Immortality

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The Fountain of Eternal Life in Cleveland, Ohio is described as symbolizing "Man rising above death, reaching upward to God and toward Peace."^[1]

Immortality is eternal life, being exempt from death, unending existence. Some modern species may possess biological immortality.

Certain scientists, futurists, and philosophers have theorized about the immortality of the human body, with some suggesting that human immortality may be achievable in the first few decades of the 21st century. Other advocates believe that life extension is a more achievable goal in the short term, with immortality awaiting further research breakthroughs. The absence of aging would provide humans with biological immortality, but not invulnerability to death by disease or physical trauma; although mind uploading could solve that if it proved possible. Whether the process of internal endoimmortality is delivered within the upcoming years depends chiefly on research (and in neuron research in the case of endoimmortality through an immortalized cell line) in the former view and perhaps is an awaited goal in the latter case.

In religious contexts, immortality is often stated to be one of the promises of God (or other deities) to human beings who show goodness or else follow divine law. What form an unending human life would take, or whether an immaterial soul exists and possesses immortality, has been a major point of focus of religion, as well as the subject of speculation, fantasy, and debate.

Definitions

Scientific

Life extension technologies promise a path to complete rejuvenation. Cryonics holds out the hope that the dead can be revived in the future, following sufficient medical advancements. While, as shown with creatures such as hydra and planarian worms, it is indeed possible for a creature to be biologically immortal, it is not known if it is possible for humans.

Mind uploading is the transference of brain states from a human brain to an alternative medium providing similar functionality. Assuming the process to be possible and repeatable, this would provide immortality to the computation of the original brain, as predicted by futurists such as Ray Kurzweil.^[4]

Religious

The belief in an afterlife is a fundamental tenet of most religions, including Hinduism, Buddhism, Jainism, Sikhism, Christianity, Zoroastrianism, Islam, Judaism, and the Bahá'í Faith; however, the concept of an immortal soul is not. The "soul" itself has different meanings and is not used in the same way in different religions and different denominations of a religion. For example, various branches of Christianity have disagreeing views on the soul's immortality and its relation to the body.

Physical immortality

Physical immortality is a state of life that allows a person to avoid death and maintain conscious thought. It can mean the unending existence of a person from a physical source other than organic life, such as a computer. Active pursuit of physical immortality can either be based on scientific trends, such as cryonics, digital immortality, breakthroughs in rejuvenation or predictions of an impending technological singularity, or because of a spiritual belief, such as those held by Rastafarians or Rebirthers.

Causes of death

There are three main causes of death: aging, disease and physical trauma.^[5] Such issues can be resolved with the solutions provided in research to any end providing such alternate theories at present that require unification.

Aging

Aubrey de Grey, a leading researcher in the field,^[6] defines aging as "a collection of cumulative changes to the molecular and cellular structure of an adult organism, which result in essential metabolic processes, but which also, once they progress far enough, increasingly disrupt metabolism, resulting in pathology and death." The current causes of aging in humans are cell loss (without replacement), DNA damage, oncogenic nuclear mutations and epimutations, cell senescence, mitochondrial mutations, lysosomal aggregates, extracellular aggregates, random extracellular cross-linking, immune system decline, and endocrine changes. Eliminating aging would require finding a solution to each of these causes, a program de Grey calls engineered negligible senescence. There is also a huge body of knowledge indicating that change is characterized by the loss of molecular fidelity.^[7]

Disease

Disease is theoretically surmountable via technology. In short, it is an abnormal condition affecting the body of an organism, something the body shouldn't typically have to deal with its natural make up.^[8] Human understanding of genetics is leading to cures and treatments for a myriad of previously incurable diseases. The mechanisms by which other diseases do damage are becoming better understood. Sophisticated methods of detecting diseases early are being developed. Preventative medicine is becoming better understood. Neurodegenerative diseases like Parkinson's and Alzheimer's may soon be curable with the use of stem cells. Breakthroughs in cell biology and telomere research are leading to treatments for cancer. Vaccines are being researched for AIDS and tuberculosis. Genes associated with type 1 diabetes and certain types of cancer have been discovered, allowing for new therapies to be developed. Artificial devices attached directly to the nervous system may restore sight to the blind. Drugs are being developed to treat a myriad of other diseases and ailments.

Trauma

Physical trauma would remain as a threat to perpetual physical life, as an otherwise immortal person would still be subject to unforeseen accidents or catastrophes. The speed and quality of paramedic response remains a determining factor in surviving severe trauma.^[9] A body that could automatically repair itself from severe trauma, such as speculated uses for nanotechnology, would mitigate this factor. Being the seat of consciousness, the brain cannot be risked to trauma if a continuous physical life is to be maintained. This aversion to trauma risk to the brain would naturally result in significant behavioral changes that would render physical immortality undesirable for some people.

Environmental change

Organisms otherwise unaffected by these causes of death would still face the problem of obtaining sustenance (whether from currently available agricultural processes or from hypothetical future technological processes) in the face of changing availability of suitable resources as environmental conditions change. After avoiding aging, disease, and trauma, you could still starve to death.

If there is no limitation on the degree of gradual mitigation of risk then it is possible that the cumulative probability of death over an infinite horizon is less than certainty, even when the risk of fatal trauma in any finite period is greater than zero. Mathematically, this is an aspect of achieving "actuarial escape velocity"

Biological immortality

Human chromosomes (grey) capped by telomeres (white)

Biological immortality is an absence of aging. Specifically it's the absence of a sustained increase in rate of mortality as a function of chronological age. A cell or organism that does not experience aging, or ceases to age at some point, is biologically immortal.

Biologists have chosen the word "immortal" to designate cells that are not limited by the Hayflick limit, where cells no longer divide because of DNA damage or shortened telomeres. The first and still most widely used immortal cell line is HeLa, developed from cells taken from the malignant cervical tumor of Henrietta Lacks without her consent in 1951. Prior to the 1961 work of Leonard Hayflick, there was the erroneous belief fostered by Alexis Carrel that all normal somatic cells are immortal. By preventing cells from reaching senescence one can achieve biological immortality; telomeres, a "cap" at the end of DNA, are thought to be the cause of cell aging. Every time a cell divides the telomere becomes a bit shorter; when it is finally worn down, the cell is unable to split and dies.  Telomerase is an enzyme which rebuilds the telomeres in stem cells and cancer cells, allowing them to replicate an infinite number of times.^[10] No definitive work has yet demonstrated that telomerase can be used in human somatic cells to prevent healthy tissues from aging. On the other hand, scientists hope to be able to grow organs with the help of stem cells, allowing organ transplants without the risk of rejection, another step in extending human life expectancy. These technologies are the subject of ongoing research, and are not yet realized.^[11]

Biologically immortal species

Life defined as biologically immortal is still susceptible to causes of death besides aging, including disease and trauma, as defined above. Notable immortal species include:

• Bacteria – Bacteria reproduce through binary fission. A parent bacterium splits itself into two identical daughter cells which eventually then split themselves in half. This process repeats, thus making the bacterium essentially immortal. A 2005 PLoS Biology paper^[12] suggests that after each division the daughter cells can be identified as the older and the younger, and the older is slightly smaller, weaker, and more likely to die than the younger.^[13]
• Turritopsis dohrnii, a jellyfish (phylum Cnidaria, class Hydrozoa, order Anthoathecata), after becoming a sexually mature adult, can transform itself back into a polyp using the cell conversion process of transdifferentiation.^[14] Turritopsis dohrnii repeats this cycle, meaning that it may have an indefinite lifespan.^[14] Its immortal adaptation has allowed it to spread from its original habitat in the Caribbean to "all over the world".^[15][16]
• Hydra is a genus belonging to the phylum Cnidaria, the class Hydrozoa and the order Anthomedusae. They are simple fresh-water predatory animals possessing radial symmetry.^[17][18]
• Bristlecone pines are speculated to be potentially immortal;^{[citation needed]} the oldest known living specimen is over 5,000 years old.

