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Death is the
irreversible Irreversible may refer to: * Irreversible process, in thermodynamics, a process that is not reversible *'' Irréversible'', a 2002 film * ''Irréversible'' (soundtrack), soundtrack to the film ''Irréversible'' * An album recorded by hip-hop artis ...
cessation of all biological functions that sustain a
living Living or The Living may refer to: Common meanings *Life, a condition that distinguishes organisms from inorganic objects and dead organisms ** Living species, one that is not extinct *Personal life, the course of an individual human's life * ...
organism In biology, an organism () is any life, living system that functions as an individual entity. All organisms are composed of cells (cell theory). Organisms are classified by taxonomy (biology), taxonomy into groups such as Multicellular o ...
. 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 eventually and inevitably occurs in all organisms. Some organisms, such as ''
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 ...
'', are biologically
immortal Immortality is the ability to live forever, or eternal life. Immortal or Immortality may also refer to: Film * ''The Immortals'' (1995 film), an American crime film * ''Immortality'', an alternate title for the 1998 British film ''The Wisdom of ...
, however they can still die from means other than
aging Ageing ( BE) or aging ( AE) is the process of becoming older. The term refers mainly to humans, many other animals, and fungi, whereas for example, bacteria, perennial plants and some simple animals are potentially biologically immortal. In ...
. Death is generally applied to whole organisms; the equivalent for individual components of an organism, such as
cells Cell most often refers to: * Cell (biology), the functional basic unit of life Cell may also refer to: Locations * Monastic cell, a small room, hut, or cave in which a religious recluse lives, alternatively the small precursor of a monastery w ...
or tissues, is
necrosis Necrosis () is a form of cell injury which results in the premature death of cells in living tissue by autolysis. Necrosis is caused by factors external to the cell or tissue, such as infection, or trauma which result in the unregulated dig ...
. Something that is not considered an organism, such as a
virus A virus is a wikt:submicroscopic, submicroscopic infectious agent that replicates only inside the living Cell (biology), cells of an organism. Viruses infect all life forms, from animals and plants to microorganisms, including bacteria and ...
, can be physically destroyed but is not said ''to die'', as a virus is not considered alive in the first place. As of the early 21st century, 56 million people die per year. The most common reason is
cardiovascular disease Cardiovascular disease (CVD) is a class of diseases that involve the heart or blood vessels. CVD includes coronary artery diseases (CAD) such as angina and myocardial infarction (commonly known as a heart attack). Other CVDs include stroke, ...
, which is a
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 ...
that affects the
heart The heart is a muscular organ found 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 diox ...
or
blood vessel Blood vessels are the structures of the circulatory system that transport blood throughout the human body. These vessels transport blood cells, nutrients, and oxygen to the tissues of the body. They also take waste and carbon dioxide away from ...
s. As of 2022, an estimated total of 109 billion humans have died, or roughly 93.8% of all humans to ever live. A substudy of
gerontology Gerontology ( ) is the study of the social, cultural, psychological, cognitive, and biological aspects of aging. The word was coined by Ilya Ilyich Mechnikov in 1903, from the Greek , ''geron'', "old man" and , ''-logia'', "study of". The fiel ...
known as
biogerontology Biogerontology is the sub-field of gerontology concerned with the biological aging process, its evolutionary origins, and potential means to intervene in the process. The term "biogerontology" was coined by S. Rattan, and came in regular use wit ...
seeks to eliminate death by natural aging in humans, often through the application of natural processes found in certain organisms. However, as humans do not have the means to apply this to themselves, they have to use other ways to reach the
maximum lifespan Maximum life span (or, for humans, maximum reported age at death) is a measure of the maximum amount of time one or more members of a population have been observed to survive between birth and death. The term can also denote an estimate of the max ...
for a human, often through
lifestyle Lifestyle often refers to: * Lifestyle (sociology), the way a person lives * ''Otium'', ancient Roman concept of a lifestyle * Style of life (german: Lebensstil, link=no), dealing with the dynamics of personality Lifestyle may also refer to: Bus ...
changes, such as calorie reduction,
dieting Dieting is the practice of eating food in a regulated way to decrease, maintain, or increase body weight, or to prevent and treat diseases such as diabetes and obesity. As weight loss depends on calorie intake, different kinds of calorie-reduc ...
, and exercise. The idea of
lifespan extension Life extension is the concept of extending the human lifespan, either modestly through improvements in medicine or dramatically by increasing the maximum lifespan beyond its generally-settled limit of 125 years. Several researchers in the area ...
is considered and studied as a way for people to live longer. Determining when a person has definitively died has proven difficult. Initially, death was defined as occurring when breathing and the heartbeat ceased, a status still known as
clinical death Clinical death is the medical term for cessation of blood circulation and breathing, the two criteria necessary to sustain the lives of human beings and of many other organisms. It occurs when the heart stops beating in a regular rhythm, a conditi ...
. However, the development of
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) meant that such a state was no longer strictly irreversible. Brain death was then considered a better option, but several definitions exist for this. Some people believe that all brain functions must cease. Others believe that even if the
brainstem The brainstem (or brain stem) is the posterior stalk-like part of the brain that connects the cerebrum with the spinal cord. In the human brain the brainstem is composed of the midbrain, the pons, and the medulla oblongata. The midbrain is ...
is still alive, the personality and identity are irretrievably lost, so therefore, the person should be considered entirely dead. Brain death is sometimes used as a legal definition of death. For all organisms with a brain, death can instead be focused on this organ. The
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 ...
is usually considered important and an
autopsy An autopsy (post-mortem examination, obduction, necropsy, or autopsia cadaverum) is a surgical procedure that consists of a thorough examination of a corpse by dissection to determine the cause, mode, and manner of death or to evaluate any dis ...
can be done. There are many causes, from
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 to diseases. Many cultures and religions have a concept of an afterlife that may hold the idea of
judgment 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. There are also different customs for honoring the body, such as a funeral,
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 ...
, or
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 ...
. After a death, an obituary may be posted in a newspaper, and the "survived by" kin and friends usually go through the
grieving process The five stages of grief model (or the Kübler-Ross model) is popularly known as a model that describes a series of emotions experienced by people who are grieving: denial, anger, bargaining, depression and acceptance. In actuality, the Kübler-Ro ...
.


