Biological immortality

Biological immortality (sometimes referred to as bio-indefinite mortality) is a state in which the rate of mortality from senescence is stable or decreasing, thus decoupling it from chronological age. Various unicellular and multicellular species, including some vertebrates, achieve this state either throughout their existence or after living long enough. A biologically immortal living being can still die from means other than senescence, such as through injury, disease, or lack of available resources.

This definition of immortality has been challenged in the Handbook of the Biology of Aging,[1] because the increase in rate of mortality as a function of chronological age may be negligible at extremely old ages, an idea referred to as the late-life mortality plateau. The rate of mortality may cease to increase in old age, but in most cases that rate is typically very high.[2] As a hypothetical example, there is a 50% chance of a human surviving another year at age 110 or greater.

The term is also used by biologists to describe cells that are not subject to the Hayflick limit on how many times they can divide.

Cell lines

Biologists chose the word "immortal" to designate cells that are not subject to the Hayflick limit, the point at which cells can no longer divide due to DNA damage or shortened telomeres. Prior to Leonard Hayflick's theory, Alexis Carrel hypothesized that all normal somatic cells were immortal.[3]

The term "immortalization" was first applied to cancer cells that expressed the telomere-lengthening enzyme telomerase, and thereby avoided apoptosis—i.e. cell death caused by intracellular mechanisms. Among the most commonly used cell lines are HeLa and Jurkat, both of which are immortalized cancer cell lines. HeLa cells originated from a sample of cervical cancer taken from Henrietta Lacks in 1951.[4] These cells have been and still are widely used in biological research such as creation of the polio vaccine,[5] sex hormone steroid research,[6] and cell metabolism.[7] Normal stem cells and germ cells can also be said to be immortal (when humans refer to the cell line).

Immortal cell lines of cancer cells can be created by induction of oncogenes or loss of tumor suppressor genes. One way to induce immortality is through viral-mediated induction of the large T‑antigen,[8] commonly introduced through simian virus 40 (SV-40).[9]

Organisms

According to the Animal Aging and Longevity Database, the list of organisms with negligible aging (along with estimated longevity in the wild) includes:[10]

In 2018, scientists working for Calico, a company owned by Alphabet, published a paper in the journal eLife which presents possible evidence that Heterocephalus glaber (Naked mole rat) do not face increased mortality risk due to aging.[11][12][13]

Bacteria and some yeast

Many unicellular organisms age: as time passes, they divide more slowly and ultimately die. Asymmetrically dividing bacteria and yeast also age. However, symmetrically dividing bacteria and yeast can be biologically immortal under ideal growing conditions.[14] In these conditions, when a cell splits symmetrically to produce two daughter cells, the process of cell division can restore the cell to a youthful state. However, if the parent asymmetrically buds off a daughter only the daughter is reset to the youthful state—the parent isn't restored and will go on to age and die. In a similar manner stem cells and gametes can be regarded as "immortal".

Hydra

Hydras (8)
Hydra

Hydras are a genus of the Cnidaria phylum. All cnidarians can regenerate, allowing them to recover from injury and to reproduce asexually. Hydras are simple, freshwater animals possessing radial symmetry and no post-mitotic cells. All hydra cells continually divide. It has been suggested that hydras do not undergo senescence, and, as such, are biologically immortal. In a four-year study, 3 cohorts of hydra did not show an increase in mortality with age. It is possible that these animals live much longer, considering that they reach maturity in 5 to 10 days.[15] However, this does not explain how hydras are consequently able to maintain telomere lengths.

Jellyfish

Turritopsis dohrnii, or Turritopsis nutricula, is a small (5 millimeters (0.20 in)) species of jellyfish that uses transdifferentiation to replenish cells after sexual reproduction. This cycle can repeat indefinitely, potentially rendering it biologically immortal. This organism originated in the Caribbean sea, but has now spread around the world. Similar cases include hydrozoan Laodicea undulata[16] and scyphozoan Aurelia sp.1.[17]

Lobsters

Research suggests that lobsters may not slow down, weaken, or lose fertility with age, and that older lobsters may be more fertile than younger lobsters. This does not however make them immortal in the traditional sense, as they are significantly more likely to die at a shell moult the older they get (as detailed below).