Evolution of aging

As the existence of biologically immortal species demonstrates, there is no thermodynamic necessity for senescence: a defining feature of life is that it takes in free energy from the environment and unloads its entropy as waste. Living systems can even build themselves up from seed, and routinely repair themselves. Aging is therefore presumed to be a byproduct of evolution, but why mortality should be selected for remains a subject of research and debate. Programmed cell death and the telomere "end replication problem" are found even in the earliest and simplest of organisms.^[19] This may be a tradeoff between selecting for cancer and selecting for aging.^[20]

Modern theories on the evolution of aging include the following:

• Mutation accumulation is a theory formulated by Peter Medawar in 1952 to explain how evolution would select for aging. Essentially, aging is never selected against, as organisms have offspring before the mortal mutations surface in an individual.
• Antagonistic pleiotropy is a theory proposed as an alternative by George C. Williams, a critic of Medawar, in 1957. In antagonistic pleiotropy, genes carry effects that are both beneficial and detrimental. In essence this refers to genes that offer benefits early in life, but exact a cost later on, i.e. decline and death.^[21]
• The disposable soma theory was proposed in 1977 by Thomas Kirkwood, which states that an individual body must allocate energy for metabolism, reproduction, and maintenance, and must compromise when there is food scarcity. Compromise in allocating energy to the repair function is what causes the body gradually to deteriorate with age, according to Kirkwood.^[22]

Prospects for human biological immortality

Life-extending substances

There are some known naturally occurring and artificially produced chemicals that may increase the lifetime or life-expectancy of a person or organism, such as resveratrol.^[23][24]

Some scientists believe that boosting the amount or proportion of telomerase in the body, a naturally forming enzyme that helps maintain the protective caps at the ends of chromosomes, could prevent cells from dying and so may ultimately lead to extended, healthier lifespans. A team of researchers at the Spanish National Cancer Centre (Madrid) tested the hypothesis on mice. It was found that those mice which were genetically engineered to produce 10 times the normal levels of telomerase lived 50% longer than normal mice.^[25]

In normal circumstances, without the presence of telomerase, if a cell divides repeatedly, at some point all the progeny will reach their Hayflick limit. With the presence of telomerase, each dividing cell can replace the lost bit of DNA, and any single cell can then divide unbounded. While this unbounded growth property has excited many researchers, caution is warranted in exploiting this property, as exactly this same unbounded growth is a crucial step in enabling cancerous growth. If an organism can replicate its body cells faster, then it would theoretically stop aging.

Embryonic stem cells express telomerase, which allows them to divide repeatedly and form the individual. In adults, telomerase is highly expressed in cells that need to divide regularly (e.g., in the immune system), whereas most somatic cells express it only at very low levels in a cell-cycle dependent manner.

Technological immortality, biological machines, and "swallowing the doctor"

Technological immortality is the prospect for much longer life spans made possible by scientific advances in a variety of fields: nanotechnology, emergency room procedures, genetics, biological engineering, regenerative medicine, microbiology, and others. Contemporary life spans in the advanced industrial societies are already markedly longer than those of the past because of better nutrition, availability of health care, standard of living and bio-medical scientific advances. Technological immortality predicts further progress for the same reasons over the near term. An important aspect of current scientific thinking about immortality is that some combination of human cloning, cryonics or nanotechnology will play an essential role in extreme life extension. Robert Freitas, a nanorobotics theorist, suggests tiny medical nanorobots could be created to go through human bloodstreams, find dangerous things like cancer cells and bacteria, and destroy them.^[26] Freitas anticipates that gene-therapies and nanotechnology will eventually make the human body effectively self-sustainable and capable of living indefinitely in empty space, short of severe brain trauma. This supports the theory that we will be able to continually create biological or synthetic replacement parts to replace damaged or dying ones. Future advances in nanomedicine could give rise to life extension through the repair of many processes thought to be responsible for aging. K. Eric Drexler, one of the founders of nanotechnology, postulated cell repair devices, including ones operating within cells and utilizing as yet hypothetical biological machines, in his 1986 book Engines of Creation. Raymond Kurzweil, a futurist and transhumanist, stated in his book The Singularity Is Near that he believes that advanced medical nanorobotics could completely remedy the effects of aging by 2030.^[27] According to Richard Feynman, it was his former graduate student and collaborator Albert Hibbs who originally suggested to him (circa 1959) the idea of a medical use for Feynman's theoretical micromachines (see biological machine). Hibbs suggested that certain repair machines might one day be reduced in size to the point that it would, in theory, be possible to (as Feynman put it) "swallow the doctor". The idea was incorporated into Feynman's 1959 essay There's Plenty of Room at the Bottom.^[28]

Cryonics

Cryonics, the practice of preserving organisms (either intact specimens or only their brains) for possible future revival by storing them at cryogenic temperatures where metabolism and decay are almost completely stopped, can be used to 'pause' for those who believe that life extension technologies will not develop sufficiently within their lifetime. Ideally, cryonics would allow clinically dead people to be brought back in the future after cures to the patients' diseases have been discovered and aging is reversible. Modern cryonics procedures use a process called vitrification which creates a glass-like state rather than freezing as the body is brought to low temperatures. This process reduces the risk of ice crystals damaging the cell-structure, which would be especially detrimental to cell structures in the brain, as their minute adjustment evokes the individual's mind.

Mind-to-computer uploading

One idea that has been advanced involves uploading an individual's habits and memories via direct mind-computer interface. The individual's memory may be loaded to a computer or to a new organic body. Extropian futurists like Moravec and Kurzweil have proposed that, thanks to exponentially growing computing power, it will someday be possible to upload human consciousness onto a computer system, and exist indefinitely in a virtual environment. This could be accomplished via advanced cybernetics, where computer hardware would initially be installed in the brain to help sort memory or accelerate thought processes. Components would be added gradually until the person's entire brain functions were handled by artificial devices, avoiding sharp transitions that would lead to issues of identity, thus running the risk of the person to be declared dead and thus not be a legitimate owner of his or her property. After this point, the human body could be treated as an optional accessory and the program implementing the person could be transferred to any sufficiently powerful computer. Another possible mechanism for mind upload is to perform a detailed scan of an individual's original, organic brain and simulate the entire structure in a computer. What level of detail such scans and simulations would need to achieve to emulate awareness, and whether the scanning process would destroy the brain, is still to be determined.^[29] Whatever the route to mind upload, persons in this state could then be considered essentially immortal, short of loss or traumatic destruction of the machines that maintained them.^{[clarification needed]}

Cybernetics

Transforming a human into a cyborg can include brain implants or extracting a human processing unit and placing it in a robotic life-support system. Even replacing biological organs with robotic ones could increase life span (e.g. pace makers) and depending on the definition, many technological upgrades to the body, like genetic modifications or the addition of nanobots would qualify an individual as a cyborg. Some people believe that such modifications would make one impervious to aging and disease and theoretically immortal unless killed or destroyed.

Religious views

As late as 1952, the editorial staff of the Syntopicon found in their compilation of the Great Books of the Western World, that "The philosophical issue concerning immortality cannot be separated from issues concerning the existence and nature of man's soul."^[30] Thus, the vast majority of speculation regarding immortality before the 21st century was regarding the nature of the afterlife.

Ancient Greek religion

Immortality in ancient Greek religion originally always included an eternal union of body and soul as can be seen in Homer, Hesiod, and various other ancient texts. The soul was considered to have an eternal existence in Hades, but without the body the soul was considered dead. Although almost everybody had nothing to look forward to but an eternal existence as a disembodied dead soul, a number of men and women were considered to have gained physical immortality and been brought to live forever in either Elysium, the Islands of the Blessed, heaven, the ocean or literally right under the ground. Among these were Amphiaraus, Ganymede, Ino, Iphigenia, Menelaus, Peleus, and a great part of those who fought in the Trojan and Theban wars. Some were considered to have died and been resurrected before they achieved physical immortality. Asclepius was killed by Zeus only to be resurrected and transformed into a major deity. In some versions of the Trojan War myth, Achilles, after being killed, was snatched from his funeral pyre by his divine mother Thetis, resurrected, and brought to an immortal existence in either Leuce, the Elysian plains, or the Islands of the Blessed.  Memnon, who was killed by Achilles, seems to have received a similar fate. Alcmene, Castor, Heracles, and Melicertes were also among the figures sometimes considered to have been resurrected to physical immortality. According to Herodotus' Histories, the 7th century BC sage Aristeas of Proconnesus was first found dead, after which his body disappeared from a locked room. Later he was found not only to have been resurrected but to have gained immortality.