Diagnosis


Problems of definition

The concept of death is the 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.


Defining life to define death

One of the challenges in defining death is in distinguishing it from life. As a point in time, death seems to refer to the moment when 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. 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 ''d ...
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 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.


Definition of death by heartbeat and breath

Historically, attempts to define the exact moment of a human's death have been subjective or imprecise. Death was defined as the cessation of
heart The heart is a muscular organ found 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 diox ...
beat (cardiac arrest) and
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 spont ...
and prompt
defibrillation Defibrillation is a treatment for life-threatening cardiac arrhythmias, specifically ventricular fibrillation (V-Fib) and non-perfusing ventricular tachycardia (V-Tach). A defibrillator delivers a dose of electric current (often called a ''coun ...
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 (CDD). Proponents of the CDD believe 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 is applied fast enough, the person could be revived. Thus, the arguments for and against the CDD boil down to defining the actual words "permanent" and "irreversible," which further complicates the challenge of defining death. Furthermore, events 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 Life support comprises the treatments and techniques performed in an emergency in order to support life after the failure of one or more vital organs. Healthcare providers and emergency medical technicians are generally certified to perform basic ...
devices,
organ transplants Organ transplantation is a medical procedure in which an organ (anatomy), organ is removed from one body and placed in the body of a recipient, to replace a damaged or missing organ. The donor and recipient may be at the same location, or organ ...
, 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 ei ...
s.


Brain death

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 Perception, sensory activity, reduced muscle activity and reduced interactions with surroundings. It is distinguished from wakefuln ...
stages, and especially a coma. In the case of sleep, Electroencephalogram ( EEGs) are used to tell the difference. The category of "brain death" is seen as problematic by some scholars. For instance, Dr. Franklin Miller, a 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 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 in a vegetative state or coma, in that the former situation describes a state that is beyond recovery. 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 be ...
,
hypoxia Hypoxia means a lower than normal level of oxygen, and may refer to: Reduced or insufficient oxygen * Hypoxia (environmental), abnormally low oxygen content of the specific environment * Hypoxia (medical), abnormally low level of oxygen in the tis ...
, 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 h ...
can suppress or even stop brain activity temporarily; because of this, hospitals have protocols for determining brain death involving EEGs at widely separated intervals under defined conditions.


Neocortical brain death

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, s ...
of the brain is necessary for consciousness sometimes argue that only electrical activity should be considered when defining death. Eventually, the criterion for death may be the permanent and irreversible loss of
cognitive Cognition refers to "the mental action or process of acquiring knowledge and understanding through thought, experience, and the senses". It encompasses all aspects of intellectual functions and processes such as: perception, attention, thought ...
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% consisting o ...
. 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, mos ...
is then gone, given current and foreseeable medical technology. Even by whole-brain criteria, the determination of brain death can be complicated.


Total brain death

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. One example is the
Uniform Determination Of Death Act The Uniform Determination of Death Act (UDDA) is a model state law that was approved for the United States in 1981 by the National Conference of Commissioners on Uniform State Laws, in cooperation with the American Medical Association, the Ame ...
in the United States. In the past, the 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 was 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 to proceed with organ donation.


Problems in medical practice

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 the criteria that became the medical standard for diagnosing neurologic death. At that time, three clinical features had to be satisfied to determine "irreversible cessation" of the total brain, including coma with clear etiology, cessation of breathing, and lack of brainstem reflexes. These criteria were updated again, most recently in 2010, but substantial discrepancies remain across hospitals and medical specialties.


Donations

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 res ...
, 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 the 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 that the rule is legitimate in protecting organ donors while also countering 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 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 pe ...
(no
breathing 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 ...
) *
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 ...
) * 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 vie ...
, 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 ...
, 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 jurisdictions. Most countries follow the whole-brain death criteria, where all functions of the brain must have completely ceased. However, in other jurisdictions, some follow the brainstem version of brain death. Afterward, 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.


Misdiagnosis

There are many anecdotal references to people being declared dead by physicians and then "coming back to life," sometimes days later in their 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 The rectum is the final straight portion of the large intestine in humans and some other mammals, and the gut in others. The adult human rectum is about long, and begins at the rectosigmoid junction (the end of the sigmoid colon) at the l ...
. 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 some estimates peg the figure to be closer to 800. In cases of
electric shock Electrical injury is a physiological reaction caused by electric current passing through the body. The injury depends on the density of the current, tissue resistance and duration of contact. Very small currents may be imperceptible or produce a ...
,
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
nerve A nerve is an enclosed, cable-like bundle of nerve fibers (called axons) in the peripheral nervous system. A nerve transmits electrical impulses. It is the basic unit of the peripheral nervous system. A nerve provides a common pathway for the ...
s 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 An emergency department (ED), also known as an accident and emergency department (A&E), emergency room (ER), emergency ward (EW) or casualty department, is a medical treatment facility specializing in emergency medicine, the acute care of pa ...
. This "diving response," in which
metabolic activity Metabolism (, from el, μεταβολή ''metabolē'', "change") is the set of life-sustaining chemical reactions in organisms. The three main functions of metabolism are: the conversion of the energy in food to energy available to run cell ...
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 op ...
. As medical technologies advance, ideas about when death occurs may have to be reevaluated 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 ...
.


