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Death is the irreversible cessation of all biological functions that sustain an
organism In biology, an organism () is any living system that functions as an individual entity. All organisms are composed of cells (cell theory). Organisms are classified by taxonomy into groups such as multicellular animals, plants, and ...
. For organisms with a brain, death can also be defined as the irreversible cessation of functioning of the whole brain, including brainstem, and brain death is sometimes used as a legal definition of death. The remains of a former organism normally begin to
decompose 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 ...
shortly after death. Death is an inevitable process that eventually occurs in almost all organisms. Death is generally applied to whole organisms; the similar process seen in individual components of an organism, such as cells or tissues, is necrosis. Something that is not considered an organism, such as a
virus A virus is a submicroscopic infectious agent that replicates only inside the living cells of an organism. Viruses infect all life forms, from animals and plants to microorganisms, including bacteria and archaea. Since Dmitri Ivanovsk ...
, can be physically destroyed but is not said to die. As of the early 21st century, over 150,000 humans die each day, with ageing being by far the most common
cause of death In law, medicine, and statistics, cause of death is an official determination of conditions resulting in a human's death, which may be recorded on a death certificate. A cause of death is determined by a medical examiner. The cause of death is ...
. Many cultures and religions have the idea of an afterlife, and also may hold the idea of
judgement Judgement (or US spelling judgment) is also known as ''adjudication'', which means the evaluation of evidence to make a decision. Judgement is also the ability to make considered decisions. The term has at least five distinct uses. Aristotle s ...
of good and bad deeds in one's life ( heaven, hell,
karma Karma (; sa, कर्म}, ; pi, kamma, italic=yes) in Sanskrit means an action, work, or deed, and its effect or consequences. In Indian religions, the term more specifically refers to a principle of cause and effect, often descriptivel ...
).


Diagnosis


Problems of definition

The concept of death is a key to human understanding of the phenomenon. There are many scientific approaches and various interpretations of the concept. Additionally, the advent of life-sustaining therapy and the numerous criteria for defining death from both a medical and legal standpoint, have made it difficult to create a single unifying definition. One of the challenges in defining death is in distinguishing it from
life Life is a quality that distinguishes matter that has biological processes, such as Cell signaling, signaling and self-sustaining processes, from that which does not, and is defined by the capacity for Cell growth, growth, reaction to Stimu ...
. As a point in time, death would seem to refer to the moment at which life ends. Determining when death has occurred is difficult, as cessation of life functions is often not simultaneous across organ systems. Such determination, therefore, requires drawing precise conceptual boundaries between life and death. This is difficult, due to there being little consensus on how to define life. It is possible to define life in terms of consciousness. When consciousness ceases, an organism can be said to have died. One of the flaws in this approach is that there are many organisms that are alive but probably not conscious (for example, single-celled organisms). Another problem is in defining consciousness, which has many different definitions given by modern scientists, psychologists and philosophers. Additionally, many religious traditions, including
Abrahamic The Abrahamic religions are a group of religions centered around worship of the God of Abraham. Abraham, a Hebrew patriarch, is extensively mentioned throughout Abrahamic religious scriptures such as the Bible and the Quran. Jewish tradition ...
and
Dharmic Dharma (; sa, धर्म, dharma, ; pi, dhamma, italic=yes) is a key concept with multiple meanings in Indian religions, such as Hinduism, Buddhism, Jainism, Sikhism and others. Although there is no direct single-word translation for '' ...
traditions, hold that death does not (or may not) entail the end of consciousness. In certain cultures, death is more of a process than a single event. It implies a slow shift from one spiritual state to another. Other definitions for death focus on the character of cessation of organismic functioning and a human death which refers to irreversible loss of personhood. More specifically, death occurs when a living entity experiences irreversible cessation of all functioning. As it pertains to human life, death is an irreversible process where someone loses their existence as a person.Historically, attempts to define the exact moment of a human's death have been subjective, or imprecise. Death was once defined as the cessation of
heart The heart is a muscular organ in most animals. This organ pumps blood through the blood vessels of the circulatory system. The pumped blood carries oxygen and nutrients to the body, while carrying metabolic waste such as carbon dioxide to t ...
beat (
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 poss ...
) and of
breath Breathing (or ventilation) is the process of moving air into and from the lungs to facilitate gas exchange with the internal environment, mostly to flush out carbon dioxide and bring in oxygen. All aerobic creatures need oxygen for cell ...
ing, but the development of
CPR Cardiopulmonary resuscitation (CPR) is an emergency procedure consisting of chest compressions often combined with artificial ventilation in an effort to manually preserve intact brain function until further measures are taken to restore sponta ...
and prompt defibrillation have rendered that definition inadequate because breathing and heartbeat can sometimes be restarted. This type of death where circulatory and respiratory arrest happens is known as the circulatory definition of death (DCDD). Proponents of the DCDD believe that this definition is reasonable because a person with permanent loss of circulatory and respiratory function should be considered dead. Critics of this definition state that while cessation of these functions may be permanent, it does not mean the situation is irreversible, because if CPR was applied, the person could be revived. Thus, the arguments for and against the DCDD boil down to a matter of defining the actual words "permanent" and "irreversible," which further complicates the challenge of defining death. Furthermore, events which were causally linked to death in the past no longer kill in all circumstances; without a functioning heart or lungs, life can sometimes be sustained with a combination of life support devices, organ transplants and
artificial pacemaker An artificial cardiac pacemaker (or artificial pacemaker, so as not to be confused with the natural cardiac pacemaker) or pacemaker is a medical device that generates electrical impulses delivered by electrodes to the chambers of the heart eit ...
s. Today, where a definition of the moment of death is required, doctors and coroners usually turn to "brain death" or "biological death" to define a person as being dead; people are considered dead when the electrical activity in their brain ceases. It is presumed that an end of electrical activity indicates the end of
consciousness Consciousness, at its simplest, is sentience and awareness of internal and external existence. However, the lack of definitions has led to millennia of analyses, explanations and debates by philosophers, theologians, linguisticians, and scien ...
. Suspension of consciousness must be permanent, and not transient, as occurs during certain
sleep Sleep is a sedentary state of mind and body. It is characterized by altered consciousness, relatively inhibited sensory activity, reduced muscle activity and reduced interactions with surroundings. It is distinguished from wakefulness by a de ...
stages, and especially a coma. In the case of sleep, EEGs can easily tell the difference. The category of "brain death" is seen as problematic by some scholars. For instance, Dr. Franklin Miller, senior faculty member at the Department of Bioethics, National Institutes of Health, notes: "By the late 1990s... the equation of brain death with death of the human being was increasingly challenged by scholars, based on evidence regarding the array of biological functioning displayed by patients correctly diagnosed as having this condition who were maintained on mechanical ventilation for substantial periods of time. These patients maintained the ability to sustain circulation and respiration, control temperature, excrete wastes, heal wounds, fight infections and, most dramatically, to gestate fetuses (in the case of pregnant "brain-dead" women)." While "brain death" is viewed as problematic by some scholars, there are certainly proponents of it that believe this definition of death is the most reasonable for distinguishing life from death. The reasoning behind the support for this definition is that brain death has a set of criteria that is reliable and reproducible. Also, the brain is crucial in determining our identity or who we are as human beings. The distinction should be made that "brain death" cannot be equated with one who is in a vegetative state or coma, in that the former situation describes a state that is beyond recovery. Those people maintaining that only the
neo-cortex The neocortex, also called the neopallium, isocortex, or the six-layered cortex, is a set of layers of the mammalian cerebral cortex involved in higher-order brain functions such as sensory perception, cognition, generation of motor commands, sp ...
of the brain is necessary for consciousness sometimes argue that only electrical activity should be considered when defining death. Eventually it is possible that the criterion for death will be the permanent and irreversible loss of cognitive function, as evidenced by the death of the
cerebral cortex The cerebral cortex, also known as the cerebral mantle, is the outer layer of neural tissue of the cerebrum of the brain in humans and other mammals. The cerebral cortex mostly consists of the six-layered neocortex, with just 10% consistin ...
. All hope of recovering human thought and
personality Personality is the characteristic sets of behaviors, cognitions, and emotional patterns that are formed from biological and environmental factors, and which change over time. While there is no generally agreed-upon definition of personality, m ...
is then gone given current and foreseeable medical technology. At present, in most places the more conservative definition of death – irreversible cessation of electrical activity in the whole brain, as opposed to just in the neo-cortex – has been adopted (for example the Uniform Determination Of Death Act in the United States). In 2005, the
Terri Schiavo case The Terri Schiavo case was a series of court and legislative actions in the United States from 1998 to 2005, regarding the care of Theresa Marie Schiavo (née Schindler) (; December 3, 1963 – March 31, 2005), a woman in an irreversible ...
brought the question of brain death and artificial sustenance to the front of American politics. Even by whole-brain criteria, the determination of brain death can be complicated. EEGs can detect spurious electrical impulses, while certain drugs,
hypoglycemia Hypoglycemia, also called low blood sugar, is a fall in blood sugar to levels below normal, typically below 70 mg/dL (3.9 mmol/L). Whipple's triad is used to properly identify hypoglycemic episodes. It is defined as blood glucose bel ...
, hypoxia, or
hypothermia Hypothermia is defined as a body core temperature below in humans. Symptoms depend on the temperature. In mild hypothermia, there is shivering and mental confusion. In moderate hypothermia, shivering stops and confusion increases. In severe ...
can suppress or even stop brain activity on a temporary basis. Because of this, hospitals have protocols for determining brain death involving EEGs at widely separated intervals under defined conditions. In the past, adoption of this whole-brain definition was a conclusion of the President's Commission for the Study of Ethical Problems in Medicine and Biomedical and Behavioral Research in 1980. They concluded that this approach to defining death sufficed in reaching a uniform definition nationwide. A multitude of reasons were presented to support this definition including: uniformity of standards in law for establishing death; consumption of a family's fiscal resources for artificial life support; and legal establishment for equating brain death with death in order to proceed with organ donation.Aside from the issue of support of or dispute against brain death, there is another inherent problem in this categorical definition: the variability of its application in medical practice. In 1995, the American Academy of Neurology (AAN), established a set of criteria that became the medical standard for diagnosing neurologic death. At that time, three clinical features had to be satisfied in order to determine "irreversible cessation" of the total brain including: coma with clear etiology, cessation of breathing, and lack of brainstem reflexes. This set of criteria was then updated again most recently in 2010, but substantial discrepancies still remain across hospitals and medical specialties. The problem of defining death is especially imperative as it pertains to the
dead donor rule Prior to the introduction of brain death into law in the mid to late 1970s, all organ transplants from cadaveric donors came from non-heart-beating donors (NHBDs). Donors after brain death (DBD) (beating heart cadavers), however, led to better resu ...
, which could be understood as one of the following interpretations of the rule: there must be an official declaration of death in a person before starting organ procurement or that organ procurement cannot result in death of the donor. A great deal of controversy has surrounded the definition of death and the dead donor rule. Advocates of the rule believe the rule is legitimate in protecting organ donors while also countering against any moral or legal objection to organ procurement. Critics, on the other hand, believe that the rule does not uphold the best interests of the donors and that the rule does not effectively promote organ donation.


