What Causes Spontaneous Human Combustion?

Things don’t just burst into flames! Except occasionally they do. This is phenomena known as spontaneous combustion. It can happen in piles of damp straw when microbes, formed from the decaying matter, heat the bales to a temperature where they can catch fire. Over the course of history, there have been cases that suggest that this could happen to humans too. But could it? Let’s investigate.

spontaneous human combustion

There are reported instances of spontaneous human combustion (or SHC) throughout modern history. Back in the 1850’s Dickens even used it as a device for killing off one of his characters. The reported incidents of the phenomena all bare a lot in common. The victim is burned to a pile of ash. There is very little damage to the surrounding area and extremities will often remain intact. There is also quite often a greasy residue covering walls at the scenes. It is also notable that nearly every victim of SHC has been a smoker.

How can stuff just burst into flames

Everything has a temperature whereby if conditions are correct it can ignite without an external spark or flame. In human beings that temperature is fairly high. Conditions need to be correct in order for this to happen.

The methane theory

One theory on how SHC happens is related to the body’s production of methane gas. The theory states that the methane produced in the gut builds up, possibly due to obstruction and then enzymes in the body react to this causing people to burn from the inside out. This is a tidy explanation in so much as because the burning starts within it explains to some extent why there is no damage to the surrounding area.

However, the fly in the ointment is that we are not the only animal that produces methane. In fact, cows produce a great deal more of the gas than humans do and to our knowledge (yes, we did have a look) there are no reported cases of spontaneous cow combustion!

The wick theory

The wick theory is a popular theory that may explain the phenomena. Picture, if you will, a wax candle, the flame upon the wick heats the wax which soaks into the wick and acts as a fuel source to keep it burning. This is usually pretty-well contained.

The theory is that with the wick effect that human fat cells act in the place of the wax. The melting fat soaks into their clothes or blankets and keeps them slowly burning. Reducing them to a pile of ash without doing too much damage to the surrounding area. This also could explain what the greasy residue is in these cases. It’s just human fat.

Experiment on pig

In the late nineties, an experiment similar to this was carried out on a pig. It was rapped in a blanket doused in petrol and set alight. This did little damage to the surrounding area and the pig was reduced to little more than a pile of ash and a few remaining limbs. This seems to suggest this is the obvious explanation tor SHC, but there is a slight problem with this theory too. In none of the cases of SHC was petrol, or any other kind of accelerant found present.


Cases of supposed SHC are fascinating. Debate still rages on over whether it is actually a thing! Scientists haven’t proved conclusively that human being can just “burst into flames” but there are enough cases to show that something happens and perhaps one day we will discover what it is that led to the death of these people. Surely they can’t all have been elaborate hoaxes, could they?

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