, J.D. and Nurbakhsh, S. (2001) Sustained combustion of an animal carcass and its implications for the consumption of human bodies in fires. J. Forensic Sci. 46, 1076–81.
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Terri Sundquist

Terri has worked as a Scientific Communications Specialist at Promega Corporation for more than 13 years, and prior to that, spent more than 5 years solving problems and answering questions as a Promega Technical Services Scientist. She graduated with B.S. degrees in Chemistry and Biology at the University of Wisconsin—River Falls, then earned her M.S. in Molecular Biology from the Mayo Graduate School in Rochester Minnesota.

3 thoughts on “A Scientific Explanation for Spontaneous Human Combustion

  1. Terri, what an intriguing blog. Perhaps the acronym needs revising…changing SHC to SHCAD, that is Spontaneous Human Combustion After Death? While vaguely disappointed that I’ll never see a person *poof* into flames, glad to hear that SHC was not the cause of death–wouldn’t wish that on anyone!
    You’ve heard the phrase “Heaven on Earth”; perhaps there is “Hades on Earth” as well?

  2. I, too, was glad to learn that SHC was not the cause of death in most (but, unfortunately, not all) cases. I’m not taking any chances though; I now have one more reason to spend my lunch hours on the treadmill: reduce the layer of combustible material around my waist.

  3. I have often wondered what the concentrations of lithium were in these cases or if there could be some other catalyst concentrations in the tissues building up over many years that have gone unnoticed.
    A bucket of fat set alight does not burn from the inside out.

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