Causes

The leading cause of human death in
developing countries A developing country is a sovereign state with a lesser developed Industrial sector, industrial base and a lower Human Development Index (HDI) relative to other countries. However, this definition is not universally agreed upon. There is al ...
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 d ...
. 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 infrastr ...
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 ...
(
heart disease Cardiovascular disease (CVD) is a class of diseases that involve the heart or blood vessels. CVD includes coronary artery diseases (CAD) such as angina and myocardial infarction (commonly known as a heart attack). Other CVDs include stroke, ...
and stroke), cancer, 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 Ageing ( BE) or aging ( AE) is the process of becoming older. The term refers mainly to humans, many other animals, and fungi, whereas for example, bacteria, perennial plants and some simple animals are potentially biologically immortal. In ...
. 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 An aging-associated disease (commonly termed age-related disease, ARD) is a disease that is most often seen with increasing frequency with increasing senescence. They are essentially complications of senescence, distinguished from the aging proc ...
. These conditions cause loss of
homeostasis In biology, homeostasis (British English, British also homoeostasis) Help:IPA/English, (/hɒmɪə(ʊ)ˈsteɪsɪs/) is the state of steady internal, physics, physical, and chemistry, chemical conditions maintained by organism, living systems. Thi ...
, leading to cardiac arrest, 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 we ...
and nutrient supply, causing irreversible deterioration of the brain 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. 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 Health technology is defined by the World Health Organization as the "application of organized knowledge and skills in the form of devices, medicines, vaccines, procedures, and systems developed to solve a health problem and improve quality of li ...
make death from
infectious diseases 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 d ...
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 infrastr ...
. 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, in w ...
, a bacterial disease that killed 1.8 million 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 deat ...
causes about 400–900 million cases of fever and 1–3M deaths annually. The AIDS death toll in Africa may reach 90–100 million 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 ...
, the United Nations 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 62 million people died from all causes and of those deaths, more than 36 million died of hunger or diseases due to deficiencies in
micronutrient Micronutrients are essential dietary elements required by organisms in varying quantities throughout life to orchestrate a range of physiological functions to maintain health. Micronutrient requirements differ between organisms; for example, huma ...
s. Tobacco smoking killed 100 million people worldwide in the 20th century and could kill 1 billion people worldwide 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 o ...
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 word " longevity" is sometimes used as a synonym for "life expectancy" in demography. However, the term ''longevity'' is sometimes meant to refer only to especially long-lived members of a population, whereas ''life expectancy'' is always d ...
. The evolutionary cause of aging is, at best, only 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 decreases the adaptability of an organism and proposed to describe 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 adaptability is a finite supply presented at birth. Later, Goldstone proposed the concept of 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 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 as the leading cause of human injury deaths in the U.S., followed by poisoning, falls, and murder. Accidents and disasters, from
nuclear disasters A nuclear and radiation accident is defined by the International Atomic Energy Agency (IAEA) as "an event that has led to significant consequences to people, the environment or the facility. Examples include lethal effects to individuals, lar ...
to structural collapses, also claim lives. One of the deadliest incidents of all time is the Failure of the
1975 Banqiao Dam Failure The 1975 Banqiao Dam failure (simplified Chinese: 河南“75·8”水库溃坝; traditional Chinese: 河南「75·8」水庫潰壩) was the collapse of the Banqiao Dam and 61 other dams in Henan, China, under the influence of Typhoon Nina in ...
, with varying estimates, up to 240,000 dead. Other incidents with high death tolls are the
Wanggongchang explosion The Wanggongchang Explosion ( zh, t=王恭廠大爆炸), also known as the Great Tianqi Explosion ( zh, t=天啟大爆炸, labels=no), Wanggongchang Calamity ( zh, t=王恭廠之變, labels=no) or Beijing Explosive Incident in the late Ming dy ...
(when a gunpowder factory ended up with 20,000 deaths), a collapse of a wall of
Circus Maximus The Circus Maximus ( Latin for "largest circus"; Italian: ''Circo Massimo'') is an ancient Roman chariot-racing stadium and mass entertainment venue in Rome, Italy. In the valley between the Aventine and Palatine hills, it was the first and ...
that killed 13,000 people, and the
Chernobyl disaster The Chernobyl disaster was a nuclear accident that occurred on 26 April 1986 at the No. 4 nuclear reactor, reactor in the Chernobyl Nuclear Power Plant, near the city of Pripyat in the north of the Ukrainian Soviet Socialist Republic, Ukrainia ...
that killed between 95 and 4,000 people. Natural disasters kill around 45,000 people annually, although this number can vary to millions to thousands on a per-decade basis. Some of the deadliest natural disasters are the
1931 China floods The 1931 China floods, or the 1931 Yangtze–Huai River floods, occurred from June to August 1931 in China, hitting major cities such as Wuhan, Nanjing and beyond, which eventually culminated into a dike breach along Lake Gaoyou on 25 August ...
, which killed an estimated 4 million people, although estimates widely vary; the
1887 Yellow River flood The 1887 Yellow River flood in Qing China began in September 1887 and killed at least 930,000 people.1970 Bhola cyclone The 1970 Bhola cyclone (Also known as the Great Cyclone of 1970) was a devastating tropical cyclone that struck East Pakistan (present-day Bangladesh) and India's West Bengal on November 11, 1970. It remains the deadliest tropical cyclone ever re ...
, which killed as many as 500,000 people in Pakistan. If naturally occurring
famine A famine is a widespread scarcity of food, caused by several factors including war, natural disasters, crop failure, population imbalance, widespread poverty, an economic catastrophe or government policies. This phenomenon is usually accom ...
s are considered natural disasters, the
Chinese famine of 1906–1907 The Chinese famine of 1906–1907 struck the middle and lower course of Huai River in Qing Dynasty from Autumn 1906 to Spring 1907, administratively in northern Anhui and northern Jiangsu provinces. This Chinese famine was directly caused by ...
, which killed 15–20 million people, can be considered the deadliest natural disaster in recorded history. In animals,
predation Predation is a biological interaction In ecology, a biological interaction is the effect that a pair of organisms living together in a community have on each other. They can be either of the same species (intraspecific interactions), or o ...
can be a common cause of death. Livestock have a 6% death rate from predation. However, younger animals are more susceptible to predation. For example, 50% of young foxes die to
birds Birds are a group of warm-blooded vertebrates constituting the class Aves (), characterised by feathers, toothless beaked jaws, the laying of hard-shelled eggs, a high metabolic rate, a four-chambered heart, and a strong yet lightweig ...
,
bobcat The bobcat (''Lynx rufus''), also known as the red lynx, is a medium-sized cat native to North America. It ranges from southern Canada through most of the contiguous United States to Oaxaca in Mexico. It is listed as Least Concern on the IU ...
s,
coyote The coyote (''Canis latrans'') is a species of canine native to North America. It is smaller than its close relative, the wolf, and slightly smaller than the closely related eastern wolf and red wolf. It fills much of the same ecological ni ...
s, and other foxes as well. Young bear cubs in the
Yellowstone National Park Yellowstone National Park is an American national park located in the western United States, largely in the northwest corner of Wyoming Wyoming () is a state in the Mountain West subregion of the Western United States. It is border ...
only have a 40% chance to survive to adulthood from other bears and predators.