The philosophical idea of an immortal soul was a belief first appearing with either Pherecydes or the Orphics, and most importantly advocated by Plato and his followers. This, however, never became the general norm in Hellenistic thought. As may be witnessed even into the Christian era, not least by the complaints of various philosophers over popular beliefs, many or perhaps most traditional Greeks maintained the conviction that certain individuals were resurrected from the dead and made physically immortal and that others could only look forward to an existence as disembodied and dead, though everlasting, souls. The parallel between these traditional beliefs and the later resurrection of Jesus was not lost on the early Christians, as Justin Martyr argued: "when we say ... Jesus Christ, our teacher, was crucified and died, and rose again, and ascended into heaven, we propose nothing different from what you believe regarding those whom you consider sons of Zeus." (1 Apol. 21).

Buddhism

The goal of Hinayana is Arhatship and Nirvana. By contrast, the goal of Mahayana is Buddhahood.
According to one Tibetan Buddhist teaching, Dzogchen, individuals can transform the physical body into an immortal body of light called the rainbow body.

Christianity

Adam and Eve condemned to mortality. Hans Holbein the Younger, Danse Macabre, 16th century

Christian theology holds that Adam and Eve lost physical immortality for themselves and all their descendants in the Fall of Man, although this initial "imperishability of the bodily frame of man" was "a preternatural condition".^[31] Christians who profess the Nicene Creed believe that every dead person (whether they believed in Christ or not) will be resurrected from the dead at the Second Coming, and this belief is known as Universal resurrection.

N.T. Wright, a theologian and former Bishop of Durham, has said many people forget the physical aspect of what Jesus promised. He told Time: "Jesus' resurrection marks the beginning of a restoration that he will complete upon his return. Part of this will be the resurrection of all the dead, who will 'awake', be embodied and participate in the renewal. Wright says John Polkinghorne, a physicist and a priest, has put it this way: 'God will download our software onto his hardware until the time he gives us new hardware to run the software again for ourselves.' That gets to two things nicely: that the period after death (the Intermediate state) is a period when we are in God's presence but not active in our own bodies, and also that the more important transformation will be when we are again embodied and administering Christ's kingdom."^[32] This kingdom will consist of Heaven and Earth "joined together in a new creation", he said.

Hinduism

Representation of a soul undergoing punarjanma. Illustration from Hinduism Today, 2004

Hindus believe in an immortal soul which is reincarnated after death. According to Hinduism, people repeat a process of life, death, and rebirth in a cycle called samsara. If they live their life well, their karma improves and their station in the next life will be higher, and conversely lower if they live their life poorly. After many life times of perfecting its karma, the soul is freed from the cycle and lives in perpetual bliss. There is no place of eternal torment in Hinduism, although if a soul consistently lives very evil lives, it could work its way down to the very bottom of the cycle.

There are explicit renderings in the Upanishads alluding to a physically immortal state brought about by purification, and sublimation of the 5 elements that make up the body. For example, in the Shvetashvatara Upanishad (Chapter 2, Verse 12), it is stated "When earth, water fire, air and akasa arise, that is to say, when the five attributes of the elements, mentioned in the books on yoga, become manifest then the yogi's body becomes purified by the fire of yoga and he is free from illness, old age and death."

Another view of immortality is traced to the Vedic tradition by the interpretation of Maharishi Mahesh Yogi:

That man indeed whom these (contacts)
do not disturb, who is even-minded in
pleasure and pain, steadfast, he is fit
for immortality, O best of men.^[33]

To Maharishi Mahesh Yogi, the verse means, "Once a man has become established in the understanding of the permanent reality of life, his mind rises above the influence of pleasure and pain. Such an unshakable man passes beyond the influence of death and in the permanent phase of life: he attains eternal life ... A man established in the understanding of the unlimited abundance of absolute existence is naturally free from existence of the relative order. This is what gives him the status of immortal life."^[33]

An Indian Tamil saint known as Vallalar claimed to have achieved immortality before disappearing forever from a locked room in 1874.^[34][35]

Judaism

The traditional concept of an immaterial and immortal soul distinct from the body was not found in Judaism before the Babylonian Exile, but developed as a result of interaction with Persian and Hellenistic philosophies. Accordingly, the Hebrew word nephesh, although translated as "soul" in some older English Bibles, actually has a meaning closer to "living being". Nephesh was rendered in the Septuagint as ψυχή (psūchê), the Greek word for soul.

The only Hebrew word traditionally translated "soul" (nephesh) in English language Bibles refers to a living, breathing conscious body, rather than to an immortal soul.^[36] In the New Testament, the Greek word traditionally translated "soul" (ψυχή) has substantially the same meaning as the Hebrew, without reference to an immortal soul.^[37] ‘Soul’ may refer to the whole person, the self: ‘three thousand souls’ were converted in Acts 2:41 (see Acts 3:23).

The Hebrew Bible speaks about Sheol (שאול), originally a synonym of the grave-the repository of the dead or the cessation of existence until the resurrection of the dead. This doctrine of resurrection is mentioned explicitly only in Daniel 12:1–4 although it may be implied in several other texts. New theories arose concerning Sheol during the intertestamental period.

The views about immortality in Judaism is perhaps best exemplified by the various references to this in Second Temple Period. The concept of resurrection of the physical body is found in 2 Maccabees, according to which it will happen through recreation of the flesh.^[38] Resurrection of the dead also appears in detail in the extra-canonical books of Enoch,^[39] and in Apocalypse of Baruch.^[40] According to the British scholar in ancient Judaism Philip R. Davies, there is “little or no clear reference … either to immortality or to resurrection from the dead” in the Dead Sea scrolls texts.^[41] Both Josephus and the New Testament record that the Sadducees did not believe in an afterlife,^[42] but the sources vary on the beliefs of the Pharisees. The New Testament claims that the Pharisees believed in the resurrection, but does not specify whether this included the flesh or not.^[43] According to Josephus, who himself was a Pharisee, the Pharisees held that only the soul was immortal and the souls of good people will be reincarnated and “pass into other bodies,” while “the souls of the wicked will suffer eternal punishment.” ^[44] Jubilees seems to refer to the resurrection of the soul only, or to a more general idea of an immortal soul.^[45]

Rabbinic Judaism claims that the righteous dead will be resurrected in the Messianic Age with the coming of the messiah. They will then be granted immortality in a perfect world. The wicked dead, on the other hand, will not be resurrected at all. This is not the only Jewish belief about the afterlife. The Tanakh is not specific about the afterlife, so there are wide differences in views and explanations among believers.

