How Spontaneous Human Combustion Works

Terrifying, isn't it? To imagine that you could be sitting in your favourite easy chair, happily reading UNIX in a Nutshell, and then your body just COMBUSTS -- spontaneously -- and you're a pile of ashes. A coroner in Ireland recently ruled that's exactly what happened to Michael Faherty, 76, who burned to death last December while minding his own business and collecting his pension.

Except for the floor below and the ceiling above the body, the apartment and furnishings surrounding Faherty's body were left intact. The coroner couldn't find any other explanation besides spontaneous human combustion. If something external had caused the fire, wouldn't the rest of the house have gone up in flames as well?

It's frightening at first blush. But don't get too upset. Spontaneous human combustion is probably not real. Yes, approximately 200 reports of such have occurred in the past 300 years. But in 1998, scientists in UK came up with a more plausible explanation: the "wick effect".

Come to think of it, the idea that your body could emulate a candle wick is not really comforting, either. It still reduces your humanness to pile of charcoal in short order. And just to make it a little more gruesome, your arms and legs might be left intact. But at least there is some logic behind the wick effect.

On the BBC Television program Q.E.D. (quod erat demonstrandum, which means "that which was to be demonstrated"), Dr John DeHaan demonstrated the wick effect with a dead pig. They wrapped the poor thing in a blanket, then used a small drop of gasoline and a spark. It took a while for the flame to catch, but eventually it did, and flames began burning intensely hot but with low flames. The pig burned completely -- even its bones were incinerated. But the surroundings were mostly spared -- only a nearby television, the floor below and the ceiling above the pig were affected by the fire. It's exactly what the result of most reported cases of spontaneous human combustion looks like.

The theory behind the wick effect is that the spark (for a human, it might be a burning cigarette or a spark from a fireplace) burns through clothing, then splits the skin enough to access subcutaneous fat. Most victims are alone and presumed to have fallen asleep so they don't immediately notice the spark. The fat is then absorbed into the clothing and behaves like a candle wick, fuelling the flames until no fat is left.

You might think that a pig has a lot more fat than a human. We actually have a similar fat content to our porcine friends. So it makes sense that limbs would sometimes remain intact, since they contain less fat.

As for the recent case in Ireland, perhaps the coroner hand't heard of the wick effect. But to this layperson's eye, Mr Faherty seems like a prime candidate. He was found next to an open fireplace, which gives a potential source for a spark.

One other interesting note: Faherty was diabetic. According to this "Material Safety Data Sheet" from ScienceLab, a firm that supplies chemical and laboratory equipment, insulin may be combustible at high temperature. Just sayin'.

WATCH MORE: Science & Health News


    Great article Kristen! Nice to see some critical thinking and inquiry applied to this headline.

    Wick effect.. maybe.. makes sense.. but just how fast does someone "combust" when experiencing the wick effect? Surely it wouldn't be instaneous..? And if not, then surely the person would be thrashing around from the pain or at least attempting to put the fire out?

    I'm certainly a skeptic, to be sure, but I'm also skeptical about the wick effect as a cause.

      Its entirely possible that someone would drink way too much and just pass out till it was too late, or abuse sleeping pills or even just die of natural causes then catch fire. Plenty of possible causes.

      The wick effect isn't the cause of ignition, that would be something else. In this case, most likely a spark from the open fireplace.

      The wick effect explains the details of the fire - body/bones reduced to ash, minimal damage to anything else.

      As for thrashing around that assumes that the victim was both conscious and physically able to. If he was unconscious, already dead, etc... there would be no thrashing. If the fire was so intense as to instantly kill someone and prevent any thrashing more than just the body would be reduced to ash...

      In the end, what's more probable:

      1. an unsolved death followed by a slow combustion via the wick effect started by a nearby source of external ignition


      2. a death caused by bursting into flames with no external source of ignition

      The wick effect has been demonstrated to take many hours to consume the body as the flames are low intensity unlike cremation that takes a small amount of time at high temperatures. The most puzzling aspect is the lack of bones as even after cremation there are usually some bones intact. Interestingly, the test have been able to reproduce destruction of bones at these much lower temperatures over a long duration.

      Most victims are elderly and a high percentage smokers. The combustion is not necessarilly the cause of death just the cause for the incinerated body. It is more likely the person had suffered a heart attack or stroke or was similarly incapacitated even possibly already unconscious from the smoke from clothing, blankets, or furniture. As with a candle in a closed room, there not not excessive volumes of visible smoke or even high flames to create an visible cause for concern by those outside. Theres an interesting documentary where this is reproduced that is worth watching (can't remember the title - sorry).

    Not sure it was mentioned but aren't most suspected victims of spontaneous combustion a little husky? super sized? Big fatty mcfat fattys?

    It certainly adds credence to the Wick theory.

