The stages of death of a human being have medical, biochemical and
legal
Law is a set of rules that are created and are law enforcement, enforceable by social or governmental institutions to regulate behavior,Robertson, ''Crimes against humanity'', 90. with its precise definition a matter of longstanding debate. ...
aspects. The term
taphonomy
Taphonomy is the study of how organisms decay and become fossilized or preserved in the paleontological record. The term ''taphonomy'' (from Greek , 'burial' and , 'law') was introduced to paleontology in 1940 by Soviet scientist Ivan Efremov t ...
from
palaeontology applies to the fate of all kinds of remains of organisms, with forensic taphonomy concerned for remains of the
human body.
History
The academic study of death is called
thanatology
Thanatology is the scientific study of death and the losses brought about as a result. It investigates the mechanisms and forensic aspects of death, such as bodily changes that accompany death and the postmortem period, as well as wider psycho ...
, a field pioneered by
Élie Metchnikoff
Ilya Ilyich Mechnikov (russian: Илья Ильич Мечников; – 15 July 1916), also spelled Élie Metchnikoff, was a Russian zoologist best known for his pioneering research in immunology. Belkin, a Russian science historian, explain ...
in the early 20th century. Thanatology focuses on describing postmortem bodily modifications, as well as perspectives concerning psychosocial, medical, ethical, and spiritual aspects of death.
Definition of death
Prior to the 1980s, the legal standard defined death as the absence of cardiopulmonary function including the loss of all vital signs. However, as medical technology advanced, there were situations where one might lose brain function and maintain cardiopulmonary function.
This led the
American Medical Association
The American Medical Association (AMA) is a professional association and lobbying group of physicians and medical students. Founded in 1847, it is headquartered in Chicago, Illinois. Membership was approximately 240,000 in 2016.
The AMA's sta ...
, the
American Bar Association
The American Bar Association (ABA) is a voluntary bar association of lawyers and law students, which is not specific to any jurisdiction in the United States. Founded in 1878, the ABA's most important stated activities are the setting of aca ...
in collaboration with the
National Conference of Commissioners on Uniform State Laws
The Uniform Law Commission (ULC), also called the National Conference of Commissioners on Uniform State Laws, is a non-profit, American unincorporated association. Established in 1892, the ULC aims to provide U.S. states (plus the District of C ...
to come together in the 1980s to expand the definition of death through the Uniform Determination of Death Act (UDDA).
Under this law, death can be defined as the loss of cardiopulmonary function or the loss of brain function including the brainstem and cortex.
Clinical signs and stages of death
Signs of death or strong indications that a
warm-blooded animal is no longer alive are:
*
Respiratory arrest
Respiratory arrest is a sickness caused by apnea (cessation of breathing) or respiratory dysfunction severe enough it will not sustain the body (such as agonal breathing). Prolonged apnea refers to a patient who has stopped breathing for a long p ...
(no
breathing)
*
Cardiac arrest
Cardiac arrest is when the heart suddenly and unexpectedly stops beating. It is a medical emergency that, without immediate medical intervention, will result in sudden cardiac death within minutes. Cardiopulmonary resuscitation (CPR) and possib ...
(no
pulse
In medicine, a pulse represents the tactile arterial palpation of the cardiac cycle (heartbeat) by trained fingertips. The pulse may be palpated in any place that allows an artery to be compressed near the surface of the body, such as at the n ...
)
*
Brain death (no neuronal activity)
The heart and lungs are vital organs for human life due to their ability to properly oxygenate human blood (lungs) and distribute this blood to all vital organs (heart). Hence failure of the heart to pump blood or the lungs to obtain oxygen can lead to a cardiopulmonary death where the heart stops pumping and there is no pulse. In the brain, this can be manifested by a hypoxic state which leads to cerebral edema and thus an increase in intracranial pressure. The rise in intracranial pressure can lead to further disruption in cerebral blood flow, leading to necrosis or tissue death. The aforementioned mechanism is the most common cause of brain death, however this increase in intracranial pressure does not always occur due to an arrest in cardiopulmonary function. Traumatic brain injuries and subarachnoid hemorrhages can also increase the intracranial pressure in the brain leading to a cessation of brain function and hence death. While cardiopulmonary death can be easily assessed by looking for the presence of a pulse, or identifying electrical activity through EKG tracings, assessment of brain death is slightly more nuanced. Per the United Kingdom Medical Royal Colleges, a diagnosis of brain death is a two-fold process including 1) identifying the cause of irreversible brain damage and excluding reversible causes of brain damage and 2) conducting a series of clinical and laboratory tests to assess brain stem function.
The definition of
legal death
Legal death is the recognition under the law of a particular jurisdiction that a person is no longer alive. In most cases, a doctor's declaration of death (variously called) or the identification of a corpse is a legal requirement for such recognit ...
, and its formal documentation in a
death certificate
A death certificate is either a legal document issued by a medical practitioner which states when a person died, or a document issued by a government civil registration office, that declares the date, location and cause of a person's death, as ...
, vary according to the jurisdiction. The certification applies to somatic death, corresponding to death of the person, which has varying definitions but most commonly describes a lack of vital signs and brain function. Death at the level of cells, called molecular death or cell death, follows a matter of hours later. These distinctions, and the independence of physicians certifying legal death, are significant in
organ procurement
Organ procurement (also called organ harvesting) is a surgical procedure that removes organs or tissues for reuse, typically for organ transplantation.
Procedures
If the organ donor is human, most countries require that the donor be legally de ...
.
Post-mortem changes
![Postmortem changes of the eye](https://upload.wikimedia.org/wikipedia/commons/d/d0/Postmortem_changes_of_the_eye.jpg)
Post-mortem changes refer to the series of changes that occur to a body after death. These changes can generally be divided between early post-mortem changes and late post-mortem changes (also known as decomposition).