Signs

Signs of death or strong indications that a warm-blooded animal is no longer alive are: * Respiratory arrest (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 poss ...
(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 stages that follow after death are: * , paleness which happens in 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 * , 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 *
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


Legal

The death of a person has legal consequences that may vary between different jurisdictions. 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 ...
is issued in most jurisdictions, either by a doctor, or by an administrative office upon presentation of a doctor's declaration of death.


Misdiagnosed

There are many anecdotal references to people being declared dead by physicians and then "coming back to life", sometimes days later in their own coffin, or when
embalming Embalming is the art and science of preserving human remains by treating them (in its modern form with chemicals) to forestall decomposition. This is usually done to make the deceased suitable for public or private viewing as part of the funeral ...
procedures are about to begin. From the mid-18th century onwards, there was an upsurge in the public's fear of being mistakenly buried alive, and much debate about the uncertainty of the signs of death. Various suggestions were made to test for signs of life before burial, ranging from pouring vinegar and pepper into the corpse's mouth to applying red hot pokers to the feet or into the rectum. Writing in 1895, the physician J.C. Ouseley claimed that as many as 2,700 people were buried prematurely each year in England and Wales, although others estimated the figure to be closer to 800. In cases of electric shock,
cardiopulmonary resuscitation Cardiopulmonary resuscitation (CPR) is an emergency procedure consisting of chest compressions often combined with artificial ventilation in an effort to manually preserve intact brain function until further measures are taken to restore spon ...
(CPR) for an hour or longer can allow stunned nerves to recover, allowing an apparently dead person to survive. People found unconscious under icy water may survive if their faces are kept continuously cold until they arrive at an emergency room. This "diving response", in which metabolic activity and oxygen requirements are minimal, is something humans share with cetaceans called the
mammalian diving reflex The diving reflex, also known as the diving response and mammalian diving reflex, is a set of physiological responses to immersion that overrides the basic homeostatic reflexes, and is found in all air-breathing vertebrates studied to date. It o ...
. As medical technologies advance, ideas about when death occurs may have to be re-evaluated in light of the ability to restore a person to vitality after longer periods of apparent death (as happened when CPR and defibrillation showed that cessation of heartbeat is inadequate as a decisive indicator of death). The lack of electrical brain activity may not be enough to consider someone scientifically dead. Therefore, the concept of information-theoretic death has been suggested as a better means of defining when true death occurs, though the concept has few practical applications outside the field of
cryonics Cryonics (from el, κρύος ''kryos'' meaning 'cold') is the low-temperature freezing (usually at ) and storage of human remains, with the speculative hope that resurrection may be possible in the future. Cryonics is regarded with skepticis ...
. There have been some scientific attempts to bring dead organisms back to life, but with limited success.


