Posthuman or post-human is a concept originating in the fields of science fiction, futurology, contemporary art, and philosophy that means a person or entity that exists in a state beyond being human. The concept aims at addressing a variety of questions, including ethics
and justice, language and trans-species communication, social systems,
and the intellectual aspirations of interdisciplinarity.
Posthumanism is not to be confused with transhumanism
(the biotechnological enhancement of human beings) and narrow
definitions of the posthuman as the hoped-for transcendence of
materiality. The notion of the posthuman comes up both in posthumanism as well as
transhumanism, but it has a special meaning in each tradition.
In critical theory, the posthuman is a speculative being that represents or seeks to re-conceive the human. It is the object of posthumanist criticism, which critically questions humanism, a branch of humanist philosophy which claims that human nature is a universal state from which the human being emerges; human nature is autonomous, rational, capable of free will, and unified in itself as the apex of existence.
Thus, the posthuman position recognizes imperfectability and disunity
within oneself, and understands the world through heterogeneous perspectives while seeking to maintain intellectual rigor
and dedication to objective observations. Key to this posthuman
practice is the ability to fluidly change perspectives and manifest
oneself through different identities. The posthuman, for critical theorists of the subject, has an emergentontology rather than a stable one; in other words, the posthuman is not a singular, defined individual,
but rather one who can "become" or embody different identities and
understand the world from multiple, heterogeneous perspectives.
Approaches to posthumanism are not homogeneous, and have
often been very critical. The term itself is contested, with one of the
foremost authors associated with posthumanism, Manuel DeLanda, decrying the term as "very silly." Covering the ideas of, for example, Robert Pepperell's The Posthuman Condition, and Hayles'sHow We Became Posthuman under a single term is distinctly problematic due to these contradictions.
The posthuman is roughly synonymous with the "cyborg" of A Cyborg Manifesto by Donna Haraway. Haraway's conception of the cyborg is an ironic take on traditional conceptions of the cyborg that inverts the traditional trope of the cyborg whose presence questions the salient line between humans and robots. Haraway's cyborg is in many ways the "beta" version of the posthuman, as her cyborg theory prompted the issue to be taken up in critical theory. Following Haraway, Hayles, whose work grounds much of the critical posthuman discourse, asserts that liberal humanism—which separates the mind from the body
and thus portrays the body as a "shell" or vehicle for the mind—becomes
increasingly complicated in the late 20th and 21st centuries because information technology puts the human body
in question. Hayles maintains that we must be conscious of information
technology advancements while understanding information as
"disembodied," that is, something which cannot fundamentally replace the
human body but can only be incorporated into it and human life
practices.
Post-posthumanism and post-cyborg ethics
The idea of post-posthumanism (post-cyborgism) has recently been introduced. This body of work outlines the after-effects of long-term adaptation to
cyborg technologies and their subsequent removal, e.g., what happens
after 20 years of constantly wearing computer-mediating eyeglass
technologies and subsequently removing them, and of long-term adaptation
to virtual worlds followed by return to "reality." and the associated post-cyborg ethics (e.g. the ethics of forced removal of cyborg technologies by authorities, etc.).
Posthuman political and natural rights have been framed on a spectrum with animal rights and human rights. Posthumanism broadens the scope of what it means to be a valued life
form and to be treated as such (in contrast to certain life forms being
seen as less-than and being taken advantage of or killed off); it “calls
for a more inclusive definition of life, and a greater moral-ethical
response, and responsibility, to non-human life forms in the age of
species blurring and species mixing. … [I]t interrogates the hierarchic
ordering—and subsequently exploitation and even eradication—of life
forms.”
Hybrid interfaces: supersenses, cyborg systems, and hybrid bodies
Technology integrated into the human body changes how
individuals interact with the external world. Sensory activity is
mediated by technology, creating a new interface with the world. The
introduction of nanotechnologies and hybrid computing into the organism
alters the normal perception and cognition of things and the world. The
fusion of the human body with technology within the organism lays the
groundwork for the emergence of individuals endowed with new attributes
and capabilities. Human beings and the modification of their
psycho-physical characteristics become subjects of direct manipulation,
necessitating a reevaluation of the concept of humanity from various
humanistic, philosophical, and biological perspectives.
Human ability to incorporate inorganic elements of
technological nature into oneself can radically alter both inner and
outer appearance, transforming individuals into cyborgs. This new hybrid
form replaces the humanistic view of humanity and raises a series of
new philosophical questions concerning ethics and human nature.
Especially for new generations, the combination of carnal
body and virtual body can determine forms of identity hybridization and
possible negative effects on identity formation.
