‘Hic locus est ubi mors gaudet succurrerevitae’. The motto of morgues andanatomy theatres, translating as ‘This is the place where death delights toteach the living’. These words have appeared above mortuary doors in hospitalsand universities around the western world for over 300 years. Historically speaking,science has recognised the potential wealth of knowledge that lies in the studyof our dead, encouraging a death positive attitude. However, over the lastthree centuries, societal norms have challenged this attitude to mortality.Western cultures in general deem the scientific attention on human cadavers asinappropriate or indecent.
As a result, we have a culture of ignorancesurrounding mortality. The academic study of death and what happensafter is extremely underfunded, lacking in facilities and opportunities forresearch, and overall under recognised. (Bristow et al.
2010) There is a needfor a more focused and recognised specialism within the areas of anatomy andpathology. Forensic taphonomy (the forensic study of the post-mortemdecomposition process) and mortuary sciences are perfect examples ofdisciplines with massive limitations in our current society. They focus on thedead’s contribution to the living and respectfully study post-mortem fate ofhumanity. The human cadaver is usually first andforemost studied from the perspective of pathology. Specialists in this areaare comfortable with a ‘fresh’ cadaver, essentially within hours of deathitself.
Forensic pathologists, anatomical pathologists and other relateddisciplines examine the medical aspects of death but often ignore what happensto the cadaver in the weeks and months after death. From the oppositeperspective, forensic anthropologists and archaeologists work with mostly dry,skeletal, remains. They too often ignore the intermediary processes, whatexactly happens between a fresh cadaver and a skeleton? (Pinheiro, 2006) This grey area in between the twoextremes is the under recognised specialism in question. To understand what the study of decompositioncan teach us, we need to first understand the basic underlying biologicalprocesses that are involved.
It is human nature to find such informationunpleasant, but it is comforting to remember that the scientific study ofcadavers can be seen to restore dignity and purpose after death by contributingto the greater good. SOMATIC DEATH & THE FRESH CADAVERAt first the abstract concept and definitionof death might seem obvious; however, it is in fact a heavily debated issue.Death can be seen as a process, separated into two distinct phases. (Knight, 1996) The first, somaticdeath, is the irreversible cessation of all vital biological functions in aliving organism. It is the general consensus among the medical community thatdeath can be pronounced in this phase, as cardiac and respiratory arrest resultin anoxia causing eventual brain death.
It is followed by a second phase, moleculardeath, the destruction of individual cells and tissue. (James et al. 2011) Moleculardeath is essentially the decomposition of the cadaver.The human cadaver upon somatic death is inthe ‘fresh’ stage of decomposition, characterised by four distinct post-mortemphenomena. The first of these, pallor mortis, is the pale appearance of thecomplexion in the hours after somatic death, resulting from the lack of bloodcirculation in the capillaries. The second sign, algor mortis, is the steadydecline in body temperature, occurring in the first hours after death. Thetemperature continues to decline until the internal temperature is balancedwith the external environmental temperature. (Goff, 2010)After an initial period of primary muscleflaccidity after death, the muscles stiffen and may even contract, causing’cadaveric spasm’.
The third sign, rigor mortis causes the muscles and limbs tostiffen, as actin and myosin filaments bind irreversibly. Without theproduction of ATP in the body these filaments cannot detach and within approximately12 hours the whole body becomes rigid. (Knight, 1996) The stiffness beginsto subside in the next stage of decomposition as proteins are degraded andtissues begin to break down. Livor mortis, a purple pattern ofdiscolouration on the skin is of particular interest to forensic science. Thishappens as blood settles in the circulatory system under the influence of gravity,blood cells haemolyse and rupture, leaking pigments out of the blood vesselsand into surrounding tissues. The pale, almost white areas of the pattern,occur due to pressure pallor as a consequence of the position of the cadaver.
(James et al. 2011) For example, a body lying on its back will have distinct palepatches on the shoulder blades, the pelvic area, back of calves etc. Clothing and other objects can alsoimpact the pattern formation, e.g. underwear, jewellery, ligatures. From this,forensic scientists can deduce many theories in relation to the circumstancessurrounding the death.