Causes

The leading cause of human death in
developing countries A developing country is a sovereign state with a lesser developed industrial base and a lower Human Development Index (HDI) relative to other countries. However, this definition is not universally agreed upon. There is also no clear agreem ...
is
infectious disease An infection is the invasion of tissues by pathogens, their multiplication, and the reaction of host tissues to the infectious agent and the toxins they produce. An infectious disease, also known as a transmissible disease or communicable di ...
. The leading causes in
developed countries A developed country (or industrialized country, high-income country, more economically developed country (MEDC), advanced country) is a sovereign state that has a high quality of life, developed economy and advanced technological infrastruct ...
are
atherosclerosis Atherosclerosis is a pattern of the disease arteriosclerosis in which the wall of the artery develops abnormalities, called lesions. These lesions may lead to narrowing due to the buildup of atheromatous plaque. At onset there are usually no s ...
( heart disease and stroke),
cancer Cancer is a group of diseases involving abnormal cell growth with the potential to invade or spread to other parts of the body. These contrast with benign tumors, which do not spread. Possible signs and symptoms include a lump, abnormal b ...
, and other diseases related to
obesity Obesity is a medical condition, sometimes considered a disease, in which excess body fat has accumulated to such an extent that it may negatively affect health. People are classified as obese when their body mass index (BMI)—a person's ...
and aging. By an extremely wide margin, the largest unifying cause of death in the developed world is biological aging, leading to various complications known as aging-associated diseases. These conditions cause loss of
homeostasis In biology, homeostasis (British also homoeostasis) (/hɒmɪə(ʊ)ˈsteɪsɪs/) is the state of steady internal, physical, and chemical conditions maintained by living systems. This is the condition of optimal functioning for the organism and ...
, leading to
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 poss ...
, causing loss of
oxygen Oxygen is the chemical element with the symbol O and atomic number 8. It is a member of the chalcogen group in the periodic table, a highly reactive nonmetal, and an oxidizing agent that readily forms oxides with most elements as ...
and nutrient supply, causing irreversible deterioration of the
brain A brain is an organ that serves as the center of the nervous system in all vertebrate and most invertebrate animals. It is located in the head, usually close to the sensory organs for senses such as vision. It is the most complex organ in a ve ...
and other tissues. Of the roughly 150,000 people who die each day across the globe, about two thirds die of age-related causes. In industrialized nations, the proportion is much higher, approaching 90%. With improved medical capability,
dying Dying is the final stage of life which will eventually lead to death. Diagnosing dying is a complex process of clinical decision-making, and most practice checklists facilitating this diagnosis are based on cancer diagnoses. Signs of dying ...
has become a condition to be managed. Home deaths, once commonplace, are now rare in the developed world. In
developing nations A developing country is a sovereign state with a lesser developed industrial base and a lower Human Development Index (HDI) relative to other countries. However, this definition is not universally agreed upon. There is also no clear agreeme ...
, inferior sanitary conditions and lack of access to modern medical technology makes death from infectious diseases more common than in
developed countries A developed country (or industrialized country, high-income country, more economically developed country (MEDC), advanced country) is a sovereign state that has a high quality of life, developed economy and advanced technological infrastruct ...
. One such disease is
tuberculosis Tuberculosis (TB) is an infectious disease usually caused by '' Mycobacterium tuberculosis'' (MTB) bacteria. Tuberculosis generally affects the lungs, but it can also affect other parts of the body. Most infections show no symptoms, i ...
, a bacterial disease which killed 1.8M people in 2015.
Malaria Malaria is a mosquito-borne infectious disease that affects humans and other animals. Malaria causes symptoms that typically include fever, tiredness, vomiting, and headaches. In severe cases, it can cause jaundice, seizures, coma, or death. S ...
causes about 400–900M cases of fever and 1–3M deaths annually. AIDS death toll in Africa may reach 90–100M by 2025. According to
Jean Ziegler Jean Ziegler (; born Hans Ziegler, 19 April 1934) is a Swiss former professor of sociology at the University of Geneva and the Sorbonne, Paris, and former vice-president of the Advisory Committee to the United Nations Human Rights Council. He ...
(
United Nations The United Nations (UN) is an intergovernmental organization whose stated purposes are to maintain international peace and security, develop friendly relations among nations, achieve international cooperation, and be a centre for harmoniz ...
Special Reporter on the Right to Food, 2000 – Mar 2008), mortality due to
malnutrition Malnutrition occurs when an organism gets too few or too many nutrients, resulting in health problems. Specifically, it is "a deficiency, excess, or imbalance of energy, protein and other nutrients" which adversely affects the body's tissues ...
accounted for 58% of the total mortality rate in 2006. Ziegler says worldwide approximately 62M people died from all causes and of those deaths more than 36M died of hunger or diseases due to deficiencies in micronutrients.
Tobacco Tobacco is the common name of several plants in the genus '' Nicotiana'' of the family Solanaceae, and the general term for any product prepared from the cured leaves of these plants. More than 70 species of tobacco are known, but the ...
smoking killed 100 million people worldwide in the 20th century and could kill 1 billion people around the world in the 21st century, a
World Health Organization The World Health Organization (WHO) is a specialized agency of the United Nations responsible for international public health. The WHO Constitution states its main objective as "the attainment by all peoples of the highest possible level of ...
report warned. Many leading developed world causes of death can be postponed by
diet Diet may refer to: Food * Diet (nutrition), the sum of the food consumed by an organism or group * Dieting, the deliberate selection of food to control body weight or nutrient intake ** Diet food, foods that aid in creating a diet for weight loss ...
and
physical activity Physical activity is defined as any voluntary bodily movement produced by skeletal muscles that requires energy expenditure.Global Recommendations on Physical Activity for Health, 2009. World Health Organization. Geneva, Switzerland. Accessed 13/ ...
, but the accelerating incidence of disease with age still imposes limits on human longevity. The evolutionary cause of aging is, at best, only just beginning to be understood. It has been suggested that direct intervention in the aging process may now be the most effective intervention against major causes of death. Selye proposed a unified non-specific approach to many causes of death. He demonstrated that
stress Stress may refer to: Science and medicine * Stress (biology), an organism's response to a stressor such as an environmental condition * Stress (linguistics), relative emphasis or prominence given to a syllable in a word, or to a word in a phrase ...
decreases adaptability of an organism and proposed to describe the adaptability as a special resource, ''adaptation energy''. The animal dies when this resource is exhausted.Selye, H. (1938). Experimental evidence supporting the conception of "adaptation energy", Am. J. Physiol. 123 (1938), 758–765. Selye assumed that the adaptability is a finite supply, presented at birth. Later on, Goldstone proposed the concept of a production or income of adaptation energy which may be stored (up to a limit), as a capital reserve of adaptation. In recent works, adaptation energy is considered as an internal coordinate on the "dominant path" in the model of adaptation. It is demonstrated that oscillations of well-being appear when the reserve of adaptability is almost exhausted. In 2012, suicide overtook car crashes for leading causes of human injury deaths in the U.S., followed by poisoning, falls, and murder. Causes of death are different in different parts of the world. In high-income and middle income countries nearly half up to more than two thirds of all people live beyond the age of 70 and predominantly die of chronic diseases. In low-income countries, where less than one in five of all people reach the age of 70, and more than a third of all deaths are among children under 15, people predominantly die of infectious diseases.


Autopsy

An autopsy, also known as a ''postmortem examination'' or an ''obduction'', is a
medical procedure A medical procedure is a course of action intended to achieve a result in the delivery of healthcare. A medical procedure with the intention of determining, measuring, or diagnosing a patient condition or parameter is also called a medical test. ...
that consists of a thorough examination of a human
corpse A cadaver or corpse is a dead human body that is used by medical students, physicians and other scientists to study anatomy, identify disease sites, determine causes of death, and provide tissue to repair a defect in a living human being. Stud ...
to determine the cause and manner of a person's death and to evaluate any
disease A disease is a particular abnormal condition that negatively affects the structure or function of all or part of an organism, and that is not immediately due to any external injury. Diseases are often known to be medical conditions that a ...
or injury that may be present. It is usually performed by a specialized medical doctor called a
pathologist Pathology is the study of the causes and effects of disease or injury. The word ''pathology'' also refers to the study of disease in general, incorporating a wide range of biology research fields and medical practices. However, when used in t ...
. Autopsies are either performed for legal or medical purposes. A forensic autopsy is carried out when the cause of death may be a criminal matter, while a clinical or academic autopsy is performed to find the medical cause of death and is used in cases of unknown or uncertain death, or for research purposes. Autopsies can be further classified into cases where external examination suffices, and those where the body is dissected and an internal examination is conducted. Permission from next of kin may be required for internal autopsy in some cases. Once an internal autopsy is complete the body is generally reconstituted by sewing it back together. Autopsy is important in a medical environment and may shed light on mistakes and help improve practices. A necropsy, which is not always a medical procedure, was a term previously used to describe an unregulated postmortem examination. In modern times, this term is more commonly associated with the corpses of animals.


Senescence

Senescence refers to a scenario when a living being is able to survive all calamities, but eventually dies due to causes relating to old age. Animal and plant cells normally reproduce and function during the whole period of natural existence, but the aging process derives from deterioration of cellular activity and ruination of regular functioning. Aptitude of cells for gradual deterioration and mortality means that cells are naturally sentenced to stable and long-term loss of living capacities, even despite continuing metabolic reactions and viability. In the United Kingdom, for example, nine out of ten of all the deaths that occur on a daily basis relates to senescence, while around the world it accounts for two-thirds of 150,000 deaths that take place daily. Almost all
animal Animals are multicellular, eukaryotic organisms in the Kingdom (biology), biological kingdom Animalia. With few exceptions, animals Heterotroph, consume organic material, Cellular respiration#Aerobic respiration, breathe oxygen, are Motilit ...
s who survive external hazards to their biological functioning eventually die from biological aging, known in life sciences as "senescence". Some organisms experience
negligible senescence Negligible senescence is a term coined by biogerontologist Caleb Finch to denote organisms that do not exhibit evidence of biological aging (senescence), such as measurable reductions in their reproductive capability, measurable functional decline ...
, even exhibiting biological immortality. These include the jellyfish ''
Turritopsis dohrnii ''Turritopsis dohrnii'', also known as the immortal jellyfish, is a species of small, biologically immortal jellyfish found worldwide in temperate to tropic waters. It is one of the few known cases of animals capable of reverting completely to ...
'', the hydra, and the
planarian A planarian is one of the many flatworms of the traditional class Turbellaria. It usually describes free-living flatworms of the order Tricladida (triclads), although this common name is also used for a wide number of free-living platyhelmint ...
. Unnatural causes of death include suicide and
predation Predation is a biological interaction where one organism, the predator, kills and eats another organism, its prey. It is one of a family of common feeding behaviours that includes parasitism and micropredation (which usually do not kill th ...
. From all causes, roughly 150,000 people die around the world each day. Of these, two thirds die directly or indirectly due to senescence, but in industrialized countries – such as the United States, the United Kingdom, and Germany – the rate approaches 90% (i.e., nearly nine out of ten of all deaths are related to senescence). Physiological death is now seen as a process, more than an event: conditions once considered indicative of death are now reversible. Where in the process a dividing line is drawn between life and death depends on factors beyond the presence or absence of
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 ...
. In general, clinical death is neither necessary nor sufficient for a determination 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 ...
. A patient with working
heart The heart is a muscular organ in most animals. This organ pumps blood through the blood vessels of the circulatory system. The pumped blood carries oxygen and nutrients to the body, while carrying metabolic waste such as carbon dioxide to t ...
and
lungs The lungs are the primary organs of the respiratory system in humans and most other animals, including some snails and a small number of fish. In mammals and most other vertebrates, two lungs are located near the backbone on either side ...
determined to be
brain dead Brain death is the permanent, irreversible, and complete loss of brain function which may include cessation of involuntary activity necessary to sustain life. It differs from persistent vegetative state, in which the person is alive and some aut ...
can be pronounced legally dead without clinical death occurring.