Autopsy

An
autopsy An autopsy (post-mortem examination, obduction, necropsy, or autopsia cadaverum) is a surgical procedure that consists of a thorough examination of a corpse by dissection to determine the cause, mode, and manner of death or to evaluate any dis ...
, 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. S ...
to determine the cause and manner of a person's death and to evaluate any disease or injury that may be present. It is usually performed by a specialized
medical doctor A physician (American English), medical practitioner (Commonwealth English), medical doctor, or simply doctor, is a health professional who practices medicine, which is concerned with promoting, maintaining or restoring health through the ...
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 A person's next of kin (NOK) are that person's closest living blood relatives. Some countries, such as the United States, have a legal definition of "next of kin". In other countries, such as the United Kingdom, "next of kin" may have no legal d ...
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. 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.


Death before birth

Death before birth can happen in several ways:
stillbirth Stillbirth is typically defined as fetal death at or after 20 or 28 weeks of pregnancy, depending on the source. It results in a baby born without signs of life. A stillbirth can result in the feeling of guilt or grief in the mother. The ter ...
, when the
fetus A fetus or foetus (; plural fetuses, feti, foetuses, or foeti) is the unborn offspring that develops from an animal embryo. Following embryonic development the fetal stage of development takes place. In human prenatal development, fetal develo ...
dies before or during the delivery process;
miscarriage Miscarriage, also known in medical terms as a spontaneous abortion and pregnancy loss, is the death of an embryo or fetus before it is able to survive independently. Miscarriage before 6 weeks of gestation is defined by ESHRE as biochemical ...
, when the embryo dies before independent survival; and abortion, the artificial termination of the pregnancy. Stillbirth and miscarriage can happen for various reasons, while abortion is carried out purposely.


Stillbirth

Stillbirth can happen right before or after the delivery of a fetus. It can result from defects of the fetus or
risk factor In epidemiology, a risk factor or determinant is a variable associated with an increased risk of disease or infection. Due to a lack of harmonization across disciplines, determinant, in its more widely accepted scientific meaning, is often us ...
s present in the mother. Reductions of these factors,
caesarean section Caesarean section, also known as C-section or caesarean delivery, is the surgical procedure by which one or more babies are delivered through an incision in the mother's abdomen, often performed because vaginal delivery would put the baby or ...
s when risks are present, and early detection of birth defects have lowered the rate of stillbirth. However, 1% of births in the United States end in a stillbirth.


Miscarriage

A miscarriage is defined by the
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 o ...
as, "The expulsion or extraction from its mother of an embryo or fetus weighing 500g or less." Miscarriage is one of the most frequent problems in pregnancy, and is reported in around 12–15% of all clinical pregnancies; however, by including pregnancy losses during
menstruation Menstruation (also known as a period, among other colloquial terms) is the regular discharge of blood and mucosal tissue from the inner lining of the uterus through the vagina. The menstrual cycle is characterized by the rise and fall of ...
, it could be up to 17–22% of all pregnancies. There are many risk-factors involved in miscarriage; consumption of
caffeine Caffeine is a central nervous system (CNS) stimulant of the methylxanthine class. It is mainly used recreationally as a cognitive enhancer, increasing alertness and attentional performance. Caffeine acts by blocking binding of adenosine t ...
, tobacco,
alcohol Alcohol most commonly refers to: * Alcohol (chemistry), an organic compound in which a hydroxyl group is bound to a carbon atom * Alcohol (drug), an intoxicant found in alcoholic drinks Alcohol may also refer to: Chemicals * Ethanol, one of sev ...
, drugs, having a previous miscarriage, and the use of abortion can increase the chances of having a miscarriage.


Abortion

An abortion may be performed for many reasons, such as
pregnancy from rape Pregnancy is a potential result of rape. It has been studied in the context of war, particularly as a tool for genocide, as well as other unrelated contexts, such as rape by a stranger, statutory rape, incest, and underage pregnancy. The curr ...
, financial constraints of having a child,
teenage pregnancy Teenage pregnancy, also known as adolescent pregnancy, is pregnancy in a female adolescent or young adult under the age of 20. This includes those who are legally considered adults in their country. The WHO defines adolescence as the period bet ...
, and the lack of support from a
significant other The term significant other (SO) has different uses in psychology and in colloquial language. Colloquially, "significant other" is used as a gender-neutral term for a person's partner in an intimate relationship without disclosing or presuming ...
. There are two forms of abortion: a
medical abortion A medical abortion, also known as medication abortion, occurs when drugs (medication) are used to bring about an abortion. Medical abortions are an alternative to surgical abortions such as vacuum aspiration or dilation and curettage. Medic ...
and an in-clinic abortion or sometimes referred to as a surgical abortion. A medical abortion involves taking a pill that will terminate the pregnancy no more than 11 weeks past the last
period Period may refer to: Common uses * Era, a length or span of time * Full stop (or period), a punctuation mark Arts, entertainment, and media * Period (music), a concept in musical composition * Periodic sentence (or rhetorical period), a concept ...
, and an in-clinic abortion involves a medical procedure using suction to empty the uterus; this is possible after 12 weeks, but it may be more difficult to find an operating doctor who will go through with the procedure.


