‘Hic the post-mortem decomposition process) and mortuary sciences are

 ‘Hic locus est ubi mors gaudet succurrere
vitae’. The motto of morgues and
anatomy theatres, translating as ‘This is the place where death delights to
teach the living’. These words have appeared above mortuary doors in hospitals
and universities around the western world for over 300 years. Historically speaking,
science has recognised the potential wealth of knowledge that lies in the study
of our dead, encouraging a death positive attitude. However, over the last
three centuries, societal norms have challenged this attitude to mortality.
Western cultures in general deem the scientific attention on human cadavers as
inappropriate or indecent. As a result, we have a culture of ignorance
surrounding mortality.

The academic study of death and what happens
after is extremely underfunded, lacking in facilities and opportunities for
research, and overall under recognised. (Bristow et al. 2010) There is a need
for a more focused and recognised specialism within the areas of anatomy and
pathology. Forensic taphonomy (the forensic study of the post-mortem
decomposition process) and mortuary sciences are perfect examples of
disciplines with massive limitations in our current society. They focus on the
dead’s contribution to the living and respectfully study post-mortem fate of
humanity.

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The human cadaver is usually first and
foremost studied from the perspective of pathology. Specialists in this area
are comfortable with a ‘fresh’ cadaver, essentially within hours of death
itself. Forensic pathologists, anatomical pathologists and other related
disciplines examine the medical aspects of death but often ignore what happens
to the cadaver in the weeks and months after death. From the opposite
perspective, forensic anthropologists and archaeologists work with mostly dry,
skeletal, remains. They too often ignore the intermediary processes, what
exactly happens between a fresh cadaver and a skeleton? (Pinheiro, 2006) This grey area in between the two
extremes is the under recognised specialism in question.

To understand what the study of decomposition
can teach us, we need to first understand the basic underlying biological
processes that are involved. It is human nature to find such information
unpleasant, but it is comforting to remember that the scientific study of
cadavers can be seen to restore dignity and purpose after death by contributing
to the greater good.

 

SOMATIC DEATH & THE FRESH CADAVER

At first the abstract concept and definition
of 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, somatic
death, is the irreversible cessation of all vital biological functions in a
living organism. It is the general consensus among the medical community that
death can be pronounced in this phase, as cardiac and respiratory arrest result
in anoxia causing eventual brain death. It is followed by a second phase, molecular
death, the destruction of individual cells and tissue. (James et al. 2011) Molecular
death is essentially the decomposition of the cadaver.

The human cadaver upon somatic death is in
the ‘fresh’ stage of decomposition, characterised by four distinct post-mortem
phenomena. The first of these, pallor mortis, is the pale appearance of the
complexion in the hours after somatic death, resulting from the lack of blood
circulation in the capillaries. The second sign, algor mortis, is the steady
decline in body temperature, occurring in the first hours after death. The
temperature continues to decline until the internal temperature is balanced
with the external environmental temperature. (Goff, 2010)

After an initial period of primary muscle
flaccidity after death, the muscles stiffen and may even contract, causing
‘cadaveric spasm’. The third sign, rigor mortis causes the muscles and limbs to
stiffen, as actin and myosin filaments bind irreversibly. Without the
production of ATP in the body these filaments cannot detach and within approximately
12 hours the whole body becomes rigid. (Knight, 1996) The stiffness begins
to subside in the next stage of decomposition as proteins are degraded and
tissues begin to break down.

Livor mortis, a purple pattern of
discolouration on the skin is of particular interest to forensic science. This
happens as blood settles in the circulatory system under the influence of gravity,
blood cells haemolyse and rupture, leaking pigments out of the blood vessels
and 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 pale
patches on the shoulder blades, the pelvic area, back of calves etc. Clothing and other objects can also
impact the pattern formation, e.g. underwear, jewellery, ligatures. From this,
forensic scientists can deduce many theories in relation to the circumstances
surrounding the death. Livor mortis can also indicate the movement of a body in
the first 12 hours after death. After this time the pattern of discolouration
becomes fixed and will not change if the body is moved. Before this fixation
occurs, if a body has been moved there may be more than one pattern of livor
mortis. This is a useful indicator for forensic investigation.

As the fresh stage progresses the first of
two taphonomic processes, autolysis, begins. This is an abiotic process of destruction
by chemical and enzymatic mechanisms, causing the body to begin to digest
itself. (Smith, 1955) Cells are deprived
of oxygen, CO2 levels in the blood increase, decreasing the body’s Ph. This
leads to rapid cell death as lysosomal enzymes digest them from inside. This
causes cells to burst and release nutrient rich fluid which feeds microbes in
the second taphonomic process, putrefaction.

 

PUTREFACTION & THE STAGES OF DECAY

            Putrefaction
is responsible for the gradual dissolution of the entire cadaver as the
physical body is reduced to liquids, gases and salts. Unlike autolysis,
putrefaction is a biotic process which occurs with the help of microbes and
detritivores (organisms that feed on dead organic matter). This occurs in a
series of stages, beginning with the ‘bloat’ stage, followed by a period of
active decay and finally advanced decay.

