|S cience Fact or Science Fiction|
Spontaneous human combustion (SHC) is the alleged process of a human body catching fire as a result of heat generated by internal chemical action. While no one has ever witnessed SHC, several deaths involving fire have been attributed to SHC by investigators and storytellers.
In the literature, spontaneous human combustion is almost exclusively reserved for corpses. One 17th century tale, however, claims that a German man self-ignited due to his having drunk an excessive amount of brandy. If drinking a great quantity of brandy caused self-combustion, there should be many more cases to study than this isolated report from Germany.
Many of the SHC stories have originated with police investigators who have been perplexed by partially ignited corpses near unburnt rugs or furniture. "What else could it be?" they ask. Many of the allegedly spontaneously combusted corpses are of elderly people who may have been murdered or who may ignited themselves accidentally. Yet, self-ignition due to dropping a lit cigarette, or ignition due to another person are ruled out by the investigators as unlikely. Instead, they favor an explanation which requires belief in an event which has never been witnessed in all of human history--unverifiable or reliable testimonies to the contrary.
Physical Possibility of SHC
The physical possibilities of spontaneous human combustion are remote. Not only is the body mostly water, but aside from fat tissue and methane gas, there isn't much that burns readily in a human body. To cremate a human body requires enormous amounts of heat over a long period of time. To get a chemical reaction in a human body which would lead to ignition would require some doing. If the deceased had recently eaten an enormous amount of hay that was infested with bacteria, enough heat might be generated to ignite the hay, but not much besides the gut and intestines would probably burn. Or, if the deceased had been eating the newspaper and drunk some oil, and was left to rot for a couple of weeks in a well-heated room, his gut might ignite.
It is true that the ignition point of human fat is low, but to get the fire going would probably require an external source. Once ignited, however, some researchers think that a "wick effect" from the body's fat would burn hot enough in certain places to destroy even bones. To prove that a human being might burn like a candle, Dr. John de Haan of the California Criminalistic Institute wrapped a dead pig in a blanket, poured a small amount of gasoline on the blanket, and ignited it. Even the bones were destroyed after five hours of continuous burning. The fat content of a pig is very similar to the fat content of a human being. The damage to the pig, according to Dr. De Haan "is exactly the same as that from supposed spontaneous human combustion."
In their investigation of a number of SHC cases, Dr. Joe Nickell and Dr. John Fisher found that when the destruction of the body was minimal, the only significant fuel source was the individual's clothes, but where the destruction was considerable, additional fuel sources increased the combustion. Materials under the body help retain melted fat that flows from the body and serves to keep it burning.*
They also found that plausible external sources of ignition, such as candles, lamps, cigarettes, fireplaces, etc., were rejected by investigators in favor of the implausible internal spontaneous combustion.