These changes occur along a continuum and can be helpful in determining the post-mortem interval, which is the time between death and examination.
The stages that follow shortly after death are:
*
Corneal opacity
The human cornea is a transparent membrane which allows light to pass through it. The word corneal opacification literally means loss of normal transparency of cornea. The term corneal opacity is used particularly for the loss of transparency of c ...
or "clouding"
* , paleness which happens in the first 15–120 minutes after death
* , the reduction in body temperature following death. This is generally a steady decline until matching ambient temperature
* , the limbs of the corpse become stiff (Latin ''rigor'') and difficult to move or manipulate
* , or dependent lividity, a settling of the blood in the lower (dependent) portion of the body
*
Putrefaction
Putrefaction is the fifth stage of death, following pallor mortis, algor mortis, rigor mortis, and livor mortis. This process references the breaking down of a body of an animal, such as a human, post-mortem. In broad terms, it can be view ...
, the beginning signs of decomposition
Of these, with obvious mortal damage to the body, the textbook conclusive signs of death clear to a lay person are: ''algor mortis'', ''rigor mortis'', ''livor mortis'', and putrefaction.
The cardinal signs of death may refer to the ending of breathing, heartbeat and circulation, or to ''algor mortis'', ''livor mortis'' and ''rigor mortis''; the adoption of brain death as a definition has lessened the centrality of these signs.
In a clearer contemporary terminology, ''algor mortis'', ''livor mortis'' and ''rigor mortis'' are called "early postmortem" changes, in distinction from the "immediate postmortem" changes associated with the cessation of bodily functions, as indicated by
vital signs
Vital signs (also known as vitals) are a group of the four to six most crucial medical signs that indicate the status of the body's vital (life-sustaining) functions. These measurements are taken to help assess the general physical health of a ...
. With an
ophthalmoscope
Ophthalmoscopy, also called funduscopy, is a test that allows a health professional to see inside the fundus of the eye and other structures using an ophthalmoscope (or funduscope). It is done as part of an eye examination and may be done as part ...
, changes to the blood in the
retina
The retina (from la, rete "net") is the innermost, light-sensitive layer of tissue of the eye of most vertebrates and some molluscs. The optics of the eye create a focused two-dimensional image of the visual world on the retina, which then ...
are quickly visible.
Those stages are followed, in taphonomy, by
*
Decomposition
Decomposition or rot is the process by which dead organic substances are broken down into simpler organic or inorganic matter such as carbon dioxide, water, simple sugars and mineral salts. The process is a part of the nutrient cycle and is e ...
, the reduction into simpler forms of matter, accompanied by a strong, unpleasant odor.
*
Skeletonization
Skeletonization is the state of a dead organism after undergoing decomposition.The Australian Museum. (2018). Decomposition-Body Changes. Retrieved from: https://australianmuseum.net.au/about/history/exhibitions/death-the-last-taboo/decomposit ...
, the end of decomposition, where all soft tissues have decomposed, leaving only the skeleton.
*
Fossil
A fossil (from Classical Latin , ) is any preserved remains, impression, or trace of any once-living thing from a past geological age. Examples include bones, shells, exoskeletons, stone imprints of animals or microbes, objects preserved ...
ization, the natural preservation of the skeletal remains formed over a very long period. This stage may not occur, depending on the circumstances and the conditions of the surrounding environment.
Decomposition stages
Descriptions of
decomposition
Decomposition or rot is the process by which dead organic substances are broken down into simpler organic or inorganic matter such as carbon dioxide, water, simple sugars and mineral salts. The process is a part of the nutrient cycle and is e ...
have had varying numbers of discrete stages. A 5-stage process developed by Galloway and colleagues that is commonly used in
forensic pathology
Forensic pathology is pathology that focuses on determining the cause of death by examining a corpse. A post mortem examination is performed by a medical examiner or forensic pathologist, usually during the investigation of criminal law cases ...
is detailed below:
* Stage 1: Fresh – about half of bodies show signs of lividity and no signs of insects.
* Stage 2: Early Decomposition – Bacteria grow throughout the body, releasing gases, including
cadaverine
Cadaverine is an organic compound with the formula (CH2)5(NH2)2. Classified as diamine, it is a colorless liquid with an unpleasant odor. It is present in small quantities in living organisms but is often associated with the putrefaction of an ...
, which in turn
bloat the body and cause an unpleasant odor.
* Stage 3: Advanced Decomposition – This stage brings further discoloration to the body. The gases from bacterial decay begin to escape, causing a strong odor.
* Stage 4: Skeletonization – The internal organs liquefy and the body begins to dry out.
* Stage 5: Extreme Decomposition – Advancing of the skeletonization with bleaching, exfoliation, and loss of wide portions of long bone.
See also
*
Suspended animation
Suspended animation is the temporary (short- or long-term) slowing or stopping of biological function so that physiological capabilities are preserved. It may be either hypometabolic or ametabolic in nature. It may be induced by either endogen ...
*
Lazarus syndrome
Lazarus syndrome (the Lazarus heart), also known as autoresuscitation after failed cardiopulmonary resuscitation, is the spontaneous return of a normal cardiac rhythm after failed attempts at resuscitation. It is also the spontaneous return o ...
*
Cadaveric spasm
Cadaveric spasm, also known as postmortem spasm, instantaneous rigor mortis, cataleptic rigidity, or instantaneous rigidity, is a rare form of muscular stiffening that occurs at the moment of death and persists into the period of rigor mortis. Cad ...
References
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Medical aspects of death