death

Death is the end of life in a biological organism, marked by the full cessation of its vital functions. All known multicellular living things eventually die, whether because of natural causes such as disease, or unnatural ones such as accidents. Death has also been personified throughout history as a figure to be feared and hated.

Biology

Causes

See also: List of causes of death by rate

Death has many potential causes: disease, injury, poisoning, among others. Any of these may damage tissues and organs, and disturb the inner balance that allows vitality (homeostasis). Ultimately, every cause of death in animals does so by breaking the oxygen cycle, cutting off oxygen flow to the brain. All living creatures die, even if they have no particular affliction. Furthermore, every species has its own typical life expectancy. Humans, for example, don't usually pass the 100-year mark, even when they are generally healthy and living in a secure environment. In humans, similar to most mammals, one can discern a slow deterioration in the body's vitality, which eventually results in death.

Current research aims to discover the cause of the body's natural deterioration upon entering old age. Even though findings are generally inconclusive, several theories have been proposed. One theory proposes that the body's deterioration is caused by genetic reasons, as the human genome contains a self-destructive mechanism that kicks off after a specific length of time. Another theory suggests that there is a limit on the rate of cell division which ultimately leads to cell demise (see Telomere).^[2] However, many studies show that a proper diet and nutrition together with regular physical activity can extend life expectancy.

In third world countries, inferior sanitary conditions and lack of access to medical technology makes death from infectious diseases more common than in developed countries. One such disease is tuberculosis, a bacterial disease which killed 1.7 million people in 2004.^[3]

Predation is a common cause of death for many organisms.

Definition

Historically, attempts to define the exact moment of death have been problematic. Death was once defined as the cessation of heartbeat (cardiac arrest) and of breathing, but the development of CPR and prompt defibrillation posed a challenge, rendering the previous definition inadequate. This earlier definition of death is now called "clinical death", and even after it occurs, breathing and heartbeat may be restarted in some cases. Events which were causally linked to death in the past are now prevented from having an effect; even without a functioning heart and lungs, a person can be sustained with life support devices. In addition to such extremes, there are a growing number of people who would quickly die if their organ transplants or artificial pacemakers failed.

Today, where a definition of the moment of death is required, doctors and coroners usually turn to "brain death" or "biological death": People are considered dead when the electrical activity in their brain ceases (cf. persistent vegetative state). It is presumed that a stoppage of electrical activity indicates the end of consciousness. However, suspension of consciousness must be permanent, and not transient, as occurs during sleep, and especially a coma. In the case of sleep, EEGs can easily tell the difference. Identifying the moment of death is important in cases of transplantation, as organs for transplant (the brain excluded) must be harvested as quickly as possible after the death of the body.

Among human beings, brain activity is a necessary condition to legal personhood in the United States. "It appears that once brain death has been determined … no criminal or civil liability will result from disconnecting the life-support devices." (Dority v. Superior Court of San Bernardino County, 193 Cal.Rptr. 288, 291 (1983))

However, those maintaining that only the neo-cortex of the brain is necessary for consciousness sometimes argue that only electrical activity there should be considered when defining death. Eventually it is likely that the criterion for death will be the permanent and irreversible loss of cognitive function, as evidenced by the death of the cerebral cortex. All hope of recovering human thought and personality is then gone. However, at present, in most places the more conservative definition of death — cessation of electrical activity in the whole brain, as opposed to just in the neo-cortex — has been adopted (for example the Uniform Determination Of Death Act in the United States). In 2005, the case of Terri Schiavo brought the question of brain death and artificial sustenance to the front of American politics. Generally, in such contested cases the cause of death is anoxia. Oxygen deprivation for roughly seven minutes is sufficient to kill the cerebral cortex.

Even in these cases, the determination of death can be difficult. EEGs can detect spurious electrical impulses when none exists, while there have been cases in which electrical activity in a living brain has been too low for EEGs to detect. Because of this, hospitals often have elaborate protocols for determining death involving EEGs at widely separated intervals.

There are many anecdotal references to people being declared dead by physicians and then coming back to life, sometimes days later in their own coffin, or when embalming procedures are just about to begin. Owing to significant scientific advancements in the Victorian era, some people in Great Britain became obsessively worried about living after being declared dead. Premature burial was a particular possibility which concerned many; inventors therefore created methods of alerting the outside world to one's status: these included surface bells and flags connected to the coffin interior by string, and glass partitions in the coffin-lid which could be smashed by a hammer or a system of pulleys (what many failed to realize was that the pulley system would either not work because of the soil outside the coffin, or that the glass would smash in the person's face, covering them in broken glass and earth).