Taoism

It is repeatedly stated in Lüshi Chunqiu that death is unavoidable.^[46] Henri Maspero noted that many scholarly works frame Taoism as a school of thought focused on the quest for immortality.^[47] Isabelle Robinet asserts that Taoism is better understood as a way of life than as a religion, and that its adherents do not approach or view Taoism the way non-Taoist historians have done.^[48] In the Tractate of Actions and their Retributions, a traditional teaching, spiritual immortality can be rewarded to people who do a certain amount of good deeds and live a simple, pure life. A list of good deeds and sins are tallied to determine whether or not a mortal is worthy. Spiritual immortality in this definition allows the soul to leave the earthly realms of afterlife and go to pure realms in the Taoist cosmology.^[49]

Zoroastrianism

Zoroastrians believe that on the fourth day after death, the human soul leaves the body and the body remains as an empty shell. Souls would go to either heaven or hell; these concepts of the afterlife in Zoroastrianism may have influenced Abrahamic religions. The Persian word for "immortal" is associated with the month "Amurdad", meaning "deathless" in Persian, in the Iranian calendar (near the end of July). The month of Amurdad or Ameretat is celebrated in Persian culture as ancient Persians believed the "Angel of Immortality" won over the "Angel of Death" in this month.^[50]

Philosophical arguments for the immortality of the soul

Alcmaeon of Croton

Alcmaeon of Croton argued that the soul is continuously and ceaselessly in motion. The exact form of his argument is unclear, but it appears to have influenced Plato, Aristotle, and other later writers.^[51]

Plato

Plato's Phaedo advances four arguments for the soul's immortality:^[52]

• The Cyclical Argument, or Opposites Argument explains that Forms are eternal and unchanging, and as the soul always brings life, then it must not die, and is necessarily "imperishable". As the body is mortal and is subject to physical death, the soul must be its indestructible opposite. Plato then suggests the analogy of fire and cold. If the form of cold is imperishable, and fire, its opposite, was within close proximity, it would have to withdraw intact as does the soul during death. This could be likened to the idea of the opposite charges of magnets.

• The Theory of Recollection explains that we possess some non-empirical knowledge (e.g. The Form of Equality) at birth, implying the soul existed before birth to carry that knowledge. Another account of the theory is found in Plato's Meno, although in that case Socrates implies anamnesis (previous knowledge of everything) whereas he is not so bold in Phaedo.

• The Affinity Argument, explains that invisible, immortal, and incorporeal things are different from visible, mortal, and corporeal things. Our soul is of the former, while our body is of the latter, so when our bodies die and decay, our soul will continue to live.

• The Argument from Form of Life, or The Final Argument explains that the Forms, incorporeal and static entities, are the cause of all things in the world, and all things participate in Forms. For example, beautiful things participate in the Form of Beauty; the number four participates in the Form of the Even, etc. The soul, by its very nature, participates in the Form of Life, which means the soul can never die.

Plotinus

Plotinus offers a version of the argument that Kant calls "The Achilles of Rationalist Psychology". Plotinus first argues that the soul is simple, then notes that a simple being cannot decompose. Many subsequent philosophers have argued both that the soul is simple and that it must be immortal. The tradition arguably culminates with Moses Mendelssohn's Phaedon.^[53]

Metochites

Theodore Metochites argues that part of the soul's nature is to move itself, but that a given movement will cease only if what causes the movement is separated from the thing moved – an impossibility if they are one and the same.^[54]

Avicenna

Avicenna argued for the distinctness of the soul and the body, and the incorruptibility of the former.^[55]

Aquinas

The full argument for the immortality of the soul and Thomas Aquinas' elaboration of Aristotelian theory is found in Question 75 of the First Part of the Summa Theologica.^[56]

Descartes

René Descartes endorses the claim that the soul is simple, and also that this entails that it cannot decompose. Descartes does not address the possibility that the soul might suddenly disappear.^[57]

Leibniz

In early work, Gottfried Wilhelm Leibniz endorses a version of the argument from the simplicity of the soul to its immortality, but like his predecessors, he does not address the possibility that the soul might suddenly disappear. In his monadology he advances a sophisticated novel argument for the immortality of monads.^[58]

Moses Mendelssohn

Moses Mendelssohn's Phaedon is a defense of the simplicity and immortality of the soul. It is a series of three dialogues, revisiting the Platonic dialogue Phaedo, in which Socrates argues for the immortality of the soul, in preparation for his own death. Many philosophers, including Plotinus, Descartes, and Leibniz, argue that the soul is simple, and that because simples cannot decompose they must be immortal. In the Phaedon, Mendelssohn addresses gaps in earlier versions of this argument (an argument that Kant calls the Achilles of Rationalist Psychology). The Phaedon contains an original argument for the simplicity of the soul, and also an original argument that simples cannot suddenly disappear. It contains further original arguments that the soul must retain its rational capacities as long as it exists.^[59]

Ethics

The possibility of clinical immortality raises a host of medical, philosophical, and religious issues and ethical questions. These include persistent vegetative states, the nature of personality over time, technology to mimic or copy the mind or its processes, social and economic disparities created by longevity, and survival of the heat death of the universe.

Undesirability

Physical immortality has also been imagined as a form of eternal torment, as in Mary Shelley's short story "The Mortal Immortal", the protagonist of which witnesses everyone he cares about dying around him. Jorge Luis Borges explored the idea that life gets its meaning from death in the short story "The Immortal"; an entire society having achieved immortality, they found time becoming infinite, and so found no motivation for any action. In his book Thursday's Fictions, and the stage and film adaptations of it, Richard James Allen tells the story of a woman named Thursday who tries to cheat the cycle of reincarnation to get a form of eternal life. At the end of this fantastical tale, her son, Wednesday, who has witnessed the havoc his mother's quest has caused, forgoes the opportunity for immortality when it is offered to him.^[60] Likewise, the novel Tuck Everlasting depicts immortality as "falling off the wheel of life" and is viewed as a curse as opposed to a blessing. In the anime Casshern Sins humanity achieves immortality due to advances in medical technology; however, the inability of the human race to die causes Luna, a Messianic figure, to come forth and offer normal lifespans because she believed that without death, humans could not live. Ultimately, Casshern takes up the cause of death for humanity when Luna begins to restore humanity's immortality. In Anne Rice's book series The Vampire Chronicles, vampires are portrayed as immortal and ageless, but their inability to cope with the changes in the world around them means that few vampires live for much more than a century, and those who do often view their changeless form as a curse.

In his book Death, Yale philosopher Shelly Kagan argues that any form of human immortality would be undesirable. Kagan's argument takes the form of a dilemma. Either our characters remain essentially the same in an immortal afterlife, or they do not. If our characters remain basically the same—that is, if we retain more or less the desires, interests, and goals that we have now—then eventually, over an infinite stretch of time, we will get bored and find eternal life unbearably tedious. If, on the other hand, our characters are radically changed—e.g., by God periodically erasing our memories or giving us rat-like brains that never tire of certain simple pleasures—then such a person would be too different from our current self for us to care much what happens to them. Either way, Kagan argues, immortality is unattractive. The best outcome, Kagan argues, would be for humans to live as long as they desired and then to accept death gratefully as rescuing us from the unbearable tedium of immortality.^[61]

Sociology

If human beings were to achieve immortality, there would most likely be a change in the worlds' social structures. Sociologist argue that human beings' awareness of their own mortality shapes their behavior.^[62] With the advancements in medical technology in extending human life, there may need to be serious considerations made about future social structures. The world is already experiencing a global demographic shift of increasingly ageing populations with lower replacement rates.^[63] The social changes that are made to accommodate this new population shift may be able to offer insight on the possibility of an immortal society.

Politics

Although some scientists state that radical life extension, delaying and stopping aging are achievable,^[64] there are no international or national programs focused on stopping aging or on radical life extension. In 2012 in Russia, and then in the United States, Israel and the Netherlands, pro-immortality political parties were launched. They aimed to provide political support to anti-aging and radical life extension research and technologies and at the same time transition to the next step, radical life extension, life without aging, and finally, immortality and aim to make possible access to such technologies to most currently living people.^[65]

Symbols

The ankh

There are numerous symbols representing immortality. The ankh is an Egyptian symbol of life that holds connotations of immortality when depicted in the hands of the gods and pharaohs, who were seen as having control over the journey of life. The Möbius strip in the shape of a trefoil knot is another symbol of immortality. Most symbolic representations of infinity or the life cycle are often used to represent immortality depending on the context they are placed in. Other examples include the Ouroboros, the Chinese fungus of longevity, the ten kanji, the phoenix, the peacock in Christianity,^[66] and the colors amaranth (in Western culture) and peach (in Chinese culture).