Senescence

Senescence refers to a scenario when a living being can survive all calamities but eventually dies due to causes relating to old age. Conversely, premature death can refer to a death that occurs before old age arrives, for example, human death before a person reaches the age of 75. Animal and plant cells normally reproduce and function during the whole period of natural existence, but the aging process derives from the deterioration of cellular activity and the ruination of regular functioning. The 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 daily relates to senescence, while around the world, it accounts for two-thirds of 150,000 deaths that take place daily. Almost all animals who survive external hazards to their biological functioning eventually die from
biological aging Senescence () or biological aging is the gradual deterioration of functional characteristics in living organisms. The word ''senescence'' can refer to either cellular senescence or to senescence of the whole organism. Organismal senescence invo ...
, 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 declin ...
, even exhibiting
biological immortality Biological immortality (sometimes referred to as bio-indefinite mortality) is a state in which the rate of mortality from senescence is stable or decreasing, thus decoupling it from chronological age. Various unicellular and multicellular species ...
. 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 (biology), 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-li ...
. Unnatural causes of death include suicide and
predation Predation is a biological interaction In ecology, a biological interaction is the effect that a pair of organisms living together in a community have on each other. They can be either of the same species (intraspecific interactions), or o ...
. Of 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 Physiology (; ) is the scientific study of functions and mechanisms in a living system. As a sub-discipline of biology, physiology focuses on how organisms, organ systems, individual organs, cells, and biomolecules carry out the chemica ...
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 Clinical death is the medical term for cessation of blood circulation and breathing, the two criteria necessary to sustain the lives of human beings and of many other organisms. It occurs when the heart stops beating in a regular rhythm, a conditi ...
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 found 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 diox ...
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 of ...
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.


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 or reversing aging processes 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. Aging is the most common cause of death worldwide. Aging is seen as inevitable, so according to
Aubrey de Grey Aubrey David Nicholas Jasper de Grey (; born 20 April 1963) is an English author and biomedical gerontologist. He is the author of ''The Mitochondrial Free Radical Theory of Aging'' (1999) and co-author of ''Ending Aging'' (2007). He is known ...
little is spent on research into anti-aging therapies, a phenomenon known as
pro-aging trance Pro-aging trance, also known as pro-aging edifice, is a term coined by British author and biomedical gerontologist Aubrey de Grey to describe the broadly positive and fatalistic attitude toward aging in society. Overview According to de Grey, ...
. The 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 or
cardiovascular disease Cardiovascular disease (CVD) is a class of diseases that involve the heart or blood vessels. CVD includes coronary artery diseases (CAD) such as angina and myocardial infarction (commonly known as a heart attack). Other CVDs include stroke, ...
. Extension of 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 Smoking is a practice in which a substance is burned and the resulting smoke is typically breathed in to be tasted and absorbed into the bloodstream. Most commonly, the substance used is the dried leaves of the tobacco plant, which have bee ...
. Maximum lifespan is 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. A 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 be ...
. Theoretically, the extension of the maximum lifespan can be achieved by reducing the rate of aging damage, by periodic replacement of damaged tissues, 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 religious 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% said they would desire to have their aging process cured. Researchers of life extension can be known as "biomedical
gerontologist Gerontology ( ) is the study of the social, cultural, psychological, cognitive, and biological aspects of aging. The word was coined by Ilya Ilyich Mechnikov in 1903, from the Greek , ''geron'', "old man" and , ''-logia'', "study of". The fiel ...
s." They try to understand aging, and develop treatments to reverse aging processes, or at least slow them for the improvement of health and maintenance of youthfulness. Those who use life extension findings and apply them to themselves are called "life extensionists" or "longevists." The primary life extension strategy currently is to apply anti-aging methods to attempt to live long enough to benefit from a cure for aging.


Cryonics

Cryonics (from Greek κρύος 'kryos-' meaning 'icy cold') is the low-temperature preservation of animals, including humans, who cannot be sustained by contemporary medicine, with the hope that healing and
resuscitation Resuscitation is the process of correcting physiological disorders (such as lack of breathing or heartbeat) in an acutely ill patient. It is an important part of intensive care medicine, anesthesiology, trauma surgery and emergency medicine. ...
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 coo ...
of people and other 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 regard cryonics with skepticism.