Their longevity may be due to telomerase, an enzyme that repairs long repetitive sections of DNA sequences at the ends of chromosomes, referred to as telomeres. Telomerase is expressed by most vertebrates during embryonic stages but is generally absent from adult stages of life.[18] However, unlike vertebrates, lobsters express telomerase as adults through most tissue, which has been suggested to be related to their longevity.[19][20][21] Contrary to popular belief, lobsters are not immortal. Lobsters grow by moulting which requires a lot of energy, and the larger the shell the more energy is required.[22] Eventually, the lobster will die from exhaustion during a moult. Older lobsters are also known to stop moulting, which means that the shell will eventually become damaged, infected, or fall apart and they die.[23] The European lobster has an average life span of 31 years for males and 54 years for females.

Planarian flatworms

Polycelis felina
Polycelis felina, a freshwater planarian

Planarian flatworms have both sexually and asexually reproducing types. Studies on genus Schmidtea mediterranea suggest these planarians appear to regenerate (i.e. heal) indefinitely, and asexual individuals have an "apparently limitless [telomere] regenerative capacity fueled by a population of highly proliferative adult stem cells". "Both asexual and sexual animals display age-related decline in telomere length; however, asexual animals are able to maintain telomere lengths somatically (i.e. during reproduction by fission or when regeneration is induced by amputation), whereas sexual animals restore telomeres by extension during sexual reproduction or during embryogenesis like other sexual species. Homeostatic telomerase activity observed in both asexual and sexual animals is not sufficient to maintain telomere length, whereas the increased activity in regenerating asexuals is sufficient to renew telomere length... "[24]

Lifespan: For sexually reproducing planaria: "the lifespan of individual planarian can be as long as 3 years, likely due to the ability of neoblasts to constantly replace aging cells". Whereas for asexually reproducing planaria: "individual animals in clonal lines of some planarian species replicating by fission have been maintained for over 15 years".[25] They are "literally immortal."[26]

Attempts to engineer biological immortality in humans

Although the premise that biological aging can be halted or reversed by foreseeable technology remains controversial,[27] research into developing possible therapeutic interventions is underway.[28] Among the principal drivers of international collaboration in such research is the SENS Research Foundation, a non-profit organization that advocates a number of what it claims are plausible research pathways that might lead to engineered negligible senescence in humans.[29][30]

In 2015, Elizabeth Parrish, CEO of BioViva, treated herself using gene therapy with the goal of not just halting, but reversing aging.[31] She has since reported feeling more energetic, and no obvious negative side effects have been noticed.[32]

For several decades,[33] researchers have also pursued various forms of suspended animation as a means by which to indefinitely extend mammalian lifespan. Some scientists have voiced support[34] for the feasibility of the cryopreservation of humans, known as cryonics. Cryonics is predicated on the concept that some people considered clinically dead by today's medicolegal standards are not actually dead according to information-theoretic death and can, in principle, be resuscitated given sufficient technological advances.[35] The goal of current cryonics procedures is tissue vitrification, a technique first used to reversibly cryopreserve a viable whole organ in 2005.[36][37]

Similar proposals involving suspended animation include chemical brain preservation. The non-profit Brain Preservation Foundation offers a cash prize valued at over $100,000 for demonstrations of techniques that would allow for high-fidelity, long-term storage of a mammalian brain.[38]

In 2016, scientists at the Buck Institute for Research on Aging and the Mayo Clinic employed genetic and pharmacological approaches to ablate pro-aging senescent cells, extending healthy lifespan of mice by over 25%. The startup Unity Biotechnology is further developing this strategy in human clinical trials.[39]