Livor mortis can also indicate the movement of a body inthe first 12 hours after death. After this time the pattern of discolourationbecomes fixed and will not change if the body is moved. Before this fixationoccurs, if a body has been moved there may be more than one pattern of livormortis. This is a useful indicator for forensic investigation. As the fresh stage progresses the first oftwo taphonomic processes, autolysis, begins. This is an abiotic process of destructionby chemical and enzymatic mechanisms, causing the body to begin to digestitself. (Smith, 1955) Cells are deprivedof oxygen, CO2 levels in the blood increase, decreasing the body’s Ph. Thisleads to rapid cell death as lysosomal enzymes digest them from inside.
Thiscauses cells to burst and release nutrient rich fluid which feeds microbes inthe second taphonomic process, putrefaction. PUTREFACTION & THE STAGES OF DECAY Putrefactionis responsible for the gradual dissolution of the entire cadaver as thephysical body is reduced to liquids, gases and salts. Unlike autolysis,putrefaction is a biotic process which occurs with the help of microbes anddetritivores (organisms that feed on dead organic matter). This occurs in aseries of stages, beginning with the ‘bloat’ stage, followed by a period ofactive decay and finally advanced decay. In aliving human there is an estimated 100 trillion bacteria inside the body. Thereis a harmonious relationship between them during life. Once the body dies, thebacteria play a different role.
They digest cells and tissues from inside thebody. As they breakdown the cells, they produce a series of gases, which beginto accumulate in the internal cavities. This causes the body to drasticallyincrease in volume as the gases build up.
It begins to accumulate in thestomach and intestines, so there is a prominent abdominal distension present.Severe bloating can cause oedema of the head, neck and face, where the eyes andtongue often protrude outwards. The pressure build-up can cause fluid purgefrom all orifices, including a distinct tracheobronchial foam coming from thenose and mouth. The putrefactive process is marked by a green discolouration,cause by the breakdown of haemoglobin in the blood cells into sulphaemoglobin.
(Haglund & Sorg, 1997) Theprogressing destruction of the bloat stage leads to the first of two decaystages, active decay. Necrophagous insects are attracted by the odour of thedecomposing cadaver and begin to colonise it. Larval infestation causes rapidtissue loss as maggots eat the flesh at remarkable speed. Putrefactive blistersform on the superficial layers of the skin, as gases force fluids out of thetissues. The loss of cohesion in the soft tissue leads to the evacuation of thegas build up during the bloat stage. This causes all the distension tocollapse.
The epidermis becomes extremely delicate and can come off in largesheets, known as skin slippage. Forensic scientists have developed a techniqueto wear ‘gloves’ of skin slippage on their own hands for fingerprinting,helping with identification. (James et al.
2011) Advanceddecay proceeds as soft tissues disintegrate, the internal organs begin toliquefy and dissolve completely. Some organs are more resistance due to theprotein content in their molecular structure. (Gunn, 2006)For example, the uterus, the prostate gland and the heart are the last organsto submit to decomposition.
Tendons and ligaments are all that is left attachedto the skeleton at the end of the decay process. Predators such as beetles andcarrion birds are attracted and often eat off all remaining tissues, leavingjust a skeleton behind. CORPSE ODOUR & FORENSIC ENTOMOLOGYThe characteristic odour of the putrefactiveprocess is caused by foul smelling organic compounds resulting from thedecomposition of amino acids. The odour has been compared to that of thedecomposition of protein rich plants, e.g.
duckweed. Putrescine (1,4-diaminobutane) ,is produced by the decarboxylation of arginine. Cadaverine (1,5-pentanediamine),is produced by the decarboxylation of lysine. (Rosen, 2015)The study of the odour of death has beenof huge forensic importance. The training of specialised K9 officers to detectdecomposing bodies has been a landmark in forensic investigation. Consideringthat the average human has five million sensory cells in their nose and compareto the average dog, who has 200 million sensory cells in their nose, theenhanced sense of smell in a dog can have many practical uses.