Fiction

Immortality is a popular subject in fiction, as it explores humanity's deep-seated fears and comprehension of its own mortality. Immortal beings and species abound in fiction, especially fantasy fiction, and the meaning of "immortal" tends to vary. The Epic of Gilgamesh, one of the first literary works, is primarily a quest of a hero seeking to become immortal.^[6]

Some fictional beings are completely immortal (or very nearly so) in that they are immune to death by injury, disease and age. Sometimes such powerful immortals can only be killed by each other, as is the case with the Q from the Star Trek series. Even if something can't be killed, a common plot device involves putting an immortal being into a slumber or limbo, as is done with Morgoth in J. R. R. Tolkien's The Silmarillion and the Dreaming God of Pathways Into Darkness. Storytellers often make it a point to give weaknesses to even the most indestructible of beings. For instance, Superman is supposed to be invulnerable, yet his enemies were able to exploit his now-infamous weakness: Kryptonite. (See also Achilles' heel.)

Many fictitious species are said to be immortal if they cannot die of old age, even though they can be killed through other means, such as injury. Modern fantasy elves often exhibit this form of immortality. Other creatures, such as vampires and the immortals in the film Highlander, can only die from beheading. The classic and stereotypical vampire is typically slain by one of several very specific means, including a silver bullet (or piercing with other silver weapons), a stake through the heart (perhaps made of consecrated wood), or by exposing them to sunlight.

Strategies for Engineered Negligible Senescence

From Wikipedia, the free encyclopedia

 

Strategies for Engineered Negligible Senescence (SENS) is the term coined by British biogerontologist Aubrey de Grey for the diverse range of regenerative medical therapies, either planned or currently in development, for the periodical repair of all age-related damage to human tissue with the ultimate purpose of maintaining a state of negligible senescence in the patient, thereby postponing age-associated disease for as long as the therapies are reapplied.

The term "negligible senescence" was first used in the early 1990s by professor Caleb Finch to describe organisms such as lobsters and hydras, which do not show symptoms of aging. The term "engineered negligible senescence" first appeared in print in Aubrey de Grey's 1999 book The Mitochondrial Free Radical Theory of Aging,^[3] and was later prefaced with the term "strategies" in the article Time to Talk SENS: Critiquing the Immutability of Human Aging^[4] De Grey called SENS a "goal-directed rather than curiosity-driven"^[5] approach to the science of aging, and "an effort to expand regenerative medicine into the territory of aging".^[6] To this end, SENS identifies seven categories of aging "damage" and a specific regenerative medical proposal for treating each.

While many biogerontologists find it "worthy of discussion"^[7][8] and SENS conferences feature important research in the field,^[9][10] some contend that the ultimate goals of de Grey's programme are too speculative given the current state of technology, referring to it as "fantasy rather than science".^[11][12]

Framework

The arrows with flat heads are a notation meaning "inhibits," used in the literature of gene expression and gene regulation.

The ultimate objective of SENS is the eventual elimination of age-related diseases and infirmity by repeatedly reducing the state of senescence in the organism. The SENS project consists in implementing a series of periodic medical interventions designed to repair, prevent or render irrelevant all the types of molecular and cellular damage that cause age-related pathology and degeneration, in order to avoid debilitation and death from age-related causes.^[2]

De Grey defines aging as "the set of accumulated side effects from metabolism that eventually kills us", and, more specifically, as follows: "a collection of cumulative changes to the molecular and cellular structure of an adult organism, which result in essential metabolic processes, but which also, once they progress far enough, increasingly disrupt metabolism, resulting in pathology and death."^[13] He adds: "geriatrics is the attempt to stop damage from causing pathology; traditional gerontology is the attempt to stop metabolism from causing damage; and the SENS (engineering) approach is to eliminate the damage periodically, so keeping its abundance below the level that causes any pathology." The SENS approach to biomedical gerontology is thus distinctive because of its emphasis on tissue rejuvenation rather than attempting to slow the aging process.

By enumerating the various differences between young and old tissue identified by the science of biogerontology, a 'damage' report was drawn, which in turn formed the basis of the SENS strategy. The results fell into seven main categories of 'damage', seven alterations whose reversal would constitute negligible senescence:

1. cell loss or atrophy (without replacement),^[4][13][14]
2. oncogenic nuclear mutations and epimutations,^[15][16][17]
3. cell senescence (Death-resistant cells),^[18][19]
4. mitochondrial mutations,^[20][21]
5. Intracellular junk or junk inside cells (lysosomal aggregates),^[22][23]
6. extracellular junk or junk outside cells (extracellular aggregates),^[18][19]
7. random extracellular cross-linking.^[18][19]

For each of these areas SENS offers at least one strategy, with a research and a clinical component. The clinical component is required because in some of the proposed therapies, feasibility has already been proven, but not completely applied and approved for human trials. These strategies do not presuppose that the underlying metabolic mechanisms of aging be fully understood, only that we take into account the form senescence takes as directly observable to science, and described in scientific literature..

Types of aging damage and treatment schemes

Nuclear mutations/epimutations—OncoSENS

These are changes to the nuclear DNA (nDNA), or to proteins which bind to the nDNA. Certain mutations can lead to cancer.

This would need to be corrected in order to prevent or cure cancer. SENS focuses on a strategy called "whole-body interdiction of lengthening telomeres" (WILT), which would be made possible by periodic regenerative medicine treatments.

Mitochondrial mutations—MitoSENS

Mitochondria are components in our cells that are important for energy production. Because of the highly oxidative environment in mitochondria and their lack of the sophisticated repair systems, mitochondrial mutations are believed to be a major cause of progressive cellular degeneration.

This would be corrected by allotopic expression—copying the DNA for mitochondria completely within the cellular nucleus, where it is better protected. De Grey argues that experimental evidence demonstrates that the operation is feasible, however, a 2003 study showed that some mitochondrial proteins are too hydrophobic to survive the transport from the cytoplasm to the mitochondria.^[24]

Intracellular junk—LysoSENS

Our cells are constantly breaking down proteins and other molecules that are no longer useful or which can be harmful. Those molecules which can’t be digested accumulate as junk inside our cells, which is detected in the form of lipofuscin granules. Atherosclerosis, macular degeneration, liver spots on the skin and all kinds of neurodegenerative diseases (such as Alzheimer's disease) are associated with this problem.

Junk inside cells might be removed by adding new enzymes to the cell's natural digestion organ, the lysosome. These enzymes would be taken from bacteria, molds and other organisms that are known to completely digest animal bodies.

Extracellular junk—AmyloSENS

Harmful junk protein can accumulate outside of our cells. Junk here means useless things accumulated by a body, but which cannot be digested or removed by its processes, such as the amyloid plaques characteristic of Alzheimer's disease and other amyloidoses.

Junk outside cells might be removed by enhanced phagocytosis (the normal process used by the immune system), and small drugs able to break chemical beta-bonds. The large junk in this class can be removed surgically.

Cell loss and atrophy—RepleniSENS

Some of the cells in our bodies cannot be replaced, or can be only replaced very slowly—more slowly than they die. This decrease in cell number affects some of the most important tissues of the body. Muscle cells are lost in skeletal muscles and the heart, causing them to become frailer with age. Loss of neurons in the substantia nigra causes Parkinson's disease, while loss of immune cells impairs the immune system.

This can be partly corrected by therapies involving exercise and growth factors, but stem cell therapy, regenerative medicine and tissue engineering are almost certainly required for any more than just partial replacement of lost cells.

Cell senescence—ApoptoSENS

Senescence is a phenomenon where the cells are no longer able to divide, but also do not die and let others divide. They may also do other harmful things, like secreting proteins. Degeneration of joints, immune senescence, accumulation of visceral fat and type 2 diabetes are caused by this. Cells sometimes enter a state of resistance to signals sent, as part of a process called apoptosis, to instruct cells to destroy themselves.

Cells in this state could be eliminated by forcing them to apoptose (via suicide genes, vaccines, or recently discovered senolytic agents), and healthy cells would multiply to replace them.