Cryonics

Cryonics (from Greek κρύος 'kryos-' meaning 'icy cold') is the low-temperature preservation of animals and humans who cannot be sustained by contemporary medicine, with the hope that healing and resuscitation may be possible in the future.
Cryopreservation Cryo-preservation or cryo-conservation is a process where organisms, organelles, cells, tissues, extracellular matrix, organs, or any other biological constructs susceptible to damage caused by unregulated chemical kinetics are preserved by co ...
of people or large animals is not reversible with current technology. The stated rationale for cryonics is that people who are considered dead by current legal or medical definitions may not necessarily be dead according to the more stringent information-theoretic definition of death. Some scientific literature is claimed to support the feasibility of cryonics. Medical science and cryobiologists generally regards cryonics with skepticism.


Life extension

Life extension refers to an increase in
maximum In mathematical analysis, the maxima and minima (the respective plurals of maximum and minimum) of a function, known collectively as extrema (the plural of extremum), are the largest and smallest value of the function, either within a given r ...
or average lifespan, especially in humans, by slowing down or reversing the processes of aging through
anti-aging The anti-aging movement is a social movement devoted to eliminating or reversing aging, or reducing the effects of it. A substantial portion of the attention of the movement is on the possibilities for life extension, but there is also interest in ...
measures. Despite the fact that aging is by far the most common cause of death worldwide, it is socially mostly ignored as such and seen as "necessary" and "inevitable" anyway, which is why little money is spent on research into anti-aging therapies, a phenomenon known as the pro-aging trance. Average lifespan is determined by vulnerability to
accident An accident is an unintended, normally unwanted event that was not directly caused by humans. The term ''accident'' implies that nobody should be blamed, but the event may have been caused by unrecognized or unaddressed risks. Most researche ...
s and age or lifestyle-related afflictions such as
cancer Cancer is a group of diseases involving abnormal cell growth with the potential to invade or spread to other parts of the body. These contrast with benign tumors, which do not spread. Possible signs and symptoms include a lump, abnormal b ...
, or cardiovascular disease. Extension of average lifespan can be achieved by good
diet Diet may refer to: Food * Diet (nutrition), the sum of the food consumed by an organism or group * Dieting, the deliberate selection of food to control body weight or nutrient intake ** Diet food, foods that aid in creating a diet for weight loss ...
, exercise and avoidance of hazards such as smoking. Maximum lifespan is also determined by the rate of aging for a species inherent in its
gene In biology, the word gene (from , ; "... Wilhelm Johannsen coined the word gene to describe the Mendelian units of heredity..." meaning ''generation'' or ''birth'' or ''gender'') can have several different meanings. The Mendelian gene is a b ...
s. Currently, the only widely recognized method of extending maximum lifespan is
calorie restriction Calorie restriction (caloric restriction or energy restriction) is a dietary regimen that reduces intake of energy from caloric foods & beverages without incurring malnutrition. "Reduce" can be defined relative to the subject's previous intake b ...
. Theoretically, extension of maximum lifespan can be achieved by reducing the rate of aging damage, by periodic replacement of damaged tissues, or by molecular repair or
rejuvenation Rejuvenation is a medical discipline focused on the practical reversal of the aging process. Rejuvenation is distinct from life extension. Life extension strategies often study the causes of aging and try to oppose those causes in order to slow ...
of deteriorated cells and tissues. A United States poll found that religious people and irreligious people, as well as men and women and people of different economic classes have similar rates of support for life extension, while Africans and Hispanics have higher rates of support than white people. 38 percent of the polled said they would desire to have their aging process cured. Researchers of life extension are a subclass of biogerontologists known as "biomedical gerontologists". They try to understand the nature of aging and they develop treatments to reverse aging processes or to at least slow them down, for the improvement of health and the maintenance of youthful vigor at every stage of life. Those who take advantage of life extension findings and seek to apply them upon themselves are called "life extensionists" or "longevists". The primary life extension strategy currently is to apply available anti-aging methods in the hope of living long enough to benefit from a complete cure to aging once it is developed.


Location

Before about 1930, most people in Western countries died in their own homes, surrounded by family, and comforted by clergy, neighbors, and doctors making
house call A house call is medical consultation performed by a doctor or other healthcare professionals visiting the home of a patient A patient is any recipient of health care services that are performed by healthcare professionals. The patient is ...
s. By the mid-20th century, half of all Americans died in a hospital. By the start of the 21st century, only about 20–25% of people in developed countries died outside of a medical institution. The shift away from dying at home towards dying in a professional medical environment has been termed the "Invisible Death". This shift occurred gradually over the years, until most deaths now occur outside the home.


Psychology

Death studies is a field within
psychology Psychology is the scientific study of mind and behavior. Psychology includes the study of conscious and unconscious phenomena, including feelings and thoughts. It is an academic discipline of immense scope, crossing the boundaries between ...
. Many people are afraid of
dying Dying is the final stage of life which will eventually lead to death. Diagnosing dying is a complex process of clinical decision-making, and most practice checklists facilitating this diagnosis are based on cancer diagnoses. Signs of dying ...
. Discussing, thinking about, or planning for their own deaths causes them discomfort. This fear may cause them to put off financial planning, preparing a
will and testament A will or testament is a legal document that expresses a person's (testator) wishes as to how their property ( estate) is to be distributed after their death and as to which person ( executor) is to manage the property until its final distributi ...
, or requesting help from a hospice organization. Different people have different responses to the idea of their own deaths. Philosopher
Galen Strawson Galen John Strawson (born 1952) is a British analytic philosopher and literary critic who works primarily on philosophy of mind, metaphysics (including free will, panpsychism, the mind-body problem, and the self), John Locke, David Hume, ...
writes that the death that many people wish for is an instant, painless, unexperienced annihilation. In this unlikely scenario, the person dies without realizing it and without being able to fear it. One moment the person is walking, eating, or sleeping, and the next moment, the person is dead. Strawson reasons that this type of death would not take anything away from the person, as he believes that a person cannot have a legitimate claim to ownership in the future.


