Spontaneous human combustion (SHC) is a name used to describe cases of the burning of a living human body without an apparent external source of ignition. Some regard SHC as a unique and currently unexplained phenomenon, others feel that cases described as SHC can be understood using current generally-accepted scientific principles, but the most common view by far is extreme skepticism. While there have been about 200 cited cases worldwide over a period of around 300 years, most of the alleged cases are characterised by the lack of a thorough investigation, or rely heavily on hearsay and oral testimony. In many of the more recent cases, where photographic evidence is available, it is alleged that there was an external source of heat present (often cigarettes), and nothing occurred "spontaneously."

Causes

There are many hypothesised explanations which account for the various cases of spontaneous human combustion. These generally fall into one of three groups: paranormal explanations (e.g. a ghost or alien caused it), natural explanations that credit some unknown and otherwise unobserved phenomenon (e.g. the production of abnormally concentrated gas or raised levels of blood alcohol cause spontaneous ignition), and natural explanations that involve an external source of ignition (e.g. the victim dropped a cigarette).

Objections to natural explanations usually revolve around the degree of burning of the body with respect to its surroundings. Indeed, one of the common markers of a case of SHC is that the body — or part of it — has suffered an extraordinarily large degree of burning, with surroundings or lower limbs comparatively undamaged.