Death
Death is the end of life; it is the irreversible cessation of biological functions that sustain a living organism. Death is thought to eventually and inevitably occur in all organisms; though some organisms, such as the immortal jellyfish, are biologically immortal, they can however still die from means other than the effects of aging. Something that is not considered an organism may be said "to die" in a figurative sense when it reaches an inactive state, such as when a star runs out of fuel.
As of the early 21st century, 56 million people die per year. As of 2022, an estimated total of almost 110 billion humans have died, or roughly 94% of all humans to have ever lived. The cause of death is usually considered important, and an autopsy can be done to determine it. There are many causes, from accidents to diseases or crime and war. The most common reason is aging; the most common cause is cardiovascular disease, which is a disease that affects the heart or blood vessels. A substudy of gerontology known as biogerontology 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 for a human, often through lifestyle changes, such as calorie reduction, dieting, and exercise. The idea of lifespan extension 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. However, the development of cardiopulmonary resuscitation meant that such a state was no longer strictly irreversible. For all organisms with a brain, death can instead be focused on this organ. Brain death was then considered a more fitting option, but several definitions exist for this: some people believe that all brain functions must cease; others believe that even if the brainstem 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.
Many cultures and religions have a concept of an afterlife. There are also different customs for honoring the lifeless body, such as a funeral, cremation, or sky burial. After a death, an obituary may be posted in a newspaper, and the "survived by" kin and friends usually go through the grieving process.
Diagnosis
Definition
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 and Dharmic traditions, hold that death does 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 heartbeat and breathing, but the development of CPR and prompt defibrillation have rendered that definition inadequate because breathing and heartbeat can sometimes be restarted. This type of death where circulatory and respiratory arrest happens is known as the circulatory definition of death. 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 devices, organ transplants, and artificial pacemakers.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. Suspension of consciousness must be permanent and not transient, as occurs during certain sleep stages, and especially a coma. In the case of sleep, electroencephalograms 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."
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, hypoxia, or hypothermia 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.