Society and culture

In society, the nature of death and humanity's awareness of its own mortality has for millennia been a concern of the world's religious traditions and of philosophical inquiry. This includes belief in
resurrection Resurrection or anastasis is the concept of coming back to life after death. In a number of religions, a dying-and-rising god is a deity which dies and is resurrected. Reincarnation is a similar process hypothesized by other religions, whic ...
or an afterlife (associated with
Abrahamic religions The Abrahamic religions are a group of religions centered around worship of the God of Abraham. Abraham, a Hebrew patriarch, is extensively mentioned throughout Abrahamic religious scriptures such as the Bible and the Quran. Jewish tradition ...
),
reincarnation Reincarnation, also known as rebirth or transmigration, is the philosophical or religious concept that the non-physical essence of a living being begins a new life in a different physical form or body after biological death. Resurrection is ...
or rebirth (associated with Dharmic religions), or that consciousness permanently ceases to exist, known as
eternal oblivion Eternal oblivion (also referred to as non-existence or nothingness) is the philosophical or religious concept of one's consciousness forever ceasing upon death. Pamela Health and Jon Klimo write that this concept is mostly associated with religio ...
(associated with Secular humanism). Commemoration ceremonies after death may include various
mourning Mourning is the expression of an experience that is the consequence of an event in life involving loss, causing grief, occurring as a result of someone's death, specifically someone who was loved although loss from death is not exclusively ...
, funeral practices and ceremonies of honouring the deceased. The physical remains of a person, commonly known as a ''corpse'' or ''body'', are usually
interred Burial, also known as interment or inhumation, is a method of final disposition whereby a dead body is placed into the ground, sometimes with objects. This is usually accomplished by excavating a pit or trench, placing the deceased and objec ...
whole or
cremated Cremation is a method of final disposition of a dead body through burning. Cremation may serve as a funeral or post-funeral rite and as an alternative to burial. In some countries, including India and Nepal, cremation on an open-air pyre i ...
, though among the world's cultures there are a variety of other methods of mortuary disposal. In the English language, blessings directed towards a dead person include '' rest in peace'' (originally the
Latin Latin (, or , ) is a classical language belonging to the Italic branch of the Indo-European languages. Latin was originally a dialect spoken in the lower Tiber area (then known as Latium) around present-day Rome, but through the power of the ...
''requiescat in pace''), or its initialism RIP. Death is the center of many traditions and organizations; customs relating to death are a feature of every culture around the world. Much of this revolves around the care of the dead, as well as the afterlife and the disposal of bodies upon the onset of death. The
disposal of human corpses Disposal of human corpses, also called final disposition, is the practice and process of dealing with the remains of a deceased human being. Disposal methods may need to account for the fact that soft tissue will decompose relatively rapidly, wh ...
does, in general, begin with the last offices before significant time has passed, and ritualistic ceremonies often occur, most commonly interment or
cremation Cremation is a method of final disposition of a dead body through burning. Cremation may serve as a funeral or post-funeral rite and as an alternative to burial. In some countries, including India and Nepal, cremation on an open-air pyre is ...
. This is not a unified practice; in
Tibet Tibet (; ''Böd''; ) is a region in East Asia, covering much of the Tibetan Plateau and spanning about . It is the traditional homeland of the Tibetan people. Also resident on the plateau are some other ethnic groups such as Monpa, Taman ...
, for instance, the body is given a
sky burial Sky burial (, "bird-scattered") is a funeral practice in which a human corpse is placed on a mountaintop to decompose while exposed to the elements or to be eaten by scavenging animals, especially carrion birds. It is a specific type of the ...
and left on a mountain top. Proper preparation for death and techniques and ceremonies for producing the ability to transfer one's spiritual attainments into another body (
reincarnation Reincarnation, also known as rebirth or transmigration, is the philosophical or religious concept that the non-physical essence of a living being begins a new life in a different physical form or body after biological death. Resurrection is ...
) are subjects of detailed study in Tibet.
Mummification A mummy is a dead human or an animal whose soft tissues and organs have been preserved by either intentional or accidental exposure to chemicals, extreme cold, very low humidity, or lack of air, so that the recovered body does not decay furt ...
or
embalming Embalming is the art and science of preserving human remains by treating them (in its modern form with chemicals) to forestall decomposition. This is usually done to make the deceased suitable for public or private viewing as part of the funeral ...
is also prevalent in some cultures, to retard the rate of
decay Decay may refer to: Science and technology * Bit decay, in computing * Software decay, in computing * Distance decay, in geography * Decay time (fall time), in electronics Biology * Decomposition of organic matter * Tooth decay (dental caries ...
. Legal aspects of death are also part of many cultures, particularly the settlement of the deceased estate and the issues of
inheritance Inheritance is the practice of receiving private property, titles, debts, entitlements, privileges, rights, and obligations upon the death of an individual. The rules of inheritance differ among societies and have changed over time. Officia ...
and in some countries, inheritance taxation.
Capital punishment Capital punishment, also known as the death penalty, is the state-sanctioned practice of deliberately killing a person as a punishment for an actual or supposed crime, usually following an authorized, rule-governed process to conclude that t ...
is also a culturally divisive aspect of death. In most jurisdictions where capital punishment is carried out today, the death penalty is reserved for premeditated murder,
espionage Espionage, spying, or intelligence gathering is the act of obtaining secret or confidential information (intelligence) from non-disclosed sources or divulging of the same without the permission of the holder of the information for a tangib ...
,
treason Treason is the crime of attacking a state authority to which one owes allegiance. This typically includes acts such as participating in a war against one's native country, attempting to overthrow its government, spying on its military, its diplo ...
, or as part of military justice. In some countries, sexual crimes, such as
adultery Adultery (from Latin ''adulterium'') is extramarital sex that is considered objectionable on social, religious, moral, or legal grounds. Although the sexual activities that constitute adultery vary, as well as the social, religious, and legal ...
and
sodomy Sodomy () or buggery (British English) is generally anal or oral sex between people, or sexual activity between a person and a non-human animal ( bestiality), but it may also mean any non- procreative sexual activity. Originally, the term ''sod ...
, carry the death penalty, as do religious crimes such as
apostasy Apostasy (; grc-gre, ἀποστασία , 'a defection or revolt') is the formal disaffiliation from, abandonment of, or renunciation of a religion by a person. It can also be defined within the broader context of embracing an opinion that ...
, the formal renunciation of one's religion. In many retentionist countries, drug trafficking is also a capital offense. In China, human trafficking and serious cases of corruption are also punished by the death penalty. In militaries around the world
courts-martial A court-martial or court martial (plural ''courts-martial'' or ''courts martial'', as "martial" is a postpositive adjective) is a military court or a trial conducted in such a court. A court-martial is empowered to determine the guilt of memb ...
have imposed death sentences for offenses such as
cowardice Cowardice is a trait wherein excessive fear prevents an individual from taking a risk or facing danger. It is the opposite of courage. As a label, "cowardice" indicates a failure of character in the face of a challenge. One who succumbs to cowa ...
, desertion,
insubordination Insubordination is the act of willfully disobeying a lawful order of one's superior. It is generally a punishable offense in hierarchical organizations such as the armed forces, which depend on people lower in the chain of command obeying ord ...
, and mutiny. Death in warfare and in suicide attack also have cultural links, and the ideas of ''
dulce et decorum est pro patria mori ' is a line from the ''Odes'' (III.2.13) by the Roman lyric poet Horace. The line translates: "It is sweet and proper to die for one's country." The Latin word ''patria'' (homeland), literally meaning the country of one's fathers (in Latin, ...
'', mutiny punishable by death, grieving relatives of dead soldiers and death notification are embedded in many cultures. Recently in the western world, with the increase in terrorism following the
September 11 attacks The September 11 attacks, commonly known as 9/11, were four coordinated suicide terrorist attacks carried out by al-Qaeda against the United States on Tuesday, September 11, 2001. That morning, nineteen terrorists hijacked four commer ...
, but also further back in time with suicide bombings,
kamikaze , officially , were a part of the Japanese Special Attack Units of military aviators who flew suicide attacks for the Empire of Japan against Allied naval vessels in the closing stages of the Pacific campaign of World War II, intending t ...
missions in
World War II World War II or the Second World War, often abbreviated as WWII or WW2, was a world war that lasted from 1939 to 1945. It involved the vast majority of the world's countries—including all of the great powers—forming two opposing ...
and suicide missions in a host of other conflicts in history, death for a cause by way of suicide attack, and
martyrdom A martyr (, ''mártys'', "witness", or , ''marturia'', stem , ''martyr-'') is someone who suffers persecution and death for advocating, renouncing, or refusing to renounce or advocate, a religious belief or other cause as demanded by an externa ...
have had significant cultural impacts. Suicide in general, and particularly euthanasia, are also points of cultural debate. Both acts are understood very differently in different cultures. In Japan, for example, ending a life with honor by seppuku was considered a desirable death, whereas according to traditional Christian and Islamic cultures, suicide is viewed as a sin. Death is personified in many cultures, with such symbolic representations as the
Grim Reaper Death is frequently imagined as a personified force. In some mythologies, a character known as the Grim Reaper (usually depicted as a berobed skeleton wielding a scythe) causes the victim's death by coming to collect that person's soul. Other b ...
,
Azrael Azrael (; , 'God has helped'; ) is the angel of death in some Abrahamic religions, namely Islam, Christian popular culture and some traditions of Judaism. He is also referenced in Sikhism. Relative to similar concepts of such beings, Azrael ...
, the
Hindu Hindus (; ) are people who religiously adhere to Hinduism. Jeffery D. Long (2007), A Vision for Hinduism, IB Tauris, , pages 35–37 Historically, the term has also been used as a geographical, cultural, and later religious identifier for ...
god
Yama Yama (Devanagari: यम) or Yamarāja (यमराज), is a deity of death, dharma, the south direction, and the underworld who predominantly features in Hindu and Buddhist religion, belonging to an early stratum of Rigvedic Hindu deities. ...
and
Father Time Father Time is a personification of time. In recent centuries he is usually depicted as an elderly bearded man, sometimes with wings, dressed in a robe and carrying a scythe and an hourglass or other timekeeping device. As an image, "Father Ti ...
. In Brazil, a human death is counted officially when it is registered by existing family members at a cartório, a government-authorized registry. Before being able to file for an official death, the deceased must have been registered for an official birth at the cartório. Though a Public Registry Law guarantees all Brazilian citizens the right to register deaths, regardless of their financial means, of their family members (often children), the Brazilian government has not taken away the burden, the hidden costs and fees, of filing for a death. For many impoverished families, the indirect costs and burden of filing for a death lead to a more appealing, unofficial, local, cultural burial, which in turn raises the debate about inaccurate
mortality rates Mortality rate, or death rate, is a measure of the number of deaths (in general, or due to a specific cause) in a particular population, scaled to the size of that population, per unit of time. Mortality rate is typically expressed in units of de ...
. Talking about death and witnessing it is a difficult issue with most cultures. Western societies may like to treat the dead with the utmost material respect, with an official embalmer and associated rites. Eastern societies (like India) may be more open to accepting it as a ''fait accompli'', with a funeral procession of the dead body ending in an open-air burning-to-ashes of the same.