Location

Around 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 or client, instead of the patient visiting the doctor's clinic or hospital. In some locations, families used to pay ...
s. By the mid-20th century, half of all Americans died in a hospital. By the start of the 21st century, only about 20 to 25% of people in developed countries died outside of a medical institution. The shift 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 betwe ...
. To varying degrees people inherently fear death, both the process and the eventuality; it is hard wired and part of the 'survival instinct' of all animals. Discussing, thinking about, or planning for their 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.
Mortality salience Mortality salience is the awareness by individuals that their death is inevitable. The term derives from terror management theory, which proposes that mortality salience causes existential anxiety that may be buffered by an individual's cultur ...
is the awareness that death is inevitable. However,
self-esteem Self-esteem is confidence in one's own worth or abilities. Self-esteem encompasses beliefs about oneself (for example, "I am loved", "I am worthy") as well as emotional states, such as triumph, despair, pride, and shame. Smith and Mackie (2007) d ...
and culture are ways to reduce the
anxiety Anxiety is an emotion which is characterized by an unpleasant state of inner turmoil Turmoil may refer to: * ''Turmoil'' (1984 video game), a 1984 video game released by Bug-Byte * ''Turmoil'' (2016 video game), a 2016 indie oil tycoon video ...
this effect can cause. The awareness of someone's own death can cause a deepened bond in their
in-group In sociology and social psychology, an in-group is a social group to which a person psychologically identifies as being a member. By contrast, an out-group is a social group with which an individual does not identify. People may for example ide ...
as a
defense mechanism In psychoanalytic theory, a defence mechanism (American English: defense mechanism), is an unconscious psychological operation that functions to protect a person from anxiety-producing thoughts and feelings related to internal conflicts and o ...
. This can also cause the person to become very judging. In a study, two groups were formed; one group was asked to reflect upon their mortality, the other was not, afterwards, the groups were told to set a
bond Bond or bonds may refer to: Common meanings * Bond (finance), a type of debt security * Bail bond, a commercial third-party guarantor of surety bonds in the United States * Chemical bond, the attraction of atoms, ions or molecules to form chemica ...
for a prostitute. The group that did not reflect on death had an average of $50, the group who was reminded about their death had an average of $455. Different people have different responses to the idea of their 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, Im ...
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 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 mortality has, for millennia, been a concern of the world's
religious traditions Religion is usually defined as a social-cultural system of designated behaviors and practices, morals, beliefs, worldviews, texts, sanctified places, prophecies, ethics, or organizations, that generally relates humanity to supernatural, transc ...
and
philosophical inquiry ''Philosophical Inquiry'' is a peer-reviewed academic journal that publishes articles, reviews, and critical notes in all areas of philosophy. The journal aims to facilitate international communication of philosophical thought, and it does this b ...
. Including 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 religion Religion is usually defined as a social- cultural system of designated behaviors and practices, morals, beliefs, worldviews, texts, sanctified places, prophecies, ethics, or organiza ...
),
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 Indian religions, sometimes also termed Dharmic religions or Indic religions, are the religions that originated in the Indian subcontinent. These religions, which include Hinduism, Jainism, Buddhism, and Sikhism,Adams, C. J."Classification of ...
), 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 religi ...
(associated with
Secular humanism Secular humanism is a philosophy, belief system or life stance that embraces human reason, secular ethics, and philosophical naturalism while specifically rejecting religious dogma, supernaturalism, and superstition as the basis of morality ...
). 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 honoring 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 Rest in peace (RIP), a phrase from the Latin (), is sometimes used in traditional Christian services and prayers, such as in the Catholic, Lutheran, Anglican, and Methodist denominations, to wish the soul of a decedent eternal rest and 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 ...
, ''requiescat in pace'') or its
initialism An acronym is a word or name formed from the initial components of a longer name or phrase. Acronyms are usually formed from the initial letters of words, as in ''NATO'' (''North Atlantic Treaty Organization''), but sometimes use syllables, as ...
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, ...
does, in general, begin with the
last offices The last offices, or laying out, is the procedures performed, usually by a nurse, to the body of a dead person shortly after death has been confirmed. They can vary between hospitals and between cultures. Name The word "offices" is related to the o ...
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 ...
. 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 people, ...
, 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), ...
. Some parts of death in culture are legally based, having laws for when death occurs, such as the receiving of a death certificate, the settlement of the deceased
estate Estate or The Estate may refer to: Law * Estate (law), a term in common law for a person's property, entitlements and obligations * Estates of the realm, a broad social category in the histories of certain countries. ** The Estates, representat ...
, 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. Offici ...
and, in some countries,
inheritance tax An inheritance tax is a tax paid by a person who inherits money or property of a person who has died, whereas an estate tax is a levy on the estate (money and property) of a person who has died. International tax law distinguishes between an e ...
ation. Capital punishment 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,
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 Military justice (also military law) is the legal system (bodies of law and procedure) that governs the conduct of the active-duty personnel of the armed forces of a country. In some nation-states, civil law and military law are distinct bod ...
. 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 leg ...
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 ''so ...
, 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 i ...
, the formal renunciation of one's religion. In many
retentionist Capital punishment, also known as the death penalty, is a state-sanctioned practice of killing a person as a punishment for a crime. Historically, capital punishment has been used in almost every part of the world. Currently, the large majorit ...
countries, drug trafficking is also a capital offense. In China,
human trafficking Human trafficking is the trade of humans for the purpose of forced labour, sexual slavery, or commercial sexual exploitation for the trafficker or others. This may encompass providing a spouse in the context of forced marriage, or the extr ...
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 Desertion is the abandonment of a military duty or post without permission (a pass, liberty or leave) and is done with the intention of not returning. This contrasts with unauthorized absence (UA) or absence without leave (AWOL ), whic ...
,
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 order ...
, and mutiny. Mutiny is punishable by death in the United States. Death in warfare and
suicide attack A suicide attack is any violent attack, usually entailing the attacker detonating an explosive, where the attacker has accepted their own death as a direct result of the attacking method used. Suicide attacks have occurred throughout history ...
s 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, ...
,'' which translates to "It is sweet and proper to die for one's country", is a concept that dates to antiquity. Additionally, grieving relatives of dead soldiers and
death notification A death notification is the delivery of the news of a death to another person. It describes the moment a person receives the news of someone's death. There are many roles that contribute to the death notification process. The ''notifier'' is th ...
are embedded in many cultures. Recently in the
Western world The Western world, also known as the West, primarily refers to the various nations and states in the regions of Europe, North America, and Oceania.
—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 commerc ...
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 to ...
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 World War II by country, vast majority of the world's countries—including all of the great power ...
, and suicide missions in a host of other conflicts in history—death for a cause by way of suicide attack, including
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 external ...
, have had significant cultural impacts. Suicide, in general, and particularly
euthanasia Euthanasia (from el, εὐθανασία 'good death': εὖ, ''eu'' 'well, good' + θάνατος, ''thanatos'' 'death') is the practice of intentionally ending life to eliminate pain and suffering. Different countries have different eut ...
, 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 , sometimes referred to as hara-kiri (, , a native Japanese kun reading), is a form of Japanese ritual suicide by disembowelment. It was originally reserved for samurai in their code of honour but was also practised by other Japanese peop ...
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 Judaism ( he, ''Yahăḏūṯ'') is an Abrahamic, monotheistic, and ethnic rel ...
, the Hindu 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 ...
. In the west, the Grim Reaper, or figures similar to it, is the most popular depiction of death in western cultures. In Brazil, 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, and 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 in 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.


Origins of death

The
origin of death 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 ...
is a theme or myth of how death came to be. It is present in nearly all cultures across the world, as death is a universal happening. This makes it an
origin myth An origin myth is a myth that describes the origin of some feature of the natural or social world. One type of origin myth is the creation or cosmogonic myth, a story that describes the creation of the world. However, many cultures have stor ...
, a myth that describes how a feature of the natural or social world appeared. There can be some similarities between myths and cultures. In North American mythology, the theme of a man who wants to be immortal and a man who wants to die can be seen across many
Indigenous people Indigenous peoples are culturally distinct ethnic groups whose members are directly descended from the earliest known inhabitants of a particular geographic region and, to some extent, maintain the language and culture of those original people ...
. In Christianity, death is the result of the
fall of man The fall of man, the fall of Adam, or simply the Fall, is a term used in Christianity to describe the transition of the first man and woman from a state of innocent obedience to God to a state of guilty disobedience. * * * * The doctrine of the ...
after eating the fruit from the
tree of the knowledge of good and evil In Judaism and Christianity, the tree of the knowledge of good and evil ( he, עֵץ הַדַּעַת טוֹב וָרָע, ʿêṣ had-daʿaṯ ṭōḇ wā-rāʿ, label=Tiberian Hebrew, ) is one of two specific trees in the story of the Garden ...
. In
Greek mythology A major branch of classical mythology, Greek mythology is the body of myths originally told by the ancient Greeks, and a genre of Ancient Greek folklore. These stories concern the origin and nature of the world, the lives and activities of ...
, the opening of
Pandora's box Pandora's box is an artifact in Greek mythology connected with the myth of Pandora in Hesiod's c. 700 B.C. poem '' Works and Days''. Hesiod reported that curiosity led her to open a container left in the care of her husband, thus releasing phy ...
releases death upon the world.