            In a
living human there is an estimated 100 trillion bacteria inside the body. There
is a harmonious relationship between them during life. Once the body dies, the
bacteria play a different role. They digest cells and tissues from inside the
body. As they breakdown the cells, they produce a series of gases, which begin
to accumulate in the internal cavities. This causes the body to drastically
increase in volume as the gases build up. It begins to accumulate in the
stomach and intestines, so there is a prominent abdominal distension present.
Severe bloating can cause oedema of the head, neck and face, where the eyes and
tongue often protrude outwards. The pressure build-up can cause fluid purge
from all orifices, including a distinct tracheobronchial foam coming from the
nose 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)

            The
progressing destruction of the bloat stage leads to the first of two decay
stages, active decay. Necrophagous insects are attracted by the odour of the
decomposing cadaver and begin to colonise it. Larval infestation causes rapid
tissue loss as maggots eat the flesh at remarkable speed. Putrefactive blisters
form on the superficial layers of the skin, as gases force fluids out of the
tissues. The loss of cohesion in the soft tissue leads to the evacuation of the
gas build up during the bloat stage. This causes all the distension to
collapse. The epidermis becomes extremely delicate and can come off in large
sheets, known as skin slippage. Forensic scientists have developed a technique
to wear ‘gloves’ of skin slippage on their own hands for fingerprinting,
helping with identification. (James et al. 2011)

            Advanced
decay proceeds as soft tissues disintegrate, the internal organs begin to
liquefy and dissolve completely. Some organs are more resistance due to the
protein content in their molecular structure. (Gunn, 2006)
For example, the uterus, the prostate gland and the heart are the last organs
to submit to decomposition. Tendons and ligaments are all that is left attached
to the skeleton at the end of the decay process. Predators such as beetles and
carrion birds are attracted and often eat off all remaining tissues, leaving
just a skeleton behind.

 

CORPSE ODOUR & FORENSIC ENTOMOLOGY

The characteristic odour of the putrefactive
process is caused by foul smelling organic compounds resulting from the
decomposition of amino acids. The odour has been compared to that of the
decomposition 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 been
of huge forensic importance. The training of specialised K9 officers to detect
decomposing bodies has been a landmark in forensic investigation. Considering
that the average human has five million sensory cells in their nose and compare
to the average dog, who has 200 million sensory cells in their nose, the
enhanced sense of smell in a dog can have many practical uses. Their sense of
smell is further enhanced by the presence of Jacobson’s organ, a special
olfactory sense organ in the roof of the mouth that detects large molecule
substances that often have no detectable odour. (Stejskal, 2013) K9 dogs have been trained to detect the
scent 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 dogs
have been trained to detect different odours related to different stages of
decomposition. They are trained as either air scenting dogs, to pick up a scent
in open air and find its source, or trailing dogs, to follow a scent on the
ground. Using traditional Pavlovian conditioning, these dogs are trained to
perform a specific signalling action to alert their handler when they locate a
scent. K9 cadaver dogs have been able to detect decomposing bodies buried
underground and even submerged in water. (Rebmann et al. 2000)

The odour of these putrefactive compounds
attracts detritivores to the cadaver. Forensic entomologists have studied and
identified a range of common necrophagous species that can help in forensic
investigations. Blow flies (Calliphoridae) and flesh flies (Sarcophagidae) are
two 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 been
conducted to examine the life cycles of these insects and their behaviour when
colonising a cadaver. (Knight, 1996) The blow fly for
example, oviposits it’s eggs around the orifices or any open wounds. The eggs
hatch to reveal larvae (maggots) who eat the surrounding flesh at an alarming
speed. An area of maggot activity focused away from the usual orifices of a
cadaver indicates the presence of open wounds, which can aid in determining the
cause of death. After three larval stages, the larvae enter the pupa stage
(cocoon like stage) before they emerge as adult flies. This life cycle occurs
in a specific time range, which is hugely important when determining the
post-mortem interval (time since death). Time of death can be calculated to within
a margin of error of just 24 hours. Entomology can also be useful in
toxicological investigation, by the analysis of flesh eating insects, and human
DNA can be extracted from blood sucking insects to help identify suspects.

 

ENVIRONMENT & THE BODY FARM

            The dry
skeletal remains signal the end of the decomposition process if it occurs in
ideal conditions. If certain extreme conditions are present, it may halt
aspects of decomposition so greatly that the cadaver is in a state of natural
preservation. As with all biological processes, there is a long list of
variable factors that affect decomposition. Primarily studied, environmental
factors, such as temperature, exposure to oxygen or sunlight, burial, soil
type, rainfall, humidity or submersion in water. The possible number of other
variables is almost impossible to predict but some stand out for forensic
significance. The cause of death can hugely impact decomposition, as can any artificial
embalming procedures. The physical body weight is crucial as more obese
cadavers decay much quicker than thinner ones, due to the quantity of adipose
tissue. (Di Maio & Di Maio, 2001)

            Over the last
40 years, forensic science has benefited from a range of discoveries in
taphonomy research. Many of these discoveries are thanks to specialised
research facilities known as body farms. There are seven such academic sites in
the US and proposals in process in Australia, Netherlands and UK. Before the
advent of human body farms, pig carcasses were studied due to their
physiological similarities to humans. Dr. Bill Bass founded the Anthropological
Research Facility at the University of Tennessee in the late 1970’s, despite
much opposition from protestors and the public in Knoxville. Body farms focus
on the importance of the environment in the understanding of taphonomy on a
forensic level. Donated cadavers are placed in a variety of environments, for
example in the boot of a car or submerged in a river. They are allowed to
decompose naturally while scientists from a range of forensic disciplines study
them. This has been a huge step in progress in this discipline, but scientists
admit there is still a lot we don’t know. (Vass, 2001)

            Dr. Anna
Williams of Huddersfield University and Prof. John Cassella of Staffordshire
University 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 donated
bodies is exclusively for the medical profession. Dr. Williams is in
negotiation with the Human Tissue Authority to include taphonomy research in
their ‘scheduled purposes’. This would make it possible to get a HTA license to
open a ‘body farm’ facility for human taphonomic research in the UK. (Williams,
2015a) The importance of this research cannot be ignored. Society’s attitudes
and religious beliefs cannot block progress in such an essential area. (Vass, 2001)