Extracellular crosslinks—GlycoSENS

Cells are held together by special linking proteins. When too many cross-links form between cells in a tissue, the tissue can lose its elasticity and cause problems including arteriosclerosis, presbyopia and weakened skin texture. These are chemical bonds between structures that are part of the body, but not within a cell. In senescent people many of these become brittle and weak.

SENS proposes to further develop small-molecular drugs and enzymes to break links caused by sugar-bonding, known as advanced glycation endproducts, and other common forms of chemical linking.

Scientific controversy

While some fields mentioned as branches of SENS are broadly supported by the medical research community, e.g., stem cell research (RepleniSENS), anti-Alzheimers research (AmyloSENS) and oncogenomics (OncoSENS), the SENS programme as a whole has been a highly controversial proposal, with many critics arguing that the SENS agenda is fanciful and the highly complicated biomedical phenomena involved in the aging process contain too many unknowns for SENS to be fully implementable in the foreseeable future. Cancer may well deserve special attention as an aging-associated disease (OncoSENS), but the SENS claim that nuclear DNA damage only matters for aging because of cancer has been challenged in the literature^[25] as well as by material in the article DNA damage theory of aging.

In November 2005, 28 biogerontologists published a statement of criticism in EMBO Reports, "Science fact and the SENS agenda: what can we reasonably expect from ageing research?,"^[26] arguing "each one of the specific proposals that comprise the SENS agenda is, at our present stage of ignorance, exceptionally optimistic,"^[26] and that some of the specific proposals "will take decades of hard work [to be medically integrated], if [they] ever prove to be useful."^[26] The researchers argue that while there is "a rationale for thinking that we might eventually learn how to postpone human illnesses to an important degree,"^[26] increased basic research, rather than the goal-directed approach of SENS, is presently the scientifically appropriate goal. This article was written in response to a July 2005 EMBO Reports article previously published by de Grey^[27] and a response from de Grey was published in the same November issue.^[28] De Grey summarizes these events in "The biogerontology research community's evolving view of SENS," published on the Methuselah Foundation website.^[29]

In 2012, Colin Blakemore criticised Aubrey de Grey, but not SENS specifically, in a debate hosted at the Oxford University Scientific Society.^{[citation needed]}

More recently, biogerontologist Marios Kyriazis has sharply criticised the clinical applicability of SENS^[30][31] claiming that such therapies, even if developed in the laboratory, would be practically unusable by the general public.^[32] De Grey responded to one such criticism.^[33]

Technology Review controversy

In February 2005, Technology Review, which is owned by the Massachusetts Institute of Technology, published an article by Sherwin Nuland, a Clinical Professor of Surgery at Yale University and the author of "How We Die",^[34] that drew a skeptical portrait of SENS, at the time de Grey was a computer associate in the Flybase Facility of the Department of Genetics at the University of Cambridge. The April 2005 issue of Technology Review contained a reply by Aubrey de Grey^[35] and numerous comments from readers.^[36]

During June 2005, David Gobel, CEO and Co-founder of Methuselah Foundation offered Technology Review $20,000 to fund a prize competition to publicly clarify the viability of the SENS approach. In July 2005, Pontin announced a $20,000 prize, funded 50/50 by Methuselah Foundation and MIT Technology Review, open to any molecular biologist, with a record of publication in biogerontology, who could prove that the alleged benefits of SENS were "so wrong that it is unworthy of learned debate."^[37] Technology Review received five submissions to its Challenge. In March 2006, Technology Review announced that it had chosen a panel of judges for the Challenge: Rodney Brooks, Anita Goel, Nathan Myhrvold, Vikram Sheel Kumar, and Craig Venter.^[38] Three of the five submissions met the terms of the prize competition. They were published by Technology Review on June 9, 2006. Accompanying the three submissions were rebuttals by de Grey, and counter-responses to de Grey's rebuttals. On July 11, 2006, Technology Review published the results of the SENS Challenge.^[7][39]

In the end, no one won the $20,000 prize. The judges felt that no submission met the criterion of the challenge and discredited SENS, although they unanimously agreed that one submission, by Preston Estep and his colleagues, was the most eloquent. Craig Venter succinctly expressed the prevailing opinion: "Estep et al. ... have not demonstrated that SENS is unworthy of discussion, but the proponents of SENS have not made a compelling case for it."^[7] Summarizing the judges' deliberations, Pontin wrote that SENS is "highly speculative" and that many of its proposals could not be reproduced with the scientific technology of that period.^{[clarification needed]} Myhrvold described SENS as belonging to a kind of "antechamber of science" where they wait until technology and scientific knowledge advance to the point where it can be tested.^[7][8] In a letter of dissent dated July 11, 2006 in Technology Review, Estep et al. criticized the ruling of the judges.

Social and economic implications

Of the roughly 150,000 people who die each day across the globe, about two thirds—100,000 per day—die of age-related causes.^[40] In industrialized nations, the proportion is much higher, reaching 90%.^[40]

De Grey and other scientists in the general field have argued that the costs of a rapidly growing aging population will increase to the degree that the costs of an accelerated pace of aging research are easy to justify in terms of future costs avoided. Olshansky et al. 2006 argue, for example, that the total economic cost of Alzheimer's disease in the US alone will increase from $80–100 billion today to more than $1 trillion in 2050.^[41] "Consider what is likely to happen if we don't [invest further in aging research]. Take, for instance, the impact of just one age-related disorder, Alzheimer disease (AD). For no other reason than the inevitable shifting demographics, the number of Americans stricken with AD will rise from 4 million today to as many as 16 million by midcentury. This means that more people in the United States will have AD by 2050 than the entire current population of the Netherlands. Globally, AD prevalence is expected to rise to 45 million by 2050, with three of every four patients with AD living in a developing nation. The US economic toll is currently $80–$100 billion, but by 2050 more than $1 trillion will be spent annually on AD and related dementias. The impact of this single disease will be catastrophic, and this is just one example."^[41]

SENS meetings

There have been four SENS roundtables and six SENS conferences held.^[42][43] The first SENS roundtable was held in Oakland, California on October, 2000,^[44] and the last SENS roundtable was held in Bethesda, Maryland on July, 2004.^[45]

On March 30–31, 2007 a North American SENS symposium was held in Edmonton, Alberta, Canada as the Edmonton Aging Symposium.^[46][47] Another SENS-related conference ("Understanding Aging") was held at UCLA in Los Angeles, California on June 27–29, 2008^[48]

Six SENS conferences have been held at Queens' College, Cambridge in England. All the conferences were organized by de Grey and all featured world-class researchers in the field of biogerontology.

• The first SENS conference was held in September 2003 as the 10th Congress of the International Association of Biomedical Gerontology^[49] with the proceedings published in the Annals of the New York Academy of Sciences.^[50]
• The second SENS conference was held in September 2005 and was simply called Strategies for Engineered Negligible Senescence (SENS), Second Conference^[51] with the proceedings published in Rejuvenation Research.
• The third SENS conference was held in September, 2007.^[52]
• The fourth SENS conference was held September 3–7, 2009.
• The fifth was held August 31 – September 4, 2011, like the first four, it was at Queens' College, Cambridge in England, organized by de Grey.^[53][54] Videos of the presentations are available.
• The sixth SENS conference (SENS6) was held from September 3–7, 2013.

Another meeting was held in August 2014 in Santa Clara, California.^[43]

SENS Research Foundation

The SENS Research Foundation is a non-profit organization co-founded by Michael Kope, Aubrey de Grey, Jeff Hall, Sarah Marr and Kevin Perrott, which is based in California, United States. Its activities include SENS-based research programs and public relations work for the acceptance of and interest in related research.
Before March 2009, the SENS research programme was mainly pursued by the Methuselah Foundation, co-founded by Aubrey de Grey and David Gobel. The Methuselah Foundation is most notable for establishing the Methuselah Mouse Prize, a monetary prize awarded to researchers who extend the lifespan of mice to unprecedented lengths.^[55]

For 2013, The SENS Research Foundation has a research budget of approximately $4 million annually, half of it funded by a personal contribution of $13 million of Aubrey de Grey's^[56] own wealth, and the other half coming from external donors, with the largest external donor being Peter Thiel, and another Internet entrepreneur Jason Hope,^[57] has recently begun to contribute comparable sums.