Consciousness

Much interest and debate surround the question of what happens to one's consciousness as one's body dies. The belief in the permanent loss of consciousness after death is often called ''
eternal oblivion Eternal oblivion (also referred to as non-existence or nothingness) is the philosophical or religious concept of one's consciousness forever ceasing upon death. Pamela Health and Jon Klimo write that this concept is mostly associated with religio ...
''. Belief that the
stream of consciousness In literary criticism, stream of consciousness is a narrative mode or method that attempts "to depict the multitudinous thoughts and feelings which pass through the mind" of a narrator. The term was coined by Daniel Oliver in 1840 in ''First L ...
is preserved after physical death is described by the term '' afterlife''. Neither are likely to ever be confirmed without the ponderer having to actually die.


In biology

After death, the remains of a former organism become part of the biogeochemical cycle, during which animals may be consumed by a
predator Predation is a biological interaction where one organism, the predator, kills and eats another organism, its prey. It is one of a family of common feeding behaviours that includes parasitism and micropredation (which usually do not kill th ...
or a scavenger.
Organic material Organic matter, organic material, or natural organic matter refers to the large source of carbon-based compounds found within natural and engineered, terrestrial, and aquatic environments. It is matter composed of organic compounds that have c ...
may then be further decomposed by detritivores, organisms which recycle detritus, returning it to the environment for reuse in the
food chain A food chain is a linear network of links in a food web starting from producer organisms (such as grass or algae which produce their own food via photosynthesis) and ending at an apex predator species (like grizzly bears or killer whales), de ...
, where these chemicals may eventually end up being consumed and assimilated into the cells of an organism. Examples of detritivores include
earthworm An earthworm is a terrestrial invertebrate that belongs to the phylum Annelida. They exhibit a tube-within-a-tube body plan; they are externally segmented with corresponding internal segmentation; and they usually have setae on all segments. T ...
s,
woodlice A woodlouse (plural woodlice) is an isopod crustacean from the polyphyleticThe current consensus is that Oniscidea is actually triphyletic suborder Oniscidea within the order Isopoda. They get their name from often being found in old wood ...
and
dung beetle Dung beetles are beetles that feed on feces. Some species of dung beetles can bury dung 250 times their own mass in one night. Many dung beetles, known as ''rollers'', roll dung into round balls, which are used as a food source or breeding cha ...
s.
Microorganism A microorganism, or microbe,, ''mikros'', "small") and ''organism'' from the el, ὀργανισμός, ''organismós'', "organism"). It is usually written as a single word but is sometimes hyphenated (''micro-organism''), especially in olde ...
s also play a vital role, raising the temperature of the decomposing matter as they break it down into yet simpler molecules. Not all materials need to be fully decomposed.
Coal Coal is a combustible black or brownish-black sedimentary rock, formed as rock strata called coal seams. Coal is mostly carbon with variable amounts of other elements, chiefly hydrogen, sulfur, oxygen, and nitrogen. Coal is formed when ...
, a fossil fuel formed over vast tracts of time in swamp ecosystems, is one example.


Natural selection

Contemporary
evolutionary theory Evolution is change in the heritable characteristics of biological populations over successive generations. These characteristics are the expressions of genes, which are passed on from parent to offspring during reproduction. Variation ...
sees death as an important part of the process of
natural selection Natural selection is the differential survival and reproduction of individuals due to differences in phenotype. It is a key mechanism of evolution, the change in the heritable traits characteristic of a population over generations. Cha ...
. It is considered that organisms less
adapted In biology, adaptation has three related meanings. Firstly, it is the dynamic evolutionary process of natural selection that fits organisms to their environment, enhancing their evolutionary fitness. Secondly, it is a state reached by the po ...
to their environment are more likely to die having produced fewer offspring, thereby reducing their contribution to the gene pool. Their genes are thus eventually bred out of a population, leading at worst to
extinction Extinction is the termination of a kind of organism or of a group of kinds (taxon), usually a species. The moment of extinction is generally considered to be the death of the last individual of the species, although the capacity to breed and ...
and, more positively, making the process possible, referred to as speciation. Frequency of reproduction plays an equally important role in determining species survival: an organism that dies young but leaves numerous offspring displays, according to
Darwinian Darwinism is a theory of biological evolution developed by the English naturalist Charles Darwin (1809–1882) and others, stating that all species of organisms arise and develop through the natural selection of small, inherited variations that ...
criteria, much greater fitness than a long-lived organism leaving only one.


Extinction

Extinction is the cessation of existence of a species or group of
taxa In biology, a taxon (back-formation from ''taxonomy''; plural taxa) is a group of one or more populations of an organism or organisms seen by taxonomists to form a unit. Although neither is required, a taxon is usually known by a particular nam ...
, reducing
biodiversity Biodiversity or biological diversity is the variety and variability of life on Earth. Biodiversity is a measure of variation at the genetic (''genetic variability''), species (''species diversity''), and ecosystem (''ecosystem diversity'') l ...
. The moment of extinction is generally considered to be the death of the last individual of that species (although the capacity to breed and recover may have been lost before this point). Because a species' potential
range Range may refer to: Geography * Range (geographic), a chain of hills or mountains; a somewhat linear, complex mountainous or hilly area (cordillera, sierra) ** Mountain range, a group of mountains bordered by lowlands * Range, a term used to i ...
may be very large, determining this moment is difficult, and is usually done retrospectively. This difficulty leads to phenomena such as Lazarus taxa, where species presumed extinct abruptly "reappear" (typically in the
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 ...
record) after a period of apparent absence. New species arise through the process of speciation, an aspect of
evolution Evolution is change in the heritable characteristics of biological populations over successive generations. These characteristics are the expressions of genes, which are passed on from parent to offspring during reproduction. Variation ...
. New varieties of organisms arise and thrive when they are able to find and exploit an
ecological niche In ecology, a niche is the match of a species to a specific environmental condition. Three variants of ecological niche are described by It describes how an organism or population responds to the distribution of resources and competitors (for ...
– and species become extinct when they are no longer able to survive in changing conditions or against superior competition.