In early 2017, Harvard scientists headed by biologist David Sinclair announced they have tested a metabolic precursor that increases NAD+ levels in mice and have successfully reversed the cellular aging process and can protect the DNA from future damage. "The old mouse and young mouse cells are indistinguishable", David was quoted. Human trials are to begin shortly in what the team expect is 6 months at Brigham and Women's Hospital, in Boston.[40]

Criticism

To achieve the more limited goal of halting the increase in mortality rate with age, a solution must be found to the fact that any intervention to remove senescent cells that creates competition among cells will increase age-related mortality from cancer.[41]

Immortalism and immortality as a movement

In 2012 in Russia, and then in the United States, Israel, and the Netherlands, pro-immortality transhumanist political parties were launched.[42] They aim to provide political support to anti-aging and radical life extension research and technologies and want to ensure the fastest possible—and at the same time, the least disruptive—societal transition to radical life extension, life without aging, and ultimately, immortality. They aim to make it possible to provide access to such technologies to the majority of people alive today.[43]

Future medicine, life extension and "swallowing the doctor"

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 molecular 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.[44] 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.[45]

See also

References

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Bibliography

  • James L. Halperin. The First Immortal, Del Rey, 1998. ISBN 0-345-42092-6
  • Robert Ettinger. The Prospect of Immortality, Ria University Press, 2005. ISBN 0-9743472-3-X
  • Dr. R. Michael Perry. Forever For All: Moral Philosophy, Cryonics, and the Scientific Prospects for Immortality, Universal Publishers, 2001. ISBN 1-58112-724-3
  • Martinez, D.E. (1998) "Mortality patterns suggest lack of senescence in hydra." Experimental Gerontology 1998 May;33(3):217–225. Full text.
  • Rose, Michael; Rauser, Casandra L.; Mueller, Laurence D. (Spring 2011). Does Aging Stop?. Oxford University Press.

External links

2036

2036 (MMXXXVI)

will be a leap year starting on Tuesday of the Gregorian calendar, the 2036th year of the Common Era (CE) and Anno Domini (AD) designations, the 36th year of the 3rd millennium, the 36th year of the 21st century, and the 7th year of the 2030s decade.

Anti-aging movement

The anti-aging movement is a social movement devoted to eliminating or reversing aging, or reducing the effects of it. A substantial portion of the attention of the movement is on the possibilities for life extension, but there is also interest in techniques such as cosmetic surgery which ameliorate the effects of aging rather than delay or defeat it.Two popular proponents of the anti-aging movement include Ray Kurzweil, who says humanity can defeat aging through the advance of technology, and Aubrey De Grey, who says that the human body is a very complicated machine and thus, can be repaired indefinitely. Other scientists and significant contributors to the movement include molecular biologists, geneticists, and biomedical gerontologists such as Gary Ruvkun, Cynthia Kenyon, and Arthur D. Levinson. However, figures in the gerontology community in 2003 tried to distance their research from the perceived pseudoscience of the movement.

Death

Death is the inevitable, permanent cessation of all biological functions that sustain a living organism. Phenomena which commonly bring about death include aging, predation, malnutrition, disease, suicide, homicide, starvation, dehydration, and accidents or major trauma resulting in terminal injury. In most cases, bodies of living organisms begin to decompose shortly after death.Death – particularly the death of humans – has commonly been considered a sad or unpleasant occasion, due to the affection for the being that has died and the termination of social and familial bonds with the deceased. Other concerns include fear of death, necrophobia, anxiety, sorrow, grief, emotional pain, depression, sympathy, compassion, solitude, or saudade. Many cultures and religions have the idea of an afterlife, and also hold the idea of reward or judgement and punishment for past sin.

Gerontology Research Group

The Gerontology Research Group (GRG) is a global group of researchers in various fields that verifies and tracks supercentenarians, or people who are at least 110 years old in a list of the verified oldest people. The group also aims to further gerontology research with a goal of reversing or slowing aging.