Physician

From Wikipedia, the free encyclopedia

Physician

The Doctor by Luke Fildes (detail)[1][2]
Occupation
Names	Physician, medical practitioner, medical doctor or simply doctor
Professional
Activity sectors	Medicine, health care
Description
Competencies	The ethics, art and science of medicine, analytical skills, critical thinking
Education required	MBBS, MD, DO
Fields of employment	Clinics, hospitals
Related jobs	General practitioner Family physician Surgeon Medical specialties Dentist Chiropractor Medicine Glossary of medicine

A physician, medical practitioner, medical doctor, or simply doctor is a professional who practises medicine, which is concerned with promoting, maintaining, or restoring health through the study, diagnosis, and treatment of disease, injury, and other physical and mental impairments. Physicians may focus their practice on certain disease categories, types of patients and methods of treatment—known as specialities—or they may assume responsibility for the provision of continuing and comprehensive medical care to individuals, families, and communities—known as general practice. Medical practice properly requires both a detailed knowledge of the academic disciplines (such as anatomy and physiology) underlying diseases and their treatment—the science of medicine—and also a decent competence in its applied practice—the art or craft of medicine.

Both the role of the physician and the meaning of the word itself vary around the world. Degrees and other qualifications vary widely, but there are some common elements, such as medical ethics requiring that physicians show consideration, compassion, and benevolence for their patients.

Modern meanings

The Italian Francesco Redi, considered to be the founder of experimental biology, he was the first to recognize and correctly describe details of many important parasites.^[4]

Specialist in internal medicine

Around the world the term physician refers to a specialist in internal medicine or one of its many sub-specialties (especially as opposed to a specialist in surgery). This meaning of physician conveys a sense of expertise in treatment by drugs or medications, rather than by the procedures of surgeons.^[5]

This term is at least nine hundred years old in English: physicians and surgeons were once members of separate professions, and traditionally were rivals. The Shorter Oxford English Dictionary, third edition, gives a Middle English quotation making this contrast, from as early as 1400: "O Lord, whi is it so greet difference betwixe a cirugian and a physician."^[6]

Henry VIII granted a charter to the London Royal College of Physicians in 1518. It was not until 1540 that he granted the Company of Barber-Surgeons (ancestor of the Royal College of Surgeons) its separate charter. In the same year, the English monarch established the Regius Professorship of Physic at the University of Cambridge.^[7] Newer universities would probably describe such an academic as a professor of internal medicine. Hence, in the 16th century, physic meant roughly what internal medicine does now.

Currently, a specialist physician in the United States may be described as an internist. Another term, hospitalist, was introduced in 1996,^[8] to describe US specialists in internal medicine who work largely or exclusively in hospitals. Such 'hospitalists' now make up about 19% of all US general internists,^[9] who are often called general physicians in Commonwealth countries.

This original use, as distinct from surgeon, is common in most of the world including the United Kingdom and other Commonwealth countries (such as Australia, Bangladesh, India, New Zealand, Pakistan, South Africa, Sri Lanka, Zimbabwe), as well as in places as diverse as Brazil, Hong Kong, Indonesia, Japan, Ireland, and Taiwan. In such places, the more general English terms doctor or medical practitioner are prevalent, describing any practitioner of medicine (whom an American would likely call a physician, in the broad sense).^[10] In Commonwealth countries, specialist pediatricians and geriatricians are also described as specialist physicians who have sub-specialized by age of patient rather than by organ system.

Physician and surgeon

Around the world, the combined term "physician and surgeon" is used to describe either a general practitioner or any medical practitioner irrespective of specialty.^[5][6] This usage still shows the original meaning of physician and preserves the old difference between a physician, as a practitioner of physic, and a surgeon. The term may be used by state medical boards in the United States of America, and by equivalent bodies in provinces of Canada, to describe any medical practitioner.

North America

Elizabeth Blackwell, the first female physician to receive a medical degree in the United States

In modern English, the term physician is used in two main ways, with relatively broad and narrow meanings respectively. This is the result of history and is often confusing. These meanings and variations are explained below.

In the United States and Canada, the term physician describes all medical practitioners holding a professional medical degree. The American Medical Association, established in 1847, as well as the American Osteopathic Association, founded in 1897, both currently use the term physician to describe members. However, the American College of Physicians, established in 1915, does not: its title uses physician in its original sense.

American physicians

The vast majority of physicians trained in the United States have a Doctor of Medicine degree, and use the initials M.D. A smaller number attend Osteopathic schools and have a Doctor of Osteopathic Medicine degree and use the initials D.O.^[11] After completion of medical school, physicians complete a residency in the specialty in which they will practice. Subspecialties require the completion of a fellowship after residency.

All boards of certification now require that physicians demonstrate, by examination, continuing mastery of the core knowledge and skills for a chosen specialty. Recertification varies by particular specialty between every seven and every ten years.

Podiatric physicians

Also in the United States, the American Podiatric Medical Association (APMA) defines podiatrists as physicians and surgeons that fall under the department of surgery in hospitals.^[12] They undergo training with the Doctor of Podiatric Medicine (DPM) degree.^[13] This degree is also available at one Canadian university, namely the Université du Québec à Trois-Rivières. Students are typically required to complete an internship in New York prior to the obtention of their professional degree.

Shortage

Many countries in the developing world have the problem of too few physicians.^[14] A shortage of doctors can lead to diseases spreading out of control as seen in the Ebola virus epidemic in West Africa. In 2015, the Association of American Medical Colleges warned that the US will face a doctor shortage of as many as 90,000 by 2025.^[15]

Social role and world view

Biomedicine

Within Western culture and over recent centuries, medicine has become increasingly based on scientific reductionism and materialism. This style of medicine is now dominant throughout the industrialized world, and is often termed biomedicine by medical anthropologists.^[16] Biomedicine "formulates the human body and disease in a culturally distinctive pattern",^[17] and is a world view learnt by medical students. Within this tradition, the medical model is a term for the complete "set of procedures in which all doctors are trained" (R. D. Laing, 1972),^[18] including mental attitudes. A particularly clear expression of this world view, currently dominant among conventional physicians, is evidence-based medicine. Within conventional medicine, most physicians still pay heed to their ancient traditions:

The critical sense and sceptical attitude of the citation of medicine from the shackles of priestcraft and of caste; secondly, the conception of medicine as an art based on accurate observation, and as a science, an integral part of the science of man and of nature; thirdly, the high moral ideals, expressed in that most "memorable of human documents" (Gomperz), the Hippocratic oath; and fourthly, the conception and realization of medicine as the profession of a cultivated gentleman.

— Sir William Osler, Chauvanism in Medicine (1902)^[19]

In this Western tradition, physicians are considered to be members of a learned profession, and enjoy high social status, often combined with expectations of a high and stable income and job security. However, medical practitioners often work long and inflexible hours, with shifts at unsociable times. Their high status is partly from their extensive training requirements, and also because of their occupation's special ethical and legal duties. The term traditionally used by physicians to describe a person seeking their help is the word patient (although one who visits a physician for a routine check-up may also be so described). This word patient is an ancient reminder of medical duty, as it originally meant 'one who suffers'. The English noun comes from the Latin word patiens, the present participle of the deponent verb, patior, meaning 'I am suffering,' and akin to the Greek verb πάσχειν (= paskhein, to suffer) and its cognate noun πάθος (= pathos).^[6][20]

Physicians in the original, narrow sense (specialist physicians or internists, see above) are commonly members or fellows of professional organizations, such as the American College of Physicians or the Royal College of Physicians in the United Kingdom, and such hard-won membership is itself a mark of status.^{[citation needed]}

Alternative medicine

While contemporary biomedicine has distanced itself from its ancient roots in religion and magic, many forms of traditional medicine^[21] and alternative medicine continue to espouse vitalism in various guises: 'As long as life had its own secret properties, it was possible to have sciences and medicines based on those properties' (Grossinger 1980).^[22] The US National Center for Complementary and Alternative Medicine (NCCAM) classifies CAM therapies into five categories or domains, including:^[23] alternative medical systems, or complete systems of therapy and practice; mind-body interventions, or techniques designed to facilitate the mind's effect on bodily functions and symptoms; biologically based systems including herbalism; and manipulative and body-based methods such as chiropractic and massage therapy.