Evolution of aging and mortality

Inquiry into the evolution of aging aims to explain why so many living things and the vast majority of animals weaken and die with age (exceptions include '' Hydra'' and the jellyfish ''
Turritopsis dohrnii ''Turritopsis dohrnii'', also known as the immortal jellyfish, is a species of small, biologically immortal jellyfish found worldwide in temperate to tropic waters. It is one of the few known cases of animals capable of reverting completely to ...
'', which research shows to be biologically immortal). The evolutionary origin of senescence remains one of the fundamental puzzles of biology. Gerontology specializes in the science of human aging processes. Organisms showing only asexual reproduction (e.g.
bacteria Bacteria (; singular: bacterium) are ubiquitous, mostly free-living organisms often consisting of one Cell (biology), biological cell. They constitute a large domain (biology), domain of prokaryotic microorganisms. Typically a few micrometr ...
, some
protist A protist () is any eukaryotic organism (that is, an organism whose cells contain a cell nucleus) that is not an animal, plant, or fungus. While it is likely that protists share a common ancestor (the last eukaryotic common ancestor), the exc ...
s, like the euglenoids and many amoebozoans) and
unicellular A unicellular organism, also known as a single-celled organism, is an organism that consists of a single cell, unlike a multicellular organism that consists of multiple cells. Organisms fall into two general categories: prokaryotic organisms and ...
organisms with
sexual reproduction Sexual reproduction is a type of reproduction that involves a complex life cycle in which a gamete ( haploid reproductive cells, such as a sperm or egg cell) with a single set of chromosomes combines with another gamete to produce a zygote th ...
(
colonial Colonial or The Colonial may refer to: * Colonial, of, relating to, or characteristic of a colony or colony (biology) Architecture * American colonial architecture * French Colonial * Spanish Colonial architecture Automobiles * Colonial (1920 au ...
or not, like the volvocine algae ''
Pandorina ''Pandorina'' is a genus of green algae composed of 8, 16, or sometimes 32 Cell (biology), cells, held together at their bases to form a sack globular colony surrounded by mucilage. The cells are ovoid or slightly narrowed at one end to appear Ke ...
'' and '' Chlamydomonas'') are "immortal" at some extent, dying only due to external hazards, like being eaten or meeting with a fatal accident. In
multicellular A multicellular organism is an organism that consists of more than one cell, in contrast to unicellular organism. All species of animals, land plants and most fungi are multicellular, as are many algae, whereas a few organisms are partially un ...
organisms (and also in
multinucleate Multinucleate cells (also known as multinucleated or polynuclear cells) are eukaryotic cells that have more than one nucleus per cell, i.e., multiple nuclei share one common cytoplasm. Mitosis in multinucleate cells can occur either in a coordina ...
ciliates The ciliates are a group of alveolates characterized by the presence of hair-like organelles called cilia, which are identical in structure to eukaryotic flagella, but are in general shorter and present in much larger numbers, with a different ...
), with a Weismannist development, that is, with a division of labor between mortal somatic (body) cells and "immortal" germ (reproductive) cells, death becomes an essential part of life, at least for the somatic line. The ''
Volvox ''Volvox'' is a polyphyletic genus of chlorophyte green algae in the family Volvocaceae. It forms spherical colonies of up to 50,000 cells. They live in a variety of freshwater habitats, and were first reported by Antonie van Leeuwenhoek in 170 ...
'' algae are among the simplest organisms to exhibit that division of labor between two completely different cell types, and as a consequence include death of somatic line as a regular, genetically regulated part of its life history.


Religious views


Buddhism

In Buddhist doctrine and practice, death plays an important role. Awareness of death was what motivated
Prince Siddhartha Siddhartha Gautama, most commonly referred to as the Buddha, was a wandering ascetic and religious teacher who lived in South Asia during the 6th or 5th century BCE and founded Buddhism. According to Buddhist tradition, he was born in Lu ...
to strive to find the "deathless" and finally to attain enlightenment. In Buddhist doctrine, death functions as a reminder of the value of having been born as a human being. Being reborn as a human being is considered the only state in which one can attain enlightenment. Therefore, death helps remind oneself that one should not take life for granted. The belief in rebirth among Buddhists does not necessarily remove
death anxiety Death anxiety is anxiety caused by thoughts of one's own death, and is also referred to as thanatophobia (fear of death). Death anxiety differs from necrophobia, which is the fear of others who are dead or dying. Psychotherapist Robert Langs ...
, since all existence in the cycle of rebirth is considered filled with suffering, and being reborn many times does not necessarily mean that one progresses. Death is part of several key Buddhist tenets, such as the Four Noble Truths and
dependent origination A dependant is a person who relies on another as a primary source of income. A common-law spouse who is financially supported by their partner may also be included in this definition. In some jurisdictions, supporting a dependant may enabl ...
.


Christianity

While there are different sects of Christianity with different branches of belief; the overarching ideology on death grows from the knowledge of afterlife. Meaning after death the individual will undergo a separation from mortality to immortality; their soul leaves the body entering a realm of spirits. Following this separation of body and spirit (i.e. death)
resurrection Resurrection or anastasis is the concept of coming back to life after death. In a number of religions, a dying-and-rising god is a deity which dies and is resurrected. Reincarnation is a similar process hypothesized by other religions, whic ...
will occur. Representing the same transformation
Jesus Christ Jesus, likely from he, יֵשׁוּעַ, translit=Yēšūaʿ, label=Hebrew/Aramaic ( AD 30 or 33), also referred to as Jesus Christ or Jesus of Nazareth (among other names and titles), was a first-century Jewish preacher and religious ...
embodied after his body was placed in the tomb for three days. Like Him, each person's body will be resurrected reuniting the spirit and body in a perfect form. This process allows the individuals soul to withstand death and transform into life after death.


Hinduism

In Hindu texts, death is described as the individual eternal spiritual '' jiva-atma'' (soul or conscious self) exiting the current temporary material body. The soul exits this body when the body can no longer sustain the conscious self (life), which may be due to mental or physical reasons, or more accurately, the inability to act on one's ''
kama ''Kama'' (Sanskrit ) means "desire, wish, longing" in Hindu, Buddhist, Jain, and Sikh literature.Monier Williamsकाम, kāmaMonier-Williams Sanskrit English Dictionary, pp 271, see 3rd column Kama often connotes sensual pleasure, sexual ...
'' (material desires). During conception, the soul enters a compatible new body based on the remaining merits and demerits of one's ''
karma Karma (; sa, कर्म}, ; pi, kamma, italic=yes) in Sanskrit means an action, work, or deed, and its effect or consequences. In Indian religions, the term more specifically refers to a principle of cause and effect, often descriptivel ...
'' (good/bad material activities based on '' dharma'') and the state of one's mind (impressions or last thoughts) at the time of death. Usually the process of
reincarnation Reincarnation, also known as rebirth or transmigration, is the philosophical or religious concept that the non-physical essence of a living being begins a new life in a different physical form or body after biological death. Resurrection is ...
(soul's transmigration) makes one forget all memories of one's previous life. Because nothing really dies and the temporary material body is always changing, both in this life and the next, death means forgetfulness of one's previous experiences (previous material identity). Material existence is described as being full of miseries arising from birth, disease, old age, death, mind, weather, etc. To conquer '' samsara'' (the cycle of death and rebirth) and become eligible for one of the different types of ''
moksha ''Moksha'' (; sa, मोक्ष, '), also called ''vimoksha'', ''vimukti'' and ''mukti'', is a term in Hinduism, Buddhism, Jainism and Sikhism for various forms of emancipation, enlightenment, liberation, and release. In its soteriologic ...
'' (liberation), one has to first conquer ''
kama ''Kama'' (Sanskrit ) means "desire, wish, longing" in Hindu, Buddhist, Jain, and Sikh literature.Monier Williamsकाम, kāmaMonier-Williams Sanskrit English Dictionary, pp 271, see 3rd column Kama often connotes sensual pleasure, sexual ...
'' (material desires) and become self-realized. The human form of life is most suitable for this spiritual journey, especially with the help of ''
sadhu ''Sadhu'' ( sa, साधु, IAST: ' (male), ''sādhvī'' or ''sādhvīne'' (female)), also spelled ''saddhu'', is a religious ascetic, mendicant or any holy person in Hinduism, Buddhism, and Jainism who has renounced the worldly life. ...
'' (self-realized saintly persons), '' sastra'' (revealed spiritual scriptures), and ''
guru Guru ( sa, गुरु, IAST: ''guru;'' Pali'': garu'') is a Sanskrit term for a "mentor, guide, expert, or master" of certain knowledge or field. In pan-Indian traditions, a guru is more than a teacher: traditionally, the guru is a reverential ...
'' (self-realized spiritual masters), given all three are in agreement.