Immortality

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 and debate.

John Sperling

John Glen Sperling (January 9, 1921 – August 22, 2014) was an American businessman who is credited with having led the contemporary for-profit education movement in the United States. The fortune he amassed was based on his founding of the for-profit University of Phoenix for working adults in 1976, which is now part of the publicly traded Apollo Group. For ventures ranging from pet cloning to green energy, he has widely been described as an "eccentric" self-made man by the Washington Post and other media.

Laura Deming

Laura Deming is a venture capitalist. Her work focuses on life extension, and using biological research to reduce or reverse the effects of aging.

List of civilisations in the Culture series

Various fictional societies are depicted in the Culture series of Iain M. Banks.

List of longest-living organisms

This is a list of the longest-living organisms; that is, the individual member(s) (or in some instances, clones) of a species. This may be, for a given species:

Oldest known individuals that are currently alive, with verified ages

Verified Record holders, such as the longest-lived human, Jeanne Calment, or the longest-lived domestic cat, Creme Puff (1967-2005).Ordinarily, this does not consider the age of the species itself, comparing species by the range of age-span of their individuals, or the time between first appearance (speciation) and extinction of the species.

List of science fiction themes

The following is a list of articles about recurring themes in science fiction.

Marios Kyriazis

Marios Kyriazis (Greek: Μάριος Κυριαζής) (born 11 March 1956) is a medical doctor and gerontologist. He is known for work, publications and involvement with life extension.Applying the concept of hormesis on anti-ageing medicine, Kyriazis controversially suggested that leading a stressful, irregular and constantly stimulating lifestyle may be a way of reducing the impact of age-related dysfunction.

Negligible senescence

Negligible senescence is a term coined by biogerontologist Caleb Finch to denote organisms that do not exhibit evidence of senescence (biological aging), such as measurable reductions in their reproductive capability, measurable functional decline, or rising death rates with age.There are many species where scientists have seen no increase in mortality after maturity. This may mean that the lifespan of the organism is so long that researchers' subjects have not yet lived up to the time when a measure of the species' longevity can be made. Turtles, for example, were once thought to lack senescence, but more extensive observations have found evidence of decreasing fitness with age.Study of negligibly senescent animals may provide clues that lead to better understanding of the aging process and influence theories of aging. The phenomenon of negligible senescence in some animals is a traditional argument for attempting to achieve similar negligible senescence in humans by technological means.

There is "non-senescence" in the genus Hydra.There are also organisms that exhibit negative senescence, whereby mortality chronologically decreases as the organism ages, for all or part of the life cycle, in disagreement with the Gompertz–Makeham law of mortality (see also Late-life mortality deceleration). Furthermore, there are species that have been observed to regress to a larval state and regrow into adults multiple times, such as Turritopsis dohrnii.Recent studies have indicated a connection between phenomena related to negligible senescence and the general stability of an organism's genome, specifically transcription processes, over its lifetime.

New England Centenarian Study

The New England Centenarian Study is a study of persons aged 100 and over (centenarians) in the Boston area. It is one of the oldest, largest and most prestigious studies of its kind in the world.The study began in 1994 and was originally focused on research into Alzheimer's. However, it soon became apparent that most centenarians did not have Alzheimer's even though other forms of dementia were common. So it transitioned into finding out why some people can live to 100 and others don't. Some findings included that centenarians had natural advantages, including large blood-platelet size. Studies for genes managed to identify only one major gene associated with longevity.

Researchers are now investigating more detailed genetic analysis including epigenetics. Formerly located at Harvard University, the Study is now located at Boston University and led by Dr. Tom Perls.

In 2006, an offshoot, the New England Supercentenarian Study, was begun.

A study of gene tests of hundreds of centenarians reported in July 2010 that genetics plays an extremely important role in deciding who reaches that age. Centenarians rarely develop diseases of aging, and are more likely to bounce back from diseases. Led by Perls, the study was funded by the National Institute on Aging's Division of Geriatrics and Clinical Gerontology.