In considering these alternate traditions that differ from biomedicine (see above), medical anthropologists emphasize that all ways of thinking about health and disease have a significant cultural content, including conventional western medicine.

Ayurveda, Unani medicine and homeopathy are popular types of alternative medicine. They are included in national system of medicines in countries such as India. In general, the practitioners of these medicine in these countries are referred to as Ved, Hakim and homeopathic doctor/homeopath/homeopathic physician, respectively.

Physicians' own health

Some commentators have argued that physicians have duties to serve as role models for the general public in matters of health, for example by not smoking cigarettes.^[26] Indeed, in most western nations relatively few physicians smoke, and their professional knowledge does appear to have a beneficial effect on their health and lifestyle. According to a study of male physicians,^[27] life expectancy is slightly higher for physicians (73.0 years for white and 68.7 for black) than lawyers or many other highly educated professionals. Causes of death less likely in physicians than the general population include respiratory disease (including pneumonia, pneumoconioses, COPD, but excluding emphysema and other chronic airway obstruction), alcohol-related deaths, rectosigmoidal and anal cancers, and bacterial diseases.^[27]

Physicians do experience exposure to occupational hazards, and there is a well-known aphorism that "doctors make the worst patients".^[28] Causes of death that are shown to be higher in the physician population include suicide among doctors and self-inflicted injury, drug-related causes, traffic accidents, and cerebrovascular and ischaemic heart disease.^[27]

Education and training

Medical education and career pathways for doctors vary considerably across the world.

All medical practitioners

In all developed countries, entry-level medical education programs are tertiary-level courses, undertaken at a medical school attached to a university. Depending on jurisdiction and university, entry may follow directly from secondary school or require pre-requisite undergraduate education. The former commonly takes five or six years to complete. Programs that require previous undergraduate education (typically a three- or four-year degree, often in Science) are usually four or five years in length. Hence, gaining a basic medical degree may typically take from five to eight years, depending on jurisdiction and university.

Following completion of entry-level training, newly graduated medical practitioners are often required to undertake a period of supervised practice before full registration is granted, typically one or two years. This may be referred to as an "internship", as the "foundation" years in the UK, or as "conditional registration". Some jurisdictions, including the United States, require residencies for practice.

Medical practitioners hold a medical degree specific to the university from which they graduated. This degree qualifies the medical practitioner to become licensed or registered under the laws of that particular country, and sometimes of several countries, subject to requirements for internship or conditional registration.

Specialists in internal medicine

Specialty training is begun immediately following completion of entry-level training, or even before. In other jurisdictions, junior medical doctors must undertake generalist (un-streamed) training for one or more years before commencing specialization. Hence, depending on jurisdiction, a specialist physician (internist) often does not achieve recognition as a specialist until twelve or more years after commencing basic medical training—five to eight years at university to obtain a basic medical qualification, and up to another nine years to become a specialist.

Regulation

In most jurisdictions, physicians (in either sense of the word) need government permission to practice. Such permission is intended to promote public safety, and often to protect the public purse, as medical care is commonly subsidized by national governments.

In some jurisdictions (e.g., Singapore), it is common for physicians to inflate their qualifications with the title "Dr" in correspondence or namecards, even if their qualifications are limited to a basic (e.g., bachelor level) degree. In other countries (e.g., Germany), only physicians holding an academic doctorate may call themselves doctor – on the other hand, the European Research Council has decided that the German medical doctorate does not meet the international standards of a PhD research degree.^[29][30]

All medical practitioners

Among the English-speaking countries, this process is known either as licensure as in the United States, or as registration in the United Kingdom, other Commonwealth countries, and Ireland. Synonyms in use elsewhere include colegiación in Spain, ishi menkyo in Japan, autorisasjon in Norway, Approbation in Germany, and "άδεια εργασίας" in Greece. In France, Italy and Portugal, civilian physicians must be members of the Order of Physicians to practice medicine.

In some countries, including the United Kingdom and Ireland, the profession largely regulates itself, with the government affirming the regulating body's authority. The best known example of this is probably the General Medical Council of Britain. In all countries, the regulating authorities will revoke permission to practice in cases of malpractice or serious misconduct.

In the large English-speaking federations (United States, Canada, Australia), the licensing or registration of medical practitioners is done at a state or provincial level or nationally as in New Zealand. Australian states usually have a "Medical Board," which has now been replaced by the Australian Health Practitioner Regulatory Authority (AHPRA) in most states, while Canadian provinces usually have a "College of Physicians and Surgeons." All American states have an agency that is usually called the "Medical Board", although there are alternate names such as "Board of Medicine," "Board of Medical Examiners", "Board of Medical Licensure", "Board of Healing Arts" or some other variation.^[31] After graduating from a first-professional school, physicians who wish to practice in the U.S. usually take standardized exams, such as the USMLE for MDs).

Specialists in internal medicine

Most countries have some method of officially recognizing specialist qualifications in all branches of medicine, including internal medicine. Sometimes, this aims to promote public safety by restricting the use of hazardous treatments. Other reasons for regulating specialists may include standardization of recognition for hospital employment and restriction on which practitioners are entitled to receive higher insurance payments for specialist services.

Performance and professionalism supervision

The issue of medical errors, drug abuse, and other issues in physician professional behavior received significant attention across the world,^[32] in particular following a critical 2000 report^[33] which "arguably launched" the patient-safety movement.^[34] In the U.S., as of 2006 there were few organizations that systematically monitored performance. In the U.S. only the Department of Veterans Affairs randomly drug tests, in contrast to drug testing practices for other professions that have a major impact on public welfare. Licensing boards at the U.S. state level depend upon continuing education to maintain competence.^[35] Through the utilization of the National Practitioner Data Bank, Federation of State Medical Boards Disciplinary Report, and American Medical Association Physician Profile Service, the 67 State Medical Boards (MD/DO) continually self-report any Adverse/Disciplinary Actions taken against a licensed Physician in order that the other Medical Boards in which the Physician holds or is applying for a medical license will be properly notified so that corrective, reciprocal action can be taken against the offending physician.^[36] In Europe, as of 2009 the health systems are governed according to various national laws, and can also vary according to regional differences similar to the United States.^[37]

Related occupations and divisions of labor

Chiropractors

Chiropractors use the physician title in some countries. In the United States, practitioners with a Doctor of Chiropractic (DC) have been added to the list of recognized physicians by the Joint Commission on Accreditation of Healthcare Organizations.^[38] This change does not affect or alter any health care practitioner’s license or scope of practice.^[39] Some medical organizations have criticized the addition of chiropractic to the definition of physician.^[39]

In Switzerland, students since 2008 have the option of studying in the University of Zurich medical school earning a Bachelor of Medicine (with a focus on chiropractic) and a Masters in Chiropractic Medicine.^[40][41][42] By attending medical school, they become "physicians" in the more traditional sense. Swiss chiropractors have been found to treat conditions in a similar way to their international counterparts while enjoying a greater number of medical specialist referrals.^[43]

Nurse practitioners

Nurse practitioners (NPs) in the United States are advanced practice registered nurses holding a post-graduate degree such as a Doctor of Nursing Practice.^[44] In Canada, nurse practitioners typically have a Master of nursing degree as well as substantial experience they have accumulated throughout the years. Nurse practitioners are not physicians but may practice alongside physicians in a variety of fields. Nurse practitioners are educated in nursing theory and nursing practice. The scope of practice for a nurse practitioner in the United States is defined by regulatory boards of nursing, as opposed to boards of medicine that regulate physicians.