Decomposition is a natural process that begins shortly after death in all living organisms. This complex biological event involves the breakdown of organic matter by microorganisms and is inevitably accompanied by a distinct and often unpleasant odor. This odor signals the progression of decay, indicating biological changes are underway within the deceased.
The Distinct Odor of Decomposition
The smell associated with a decaying body is often referred to scientifically as a “decompositional odor” or the “smell of death.” While not a single named compound, the term “putrefaction” describes the process that creates this unique scent. This odor is typically described as intensely putrid, sickeningly sweet, or reminiscent of rotting flesh. It is generally recognized as distinct and identifiable.
This distinctive scent is not only potent but also highly pervasive, often lingering in an environment long after the source has been removed. The intensity and specific characteristics of the smell can evolve as the decomposition process progresses through different stages. Initially, it might be nauseatingly strong, sometimes developing sour or sweet notes over time.
The Chemical Composition of the Smell
The characteristic odor of decomposition results from the release of various volatile organic compounds (VOCs) as bacteria break down tissues. Among the most significant contributors are putrescine (1,4-diaminobutane) and cadaverine (1,5-diaminopentane). These compounds are diamines produced from the bacterial breakdown of amino acids and proteins, imparting a strong “rotting flesh” or “putrid” aroma. They have low odor thresholds, meaning only small amounts are needed for them to be detected.
Other compounds contribute to the complex scent profile. Sulfur-containing compounds like hydrogen sulfide (rotten eggs) and mercaptans, such as methanethiol (rotting cabbage), add to the foulness. Dimethyl disulfide and dimethyl trisulfide also contribute garlic-like or foul odors. Indole and skatole, found in feces, contribute musty or fecal notes, while anaerobic decomposition can produce aldehydes, ketones, and esters, adding a sickly-sweet undertone.
Factors Influencing the Decomposition Odor
Several factors influence the intensity, specific chemical profile, and rate at which the decomposition odor develops. Temperature is a significant variable, as warmer conditions generally accelerate microbial activity and thus speed up the decay process and odor production. Humidity also plays a role, impacting microbial growth and the release of volatile compounds.
The availability of oxygen influences the type of bacterial activity, with anaerobic breakdown producing different compounds, such as those responsible for sickly-sweet undertones. The presence of insects, particularly flies and their larvae, can significantly hasten tissue degradation, thereby intensifying the odor. Factors like the deceased’s health, presence of certain chemicals, or the environment can subtly alter the overall smell.