Outline of life extension

The following outline is provided as an overview of and topical guide to life extension:

Life extension – study of slowing down or reversing the processes of aging to extend both the maximum and average lifespan. Also known as anti-aging medicine, experimental gerontology, and biomedical gerontology.

Rejuvenation

Rejuvenation is a medical discipline focused on the practical reversal of the aging process.Rejuvenation is distinct from life extension. Life extension strategies often study the causes of aging and try to oppose those causes in order to slow aging. Rejuvenation is the reversal of aging and thus requires a different strategy, namely repair of the damage that is associated with aging or replacement of damaged tissue with new tissue. Rejuvenation can be a means of life extension, but most life extension strategies do not involve rejuvenation.

Sirtuin

Sirtuins are a class of proteins that possess either mono-ADP-ribosyltransferase, or deacylase activity, including deacetylase, desuccinylase, demalonylase, demyristoylase and depalmitoylase activity. The name Sir2 comes from the yeast gene 'silent mating-type information regulation 2', the gene responsible for cellular regulation in yeast.

Sirtuins have been implicated in influencing a wide range of cellular processes like aging, transcription, apoptosis, inflammation and stress resistance, as well as energy efficiency and alertness during low-calorie situations. Sirtuins can also control circadian clocks and mitochondrial biogenesis.

Yeast Sir2 and some, but not all, sirtuins are protein deacetylases. Unlike other known protein deacetylases, which simply hydrolyze acetyl-lysine residues, the sirtuin-mediated deacetylation reaction couples lysine deacetylation to NAD hydrolysis. This hydrolysis yields O-acetyl-ADP-ribose, the deacetylated substrate and nicotinamide, which is an inhibitor of sirtuin activity itself. The dependence of sirtuins on NAD links their enzymatic activity directly to the energy status of the cell via the cellular NAD:NADH ratio, the absolute levels of NAD, NADH or nicotinamide or a combination of these variables.

Sirtuins that deacetylate histones are structurally and mechanistically distinct from other classes of histone deacetylases (classes I, IIA, IIB and IV), which have a different protein fold and use Zn2+ as a cofactor.

Turritopsis dohrnii

Turritopsis dohrnii, the immortal jellyfish, is a species of small, biologically immortal jellyfish found in the Mediterranean Sea and in the waters of Japan. It is one of the few known cases of animals capable of reverting completely to a sexually immature, colonial stage after having reached sexual maturity as a solitary individual. Others include the jellyfish Laodicea undulata and Aurelia sp.1.Like most other hydrozoans, T. dohrnii begin their life as tiny, free-swimming larvae known as planula. As a planula settles down, it gives rise to a colony of polyps that are attached to the sea-floor. All the polyps and jellyfish arising from a single planula are genetically identical clones. The polyps form into an extensively branched form, which is not commonly seen in most jellyfish. Jellyfish, also known as medusae, then bud off these polyps and continue their life in a free-swimming form, eventually becoming sexually mature. When sexually mature they have been known to prey on other jellyfish species at a rapid pace. If a T. dohrnii jellyfish is exposed to environmental stress or physical assault, or is sick or old, it can revert to the polyp stage, forming a new polyp colony. It does this through the cell development process of transdifferentiation, which alters the differentiated state of the cells and transforms them into new types of cells.

Theoretically, this process can go on indefinitely, effectively rendering the jellyfish biologically immortal, although in practice individuals can still die. In nature, most Turritopsis are likely to succumb to predation or disease in the medusa stage, without reverting to the polyp form.The capability of biological immortality with no maximum lifespan makes T. dohrnii an important target of basic biological, aging and pharmaceutical research.The "immortal jellyfish" was formerly classified as T. nutricula.

Ageing
Life extension
Immortality
Living and
notable centenarians
(over age 100)
Supercentenarians
(over age 110)
Miscellaneous records
Related

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