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 religi ...
''. The 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 is likely to be confirmed without the ponderer having to die. Near-death experiences are the closest thing people have to an afterlife that we know. Some people who have had
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 ...
s (NDEs) report that they have seen the afterlife while they were dead. Seeing a being of light and talking with it, life flashing before the eyes, and the confirmation of cultural beliefs of the afterlife are all themes that happen during the moments they are dead.


In biology

After death, the remains of a former organism become part of the
biogeochemical cycle A biogeochemical cycle (or more generally a cycle of matter) is the pathway by which a chemical substance cycles (is turned over or moves through) the biotic and the abiotic compartments of Earth. The biotic compartment is the biosphere and ...
, 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 ...
or a
scavenger Scavengers are animals that consume dead organisms that have died from causes other than predation or have been killed by other predators. While scavenging generally refers to carnivores feeding on carrion, it is also a herbivorous feeding b ...
.
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
detritivore Detritivores (also known as detrivores, detritophages, detritus feeders, or detritus eaters) are heterotrophs that obtain nutrients by consuming detritus (decomposing plant and animal parts as well as feces). There are many kinds of invertebrate ...
s, organisms that recycle
detritus In biology, detritus () is dead particulate organic material, as distinguished from dissolved organic material. Detritus typically includes the bodies or fragments of bodies of dead organisms, and fecal material. Detritus typically hosts commu ...
, 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), d ...
, 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. ...
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
millipede Millipedes are a group of arthropods that are characterised by having two pairs of jointed legs on most body segments; they are known scientifically as the class Diplopoda, the name derived from this feature. Each double-legged segment is a re ...
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, a fossil fuel formed over vast tracts of time in swamp ecosystems, is one example.


Natural selection

The 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 te ...
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 The gene pool is the set of all genes, or genetic information, in any population, usually of a particular species. Description A large gene pool indicates extensive genetic diversity, which is associated with robust populations that can surv ...
. 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, more positively, making the process possible, referred to as
speciation Speciation is the evolutionary process by which populations evolve to become distinct species. The biologist Orator F. Cook coined the term in 1906 for cladogenesis, the splitting of lineages, as opposed to anagenesis, phyletic evolution withi ...
. Frequency of
reproduction Reproduction (or procreation or breeding) is the biological process by which new individual organisms – " offspring" – are produced from their "parent" or parents. Reproduction is a fundamental feature of all known life; each individual o ...
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. Death also has a role in
competition Competition is a rivalry where two or more parties strive for a common goal which cannot be shared: where one's gain is the other's loss (an example of which is a zero-sum game). Competition can arise between entities such as organisms, ind ...
, where if a species out-competes another, there is a risk of death for the population, especially in the case where they are directly fighting over resources.


Extinction

Death plays a role in
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 ...
, 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 n ...
, 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' ...
, due to extinction being 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.


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. However, there are exceptions, such as '' 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 Biological immortality (sometimes referred to as bio-indefinite mortality) is a state in which the rate of mortality from senescence is stable or decreasing, thus decoupling it from chronological age. Various unicellular and multicellular species, ...
. Organisms showing only asexual reproduction, such as bacteria, 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 e ...
s, like the
euglenoid Euglenids (euglenoids, or euglenophytes, formally Euglenida/Euglenoida, ICZN, or Euglenophyceae, ICBN) are one of the best-known groups of flagellates, which are excavate eukaryotes of the phylum Euglenophyta and their cell structure is typical o ...
s and many
amoebozoan Amoebozoa is a major taxonomic group containing about 2,400 described species of amoeboid protists, often possessing blunt, fingerlike, lobose pseudopods and tubular mitochondrial cristae. In traditional and currently no longer supported class ...
s, 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 a ...
or not, like the volvocine algae ''
Pandorina ''Pandorina'' is a genus of green algae composed of 8, 16, or sometimes 32 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 keystone- or pe ...
'' and ''
Chlamydomonas ''Chlamydomonas'' is a genus of green algae consisting of about 150 speciesSmith, G.M. 1955 ''Cryptogamic Botany Volume 1. Algae and Fungi'' McGraw-Hill Book Company Inc of unicellular flagellates, found in stagnant water and on damp soil, ...
,'' 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 coord ...
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 the death of somatic line as a regular, genetically regulated part of its life history.


Grief in animals

Animals have sometimes shown grief for their partners or "friends." When two chimpanzees form a bond together, sexual or not, and one of them dies, the surviving chimpanzee will show signs of grief, ripping out their hair in anger and starting to cry; if the body is removed, they will resist, they will eventually go quiet when the body is gone, but upon seeing the body again, the chimp will return to a violent state.