    One think I don't get is that none of the victims of SC seem to have appeared distressed when they died, surely any kind of fire, even with a wick affect your conscious would alert you, and your arms would flail, or legs kick or you would get out of your chair in a screaming fireball, lighting up curtains and other stuff just by contact. You might have already combusted and died, but you won't go quitely.

      Exactly, and that would be the same if you spontaneously burst into flames from some unknown and unexplained cause from inside you.

      Much more likely that the person died from an entirely natural cause, followed shortly there after by a slow-burning fire (ie, the wick effect) started from an external ignition source (eg, a spark from the open fire place).

      To me all these cases seem more likely to be an unsolved death followed by a slow combustion.

    Fascinating piece but could you have put a 'possible distressing images' disclaimer first Giz? There are people I need to be careful reading this around.

    On topic, yeah the wick effect seems to be the most commonly accepted cause. But the question remains, if it can happen that easily, why doesn't it happen more? Plenty of people accidentally set themselves on fire and *don't* spontaneously combust. They burn the house down and die, sure, but that's rather different.

    NSFW warning would be nice.

      If pictures of a young Drew Barrymore cause you to do something embarrassing at work then that's not Giz's fault shirley?

    There might be a certain kind of spark that has to generate, like some 1 in a million spark that that occurs due to some chemical imbalance/reaction/lack of or extra atoms/electrons/protons etc, causing it to burn in a certain way and longer.

      Don't try to rationalise it. It's pretty much confirmed that SHC is a crock of shit, just like fan death. In 2011 when just about everyone is connected with camera phones, CCTV and so on, it's extraordinarily convenient that this no longer happens and could be proven real.

    Why then, like UFO's, does this only seem to happen when there is nobody else around to see it or try to stop it? "Yes officer, I came inside and my husband was alight. So I had a cuppa and some cake, called my Mum and chatted for a while, then rang the Police immediately!" Strange nobody else saw anything is all.

    What rot. I'm halfway through reading Ablaze - which is a veritable compendium of all documented SHC cases over the last several hundred years. Many, many (not all) of the cases have the following points in common - which blow your article and its hypthoesis apart:
    * In many (not all) of the cases there was absolutely no source of spark, flame, fire - anything that would ignite nearby. Nothing. So the 'spark' theory can't be considered conclusive here. The 'wick effect' you speak of requires a source of ignition. A large number of SHC have police evidence/firemen's evidence/doctor's evidence/eyewitness evidence that no source of spark/flame was to be found anywhere within the vicintiy of the SHC scene. So if you wrapped your pig in the gasolene soaked blanket (mind, none of the SHC cases documented detail people who have wrapped themselves in gasolene soaked garments!) and then stood back, ensuring no source of ignition was around, can we expect to see the 'wick effect' succeed? No. But it is in these exact circumstances, time and time again, that its been documented and evidenced that SHC does take place.
    * many of the cases reported in this book (from police & medical documents etc) show that although the person's body burned up almost entirely, their clothes remained completely intact without burn holes in them - but were synged on the inside. Ie the heat source was coming from the body outwards. No burn hole indicates no external heat source was applied from the outside of the clothes that then ignited the inside of the body as you suggest above.
    * Most victims are NOT alone. THere are many documented cases of people catching on fire spontaneously, having their hair catch alight spontaneously, shooting flames from their fingers spontaneously that have been eyewitnessed.
    * Nor are those victims necessarily asleep. So the documents referred to in Ablaze show.
    * Finally SHC is not slow. It is FAST. In fact the photo you show (top one of) "heavy and careless smoker" (so perhaps not an authentic case of SHC in that there was a possible source of ignition - her cigarettes), Helen Carter - burned up in 21 minutes - including time for photographs. Your call above "it took a while for the flame to catch above" is a little misleading. The fire dept investigating Helen Carter's case said that smouldering takes 2-3 hours normally before it ignites into flame. So... no the wick effect again, cannot be considered the secret solution behind SHC. This woman (and many other cases besides) combust very quickly, whereas as you almost admit: the wick effect takes a much longer time. 20 mins vs 3 hours.
    Okay, said my piece.
    I would advise anyone reading this article who is interested in knowing as much as we can know about the absurdity of SHC to read Ablaze by...Arnold Evans. So far, he doesn't (I'm only halfway) postulate any theories - just outlines the many unexplainable areas of SHC cases (many more than I"ve listed above) as they've been documented over the centuries by various experts and experiencers (no not everyone who experiences 'spontaneously catching on fire' actually dies!). Remarkable reading. Ablaze doesn't answer much (that's the point it makes - we can't at this point explain SHC!), but it certainly puts paid to the skeptics who try to answer by rationalising away the actual facts of the various cases. Let's just admit we haven't found a theory that covers off all bases of the many cases of SHC. The above one requiring an external source of ignition is... really missing the point. So many of the documented cases specifically baffle the experts on scene bc it is evidenced there is NO outside source of ignition.

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