Islam

The Islamic view is that death is the separation of the soul from the body as well as the beginning of the afterlife. The afterlife or ''
akhirah al-Ākhirah ( ar, الآخرة, derived from ''Akhir'' which means last, ultimate, end or close) is an Arabic term for "the Hereafter". In Islamic eschatology, on the Day of Last Judgment, the natural or temporal world (''dunya'') will come to ...
'' is one of the six main beliefs in Islam. Rather than seeing death as the end of life, Muslims consider death as a continuation of life in another form. In Islam, the life on earth right now is a short, temporary life and a testing period for every soul. The true life begins with the Day of Judgement, when all people will be divided into two groups. The righteous believers will be welcomed to ''
janna Janna (Kannada : ಮಹಾಕವಿ ಜನ್ನ) was one of the well-known Kannada poets of the early 13th century who also served in the capacity of a minister and a builder of temples. He graced the court of Hoysala empire King Veera Ba ...
'' (heaven) and the disbelievers and evildoers will be punished in ''
jahannam In Islam, the place of punishment for unbelievers and other evildoers in the afterlife, or hell, is an "integral part of Islamic theology", Thomassen, "Islamic Hell", Numen, 56, 2009: p.401 and has "occupied an important place in the Muslim imagi ...
'' (hellfire). Muslims believe death to be wholly natural and predetermined by God. Only God knows the exact time of a person’s death.
The Quran The Quran (, ; Standard Arabic: , Quranic Arabic: , , 'the recitation'), also romanized Qur'an or Koran, is the central religious text of Islam, believed by Muslims to be a revelation from God. It is organized in 114 chapters (pl.: , sing. ...
emphasizes that death is inevitable, no matter how much people try to escape death, it will reach everyone. Life on earth is the one and only chance for people to prepare themselves for the life to come and choose to either believe or not believe in God, and death is the end of that learning opportunity.


Judaism

There are a variety of beliefs about the afterlife within Judaism, but none of them contradict the preference of life over death. This is partially because death puts a cessation to the possibility of fulfilling any commandments.


Language

The word "death" comes from
Old English Old English (, ), or Anglo-Saxon, is the earliest recorded form of the English language, spoken in England and southern and eastern Scotland in the early Middle Ages. It was brought to Great Britain by Anglo-Saxon settlers in the mid-5th c ...
''dēaþ'', which in turn comes from Proto-Germanic *''dauþuz'' (reconstructed by etymological analysis). This comes from the Proto-Indo-European stem *''dheu-'' meaning the "process, act, condition of
dying Dying is the final stage of life which will eventually lead to death. Diagnosing dying is a complex process of clinical decision-making, and most practice checklists facilitating this diagnosis are based on cancer diagnoses. Signs of dying ...
". The concept and symptoms of death, and varying degrees of delicacy used in discussion in public forums, have generated numerous scientific, legal, and socially acceptable terms or euphemisms. When a person has died, it is also said they have "passed away", "passed on", "expired", or "gone", among other socially accepted, religiously specific, slang, and irreverent terms. As a formal reference to a dead person, it has become common practice to use the
participle In linguistics, a participle () (from Latin ' a "sharing, partaking") is a nonfinite verb form that has some of the characteristics and functions of both verbs and adjectives. More narrowly, ''participle'' has been defined as "a word derived from ...
form of "decease", as in "the deceased"; another noun form is "
decedent Death is the irreversible cessation of all biological functions that sustain an organism. For organisms with a brain, death can also be defined as the irreversible cessation of functioning of the whole brain, including brainstem, and brain ...
". Bereft of life, the dead person is a "corpse", " cadaver", "body", "set of remains" or, when all flesh is gone, a " skeleton". The terms " carrion" and "carcass" are also used, usually for dead non-human animals. The ashes left after a
cremation Cremation is a method of final disposition of a dead body through burning. Cremation may serve as a funeral or post-funeral rite and as an alternative to burial. In some countries, including India and Nepal, cremation on an open-air pyre is ...
are lately called "cremains".


See also

*
Casualty (person) A casualty, as a term in military usage, is a person in military service, combatant or non-combatant, who becomes unavailable for duty due to any of several circumstances, including death, injury, illness, capture or desertion. In civilian u ...
*
Day of Judgment The Last Judgment, Final Judgment, Day of Reckoning, Day of Judgment, Judgment Day, Doomsday, Day of Resurrection or The Day of the Lord (; ar, یوم القيامة, translit=Yawm al-Qiyāmah or ar, یوم الدین, translit=Yawm ad-Dīn, ...
*
Day of the Dead The Day of the Dead ( es, Día de Muertos or ''Día de los Muertos'') is a holiday traditionally celebrated on November 1 and 2, though other days, such as October 31 or November 6, may be included depending on the locality. It is widely obser ...
* Deathbed *
Death drive In classical Freudian psychoanalytic theory, the death drive (german: Todestrieb) is the drive toward death and destruction, often expressed through behaviors such as aggression, repetition compulsion, and self-destructiveness.Eric Berne, '' ...
* Death row * Death trajectory *
Dying Dying is the final stage of life which will eventually lead to death. Diagnosing dying is a complex process of clinical decision-making, and most practice checklists facilitating this diagnosis are based on cancer diagnoses. Signs of dying ...
*
Dying declaration In the law of evidence, a dying declaration is testimony that would normally be barred as hearsay but may in common law nonetheless be admitted as evidence in criminal law trials because it constituted the last words of a dying person. The ratio ...
* End-of-life care *
Eschatology Eschatology (; ) concerns expectations of the end of the present age, human history, or of the world itself. The end of the world or end times is predicted by several world religions (both Abrahamic and non-Abrahamic), which teach that nega ...
*
Faked death A faked death, also called a staged death or pseudocide, is the act of an individual purposely deceiving other people into believing that the individual is dead, when the person is, in fact, still alive. People who commit pseudocide can do so by l ...
*
Karōshi , which can be translated into "overwork death", is a Japanese term relating to occupation-related sudden death. The most common medical causes of karoshi deaths are heart attacks and strokes due to stress and malnourishment or fasting. Menta ...
*
Last rites The last rites, also known as the Commendation of the Dying, are the last prayers and ministrations given to an individual of Christian faith, when possible, shortly before death. They may be administered to those awaiting execution, mortall ...
* List of deaths by year *
List of expressions related to death This is a list of words and phrases related to death in alphabetical order. While some of them are slang, others euphemize the unpleasantness of the subject, or are used in formal contexts. Some of the phrases may carry the meaning of 'kill', or si ...
* Memento mori *
Near-death experience A near-death experience (NDE) is a profound personal experience associated with death or impending death which researchers claim share similar characteristics. When positive, such experiences may encompass a variety of sensations including detac ...
*
Origin-of-death myth The origin of death is a theme in the myths of many cultures. Death is a universal feature of human life, so stories about its origin appear to be universal in human cultures. As such it is a form of cosmological myth (a type of myth that explains ...
* Spiritual death * Survivalism (life after death) *
Taboo on the dead The taboo on the dead includes the taboo against touching of the dead, those surrounding them and anything associated with the dead. Taboo against naming the dead A taboo against naming the dead is a kind of word taboo whereby the name of a recen ...
*
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 ...
*
Yama Yama (Devanagari: यम) or Yamarāja (यमराज), is a deity of death, dharma, the south direction, and the underworld who predominantly features in Hindu and Buddhist religion, belonging to an early stratum of Rigvedic Hindu deities. ...


References


Bibliography

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Further reading

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External links

* * * * * Interviews with people dying in hospices, and portraits of them before, and shortly after, death. * How the medical profession categorized causes of death. * A biologist explains life and death in different kinds of organisms, in relation to evolution.
"Death" (video; 10:18)
by
Timothy Ferris Timothy Ferris (born August 29, 1944) is an American science writer and the best-selling author of twelve books, including ''The Science of Liberty'' (2010) and ''Coming of Age in the Milky Way'' (1988), for which he was awarded the American ...
, producer of the
Voyager Golden Record The Voyager Golden Records are two phonograph records that were included aboard both Voyager spacecraft launched in 1977. The records contain sounds and images selected to portray the diversity of life and culture on Earth, and are intended for ...
for
NASA The National Aeronautics and Space Administration (NASA ) is an independent agencies of the United States government, independent agency of the US federal government responsible for the civil List of government space agencies, space program ...
. 2021 {{Authority control Senescence