Their sense ofsmell is further enhanced by the presence of Jacobson’s organ, a specialolfactory sense organ in the roof of the mouth that detects large moleculesubstances that often have no detectable odour. (Stejskal, 2013) K9 dogs have been trained to detect thescent of drugs, explosives and chemical accelerants (in suspected arson cases).They have been trained as search and rescue dogs, to help find missing persons,and to track scents, to help trace the movements of fugitives. Cadaver dogshave been trained to detect different odours related to different stages ofdecomposition.
They are trained as either air scenting dogs, to pick up a scentin open air and find its source, or trailing dogs, to follow a scent on theground. Using traditional Pavlovian conditioning, these dogs are trained toperform a specific signalling action to alert their handler when they locate ascent. K9 cadaver dogs have been able to detect decomposing bodies buriedunderground and even submerged in water. (Rebmann et al.
2000)The odour of these putrefactive compoundsattracts detritivores to the cadaver. Forensic entomologists have studied andidentified a range of common necrophagous species that can help in forensicinvestigations. Blow flies (Calliphoridae) and flesh flies (Sarcophagidae) aretwo of the first detritivores to colonise the decaying cadaver. House flies(Muscidae) come to the body during the bloat stage, and cheese flies(Piophildae) are attracted during advanced decay. Extensive research has beenconducted to examine the life cycles of these insects and their behaviour whencolonising a cadaver. (Knight, 1996) The blow fly forexample, oviposits it’s eggs around the orifices or any open wounds. The eggshatch to reveal larvae (maggots) who eat the surrounding flesh at an alarmingspeed. An area of maggot activity focused away from the usual orifices of acadaver indicates the presence of open wounds, which can aid in determining thecause of death.
After three larval stages, the larvae enter the pupa stage(cocoon like stage) before they emerge as adult flies. This life cycle occursin a specific time range, which is hugely important when determining thepost-mortem interval (time since death). Time of death can be calculated to withina margin of error of just 24 hours. Entomology can also be useful intoxicological investigation, by the analysis of flesh eating insects, and humanDNA can be extracted from blood sucking insects to help identify suspects. ENVIRONMENT & THE BODY FARM The dryskeletal remains signal the end of the decomposition process if it occurs inideal conditions. If certain extreme conditions are present, it may haltaspects of decomposition so greatly that the cadaver is in a state of naturalpreservation.
As with all biological processes, there is a long list ofvariable factors that affect decomposition. Primarily studied, environmentalfactors, such as temperature, exposure to oxygen or sunlight, burial, soiltype, rainfall, humidity or submersion in water. The possible number of othervariables is almost impossible to predict but some stand out for forensicsignificance. The cause of death can hugely impact decomposition, as can any artificialembalming procedures. The physical body weight is crucial as more obesecadavers decay much quicker than thinner ones, due to the quantity of adiposetissue. (Di Maio & Di Maio, 2001) Over the last40 years, forensic science has benefited from a range of discoveries intaphonomy research.
Many of these discoveries are thanks to specialisedresearch facilities known as body farms. There are seven such academic sites inthe US and proposals in process in Australia, Netherlands and UK. Before theadvent of human body farms, pig carcasses were studied due to theirphysiological similarities to humans.
Dr. Bill Bass founded the AnthropologicalResearch Facility at the University of Tennessee in the late 1970’s, despitemuch opposition from protestors and the public in Knoxville. Body farms focuson the importance of the environment in the understanding of taphonomy on aforensic level. Donated cadavers are placed in a variety of environments, forexample in the boot of a car or submerged in a river.
They are allowed todecompose naturally while scientists from a range of forensic disciplines studythem. This has been a huge step in progress in this discipline, but scientistsadmit there is still a lot we don’t know. (Vass, 2001) Dr. AnnaWilliams of Huddersfield University and Prof.
John Cassella of StaffordshireUniversity are among the many academics putting pressure on the UK government.It is currently illegal in the UK to use human tissue for forensic science. (Keating, 2017) Access to donatedbodies is exclusively for the medical profession. Dr. Williams is innegotiation with the Human Tissue Authority to include taphonomy research intheir ‘scheduled purposes’. This would make it possible to get a HTA license toopen a ‘body farm’ facility for human taphonomic research in the UK. (Williams,2015a) The importance of this research cannot be ignored.
Society’s attitudesand religious beliefs cannot block progress in such an essential area. (Vass, 2001)