A first responder is not authorized to pronounce a patient dead. Some EMT training manuals specifically state that a person is not to be assumed dead unless there are clear and obvious indications that death has occurred.^{citation needed]} These indications include mortal decapitation, rigor mortis (rigidity of the body), livor mortis (blood pooling in the part of the body at lowest elevation), decomposition, incineration, or other bodily damage that is clearly inconsistent with life. If there is any possibility of life and in the absence of a do not resuscitate (DNR) order, emergency workers are instructed to begin rescue and not end it until a patient has been brought to a hospital to be examined by a physician. This frequently leads to situation of a patient being pronounced dead on arrival (DOA).

In cases of electrocution, CPR for an hour or longer can allow stunned nerves to recover, allowing an apparently-dead person to survive. People found unconscious under icy water may survive if their faces are kept continuously cold until they arrive at an emergency room.^{citation needed]} This "diving response", in which metabolic activity and oxygen requirements are minimal, is something we share with cetaceans (whales, dolphins, etc) called the mammalian diving reflex. ^{citation needed]}

As medical technologies advance, ideas about when death occurs may have to be re-evaluated in light of the ability to restore a person to vitality after longer periods of apparent death (as has already happened when cessation of heartbeat was seen to be 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 actually occurs, though the concept has few practical applications outside of the field of cryonics.

Death in culture

Settlement of dead bodies

See also: funeral

In most cultures, before the onset of significant decay, the body undergoes some type of ritual disposal, usually either cremation or interment in a tomb. Cremation is a very old and quite common custom, if one takes into account the sheer numbers of next of kin (of dead) practicing it. The act of cremation exemplifies the belief of the concept of "ashes to ashes". The other modes of disposal include interment in a grave, but may also be a sarcophagus, crypt, sepulchre, or ossuary, a mound or barrow, or a monumental surface structure such as a mausoleum (exemplified by the Taj Mahal) or a pyramid (as exemplified by the Great Pyramid of Giza).

In Tibet, one method of corpse disposal is sky burial, which involves placing the body of the deceased on high ground (a mountain) and leaving it for birds of prey to dispose of. Sometimes this is because in some religious views, birds of prey are carriers of the soul to the heavens, but at other times this simply reflects the fact that when terrain (as in Tibet) makes the ground too hard to dig, there are few trees around to burn and the local religion (Buddhism) believes that the body after death is only an empty shell, there are more practical ways of disposing of a body, such as leaving it for animals to consume.

In certain cultures, efforts are made to retard the decay processes before burial (resulting even in the retardation of decay processes after the burial), as in mummification or embalming. This happens during or after a funeral ceremony. Many funeral customs exist in different cultures. In some fishing or naval communities, the body is sent into the water, in what is known as burial at sea. Several mountain villages have a tradition of hanging the coffin in woods.

A new alternative is ecological burial. This is a sequence of deep-freezing, pulverisation by vibration, freeze-drying, removing metals, and burying the resulting powder, which has 30% of the body mass.

Cryonics is the process of cryopreservating of a body to liquid nitrogen temperature to stop the natural decay processes that occur after death. Those practicing cryonics hope that future technology will allow the legally deceased person to be restored to life when and if science is able to cure all disease, rejuvenate people to a youthful condition and repair damage from the cryopreservation process itself. As of 2006, there were nearly 150 people in some form of cryopreservation at one of the two largest cryonics organizations, Alcor Life Extension Foundation and the Cryonics Institute.

Space burial uses a rocket to launch the cremated remains of a body into orbit. This has been done at least 150 times.

Graves are usually grouped together in a plot of land called a cemetery or graveyard, and burials can be arranged by a funeral home, mortuary, undertaker or by a religious body such as a church or (for some Jews) the community's burial society, a charitable or voluntary body charged with these duties.

Whole body donations, made by the donor while living (or by a family member in some cases), are an important source of human cadavers used in medical education and similar training, and in research. In the United States, these gifts, along with organ donations, are governed by the Uniform Anatomical Gift Act. In addition to wishing to benefit others, individuals might choose to donate their bodies to avoid the cost of funeral arrangements; however, willed body programs often encourage families to make alternative arrangements for burial if the body is not accepted.