Death of abiotic factors

Some non-living things can be considered dead. For example, a
volcano A volcano is a rupture in the crust of a planetary-mass object, such as Earth, that allows hot lava, volcanic ash, and gases to escape from a magma chamber below the surface. On Earth, volcanoes are most often found where tectonic plates ...
, batteries, electrical components, and stars are all nonliving things that can "die," whether from destruction or cessation of function. A
volcano A volcano is a rupture in the crust of a planetary-mass object, such as Earth, that allows hot lava, volcanic ash, and gases to escape from a magma chamber below the surface. On Earth, volcanoes are most often found where tectonic plates ...
, a break in the earth's crust that allows
lava Lava is molten or partially molten rock ( magma) that has been expelled from the interior of a terrestrial planet (such as Earth) or a moon onto its surface. Lava may be erupted at a volcano or through a fracture in the crust, on land or ...
, ash, and gases to escape, has three states that it may be in, active, dormant, and extinct. An
active volcano An active volcano is a volcano which is either erupting or is likely to erupt in the future. An active volcano which is not currently erupting is known as a dormant volcano. Overview Tlocene Epoch. Most volcanoes are situated on the Pacific R ...
has recently or is currently erupting; in a
dormant volcano A volcano is a rupture in the crust of a planetary-mass object, such as Earth, that allows hot lava, volcanic ash, and gases to escape from a magma chamber below the surface. On Earth, volcanoes are most often found where tectonic plat ...
, it has not erupted for a significant amount of time, but it may erupt again; in an extinct volcano, it may be cut off from the supply of its lava and will never expected to erupt again, so the volcano can be considered to be dead. A
battery Battery most often refers to: * Electric battery, a device that provides electrical power * Battery (crime), a crime involving unlawful physical contact Battery may also refer to: Energy source *Automotive battery, a device to provide power t ...
can be considered dead after the charge is fully used up.
Electrical components An electronic component is any basic discrete device or physical entity in an electronic system used to affect electrons or their associated fields. Electronic components are mostly industrial products, available in a singular form and are n ...
are similar in this fashion, in the case that it may not be able to be used again, such as after a spill of water on the components, the component can be considered dead. Stars also have a life-span and, therefore, can die. After it starts to run out of fuel, it starts to expand, this can be analogous to the star aging. After it exhausts all fuel, it may explode in a supernova, collapse into a
black hole A black hole is a region of spacetime where gravity is so strong that nothing, including light or other electromagnetic waves, has enough energy to escape it. The theory of general relativity predicts that a sufficiently compact mass can defo ...
, or turn into a
neutron star A neutron star is the collapsed core of a massive supergiant star, which had a total mass of between 10 and 25 solar masses, possibly more if the star was especially metal-rich. Except for black holes and some hypothetical objects (e.g. w ...
.


Religious views


Buddhism

In Buddhist doctrine and practice, death plays an important role. Awareness of death 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 attain
enlightenment Enlightenment or enlighten may refer to: Age of Enlightenment * Age of Enlightenment, period in Western intellectual history from the late 17th to late 18th century, centered in France but also encompassing (alphabetically by country or culture): ...
. 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 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 a ...
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 In Buddhism, the Four Noble Truths (Sanskrit: ; pi, cattāri ariyasaccāni; "The four Arya satyas") are "the truths of the Noble Ones", the truths or realities for the "spiritually worthy ones".
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 the afterlife. 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 (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">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, each person's body will be resurrected, reuniting the spirit and body in a perfect form. This process allows the individual's soul to withstand death and transform into life after death.


Hinduism

In Hindu texts, death is described as the individual eternal spiritual ''Jiva, 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, se ...
'' (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 descriptively ...
'' (good/bad material activities based on ''
dharma 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 ...
'') 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 ...
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.


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 t ...
,'' 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, life on earth right now is a short, temporary life and a testing period for every soul. 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 B ...
'' (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 ima ...
'' (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. ( Q50:16) 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 for life over death. This is partially because death puts a cessation to the possibility of fulfilling any
commandments Commandment may refer to: * The Ten Commandments * One of the 613 mitzvot of Judaism * The Great Commandment * The New Commandment * ''Commandment'' (album), a 2007 album by Six Feet Under * ''Commandments'' (film), a 1997 film starring Aidan Qui ...
.


Language

The word "death" comes from Old English ''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, nonfinite verb form that has some of the characteristics and functions of both verbs and adjectives. More narrowly, ''participle'' has been defined as "a wo ...
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 A skeleton is the structural frame that supports the body of an animal. There are several types of skeletons, including the exoskeleton, which is the stable outer shell of an organism, the endoskeleton, which forms the support structure inside ...
". The terms "
carrion Carrion () is the decaying flesh of dead animals, including human flesh. Overview Carrion is an important food source for large carnivores and omnivores in most ecosystems. Examples of carrion-eaters (or scavengers) include crows, vultures ...
" 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 ...
are lately called "cremains".


See also

*
Deathbed A deathbed is a place where a person dies or lies during the last few hours before death. Deathbed or Death Bed may also refer to: * '' Death Bed: The Bed That Eats'', a 1977 horror film * "Death Bed (Coffee for Your Head)", a 2020 single by Powf ...
*
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, ''Wh ...
*
Death row Death row, also known as condemned row, is a place in a prison that houses inmates awaiting execution after being convicted of a capital crime and sentenced to death. The term is also used figuratively to describe the state of awaiting execution ( ...
*
Death trajectory Death trajectory refers to the pattern of dying when a patient is given a projected death date with limited or no medical recourse for the remaining existence of the individual's life. The death trajectory is dependent on the cause of death, wheth ...
*
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 r ...
*
End-of-life care End-of-life care (EoLC) refers to health care provided in the time leading up to a person's death. End-of-life care can be provided in the hours, days, or months before a person dies and encompasses care and support for a person's mental and emotio ...
*
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 neg ...
*
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. Men ...
*
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, mortal ...
*
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 ...
*
Spiritual death The concept of spiritual death has varying meanings in various uses and contexts. Buddhism Buddhadasa called ''duḥkha'' spiritual death. Sangharakshita uses the term "spiritual death" to describe one stage in a system of meditation, where insi ...
*
Survivalism (life after death) Parapsychology is the study of alleged psychic phenomena ( extrasensory perception, telepathy, precognition, clairvoyance, psychokinesis (also called telekinesis), and psychometry) and other paranormal claims, for example, those related to ...
*
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 rec ...
*
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 psychol ...


References


Bibliography

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Further reading

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External links

*
"Death"
Stanford Encyclopedia of Philosophy * *
"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 fo ...
for
NASA The National Aeronautics and Space Administration (NASA ) is an independent agency of the US federal government responsible for the civil space program, aeronautics research, and space research. NASA was established in 1958, succeedi ...
. 2021 * A biologist explains life and death in different kinds of organisms, in relation to evolution. * How the medical profession categorized causes of death. * Interviews with people dying in hospices, and portraits of them before and shortly after, death. {{Authority control Senescence