Settlement of legal entity

Aside from the physical disposition of the corpse, the legal entity of a person must be settled. This includes attributes such as assets and debts. Depending on the jurisdiction, laws or a will may determine the final disposition of the estate. A legal process, or probate will guide these proceedings.

Customs and superstitions

Death's finality and the relative lack of firm scientific understanding of its processes for most of human history have led to many different traditions and cultural rituals for dealing with death.

The number 4 in southeastern Asia

In China, Japan, Korea, and Taiwan the number 4 is often associated with death because the sound of the Chinese, Japanese, and Korean words for four and death are similar (for example, 사 in Korean is the Sino-Korean number 4 and the word for death, as in 뇌사 (brain death). For this reason, hospitals and hotels often omit the 4th, 14th, 24th, floors (etc.), or substitute the number '4' with the letter 'F'. Koreans are buried under a mound standing vertical in coffins made from six planks of wood. Four of the planks represent their respective four cardinal points of the compass, while a fifth represents sky and the sixth represents earth. This relates back to the importance that the Confucian society placed upon the four cardinal points having mystical powers.

Consciousness after death

Main article: Afterlife

Many cultures, past and present, have had some belief in an afterlife. Such beliefs are usually manifested in a religion, as they pertain to phenomena beyond the ordinary experience of the natural world. Through the ages, various evidence has been advanced in attempts to demonstrate the reality of an afterlife, but nothing has ever been proven about either the existence or nature of an afterlife so the topic remains highly speculative.

Personification of death

Main article: Death (personification)

Death has also been personified as a figure or fictional character in mythology and popular culture since the earliest days of storytelling. Because the reality of death has had a substantial influence on the human psyche and the development of civilization as a whole, the personification of Death as a living, sentient entity is a concept that has existed in many societies since the beginning of recorded history. In western culture, death is usually shown as a skeletal figure carrying a large scythe, and sometimes wearing a midnight black gown with a hood.

Examples of death personified are:

• In modern-day European-based folklore, Death is known as the "Grim Reaper" or "The grim spectre of death". This form typically weilds a scythe, and is sometimes portrayed riding a white horse

• In the Middle Ages, Death was imagined as a decaying or mummified human corpse, later becoming the familiar skeleton in a robe.
• Death is sometimes portrayed in fiction and occultism as Azrael, the angel of death (note that the name "Azrael" does not appear in any versions of either the Bible or the Qur'an).
• Father Time is sometimes said to be Death.
• A psychopomp is a spirit, deity, or other being whose task is to conduct the souls of the recently dead into the afterlife.

Glorification of and fascination with death

See also: Fascination with death

Whether because of its very poetic nature or because of the great mystery it presents, or both, death is and has very often been glorified in many cultures through many different means. War, crime, revenge, martyrdom, suicide and many other forms of violence involving death are often glorified by different media, often in modern times being glorified even in spite of the attempts at depicting death meant to be de-glorifying. As film critic Roger Ebert mentions in a number of articles, Francis Truffaut makes the claim that it's impossible to make an anti-war film, as any depiction of war ends up glorifying it. The most prevalent and permanent form of death's glorification is through artistic expression. Through song, such as Knockin' on Heaven's Door or Bullet in the Head, many artists show death through poetic analogy or even as a poetic analogy, as in the latter mentioned song. Events such as The Charge of the Light Brigade and The Battle of the Alamo have served as inspirations for artistic depictions of and myths regarding death.

Whether death is in fact glorious is a subjective matter and depends on one's belief in the presence or lack of an afterlife and their perception of the goodness or badness of said belief in what follows death. That is to say, if one believes there is no afterlife but that 'soaring' into death in some way, perhaps violently or in some other shocking or poetic way, is still glorious and better, despite there being nothing but unconsciousness in death by their view. A perhaps more common view, that there is an afterlife, makes the chief struggle that of being able to overcome one's fear of death to proceed into that afterlife, or perhaps reassuring one's belief in said afterlife. Some believe death to be the beauty of life.

The presence of this glorification, of course, and its opposite, the demonization or avoidance of death as a terrible thing, is such a prevalent topic because of the prevalence of death in society and the eventual death of every living thing. Of note, but generally the most common reaction to death, is an intense fear of or sometimes hatred of and frustration with it.