Further informationon an intermediate form between human and posthuman: Transhuman
According to transhumanist thinkers, a posthuman is a hypothetical future being "whose basic capacities so radically exceed those of present humans as to be no longer, unambiguously, human by our current standards." Posthumans primarily focus on cybernetics, the posthuman consequent and
the relationship to digital technology. Steve Nichols published the
Posthuman Movement manifesto in 1988. His early evolutionary theory of
mind (MVT) allows development of sentient E1 brains. The emphasis is on
systems. Transhumanism does not focus on either of these. Instead,
transhumanism focuses on the modification of the human species via any
kind of emerging science, including genetic engineering, digital
technology, and bioengineering. Transhumanism is sometimes criticized for not adequately addressing the scope of posthumanism and its concerns for the evolution of humanism.
As used in this article, "posthuman" does not necessarily refer to a conjectured future where humans are extinct or otherwise absent from the Earth. Kevin Warwick
says that both humans and posthumans will continue to exist but the
latter will predominate in society over the former because of their
abilities. Recently, scholars have begun to speculate that posthumanism provides
an alternative analysis of apocalyptic cinema and fiction, often casting vampires, werewolves, zombies and greys as potential evolutions of the human form and being. With these potential evolutions of humans and posthumans, human
centered designed ways of thinking needs to also be inclusive of these
new posthumans. The new "post human resists binary categories and,
instead, integrates the human and the nonhuman." Human centered thinking needs to be redone in a way to include posthumanism.
A variation on the posthuman theme is the notion of a
"posthuman god"; the idea that posthumans, being no longer confined to
the parameters of human nature, might grow physically and mentally so powerful as to appear possibly god-like by present-day human standards. This notion should not be interpreted as being related to the idea portrayed in some science fiction that a sufficiently advanced species may "ascend" to a higher plane of existence—rather,
it merely means that some posthuman beings may become so exceedingly
intelligent and technologically sophisticated that their behaviour would
not possibly be comprehensible to modern humans, purely by reason of
their limited intelligence and imagination.
Life extension is the concept of extending the human lifespan, either through incremental improvements in medicine or through radical increases in maximum lifespan beyond its generally-settled biological limit of around 125 years. This field of study has been explored by numerous researchers and advocates, including "life extensionists", "immortalists", and "longevists"
(those who aspire to achieve prolonged lifespans themselves). These
researchers and advocates hypothesize that future advancements in tissue
rejuvenation, stem cells, regenerative medicine, molecular repair, gene therapy, pharmaceuticals, and organ replacement (such as through artificial organs or xenotransplantations)
will eventually enable humans to have indefinite lifespans through
complete rejuvenation to a state of optimal health and youth (agerasia). The ethical implications of life extension are a subject of discourse among bioethicists.
The sale of purported anti-aging products, such as
supplements and hormone replacement therapy, is a lucrative global
industry. For example, the industry that promotes the use of hormones as
a treatment for consumers to slow or reverse the aging process in the US market generated about $50billion of revenue a year in 2009. The use of such hormone products has not been proven to be effective or safe. Similarly, a variety of apps make claims to assist in extending the life of their users, or predicting their lifespans.
During the process of aging, an organism accumulates damage to its macromolecules, cells, tissues, and organs.
Specifically, aging is characterized as and thought to be caused by
"genomic instability, telomere attrition, epigenetic alterations, loss
of proteostasis, deregulated nutrient sensing, mitochondrial dysfunction, cellular senescence, stem cell exhaustion, and altered intercellular communication." Oxidation damage to cellular contents caused by free radicals is believed to contribute to aging as well.
The longest documented human lifespan is 122 years 164 days, the case of Jeanne Calment, who according to records was born in 1875 and died in 1997, whereas the maximum lifespan of a wildtype mouse, commonly used as a model in research on aging, is about three years. Genetic differences between humans and mice that may account for these
different aging rates include differences in efficiency of DNA repair, antioxidant defenses, energy metabolism, proteostasis maintenance, and recycling mechanisms such as autophagy.
The average life expectancy in a population is lowered by infant and child mortality, which are frequently linked to infectious diseases or nutrition problems. Later in life, vulnerability to accidents and age-related chronic disease such as cancer or cardiovascular disease
play an increasing role in mortality. Extension of life expectancy and
lifespan can often be achieved by access to improved medical care, vaccinations, good diet, exercise, and avoidance of hazards such as smoking.
Maximum lifespan is determined by the rate of aging for a species inherent in its genes and by environmental factors. Widely recognized methods of extending maximum lifespan in model organisms such as nematodes, fruit flies, and mice include caloric restriction, gene manipulation, and administration of pharmaceuticals. Another technique uses evolutionary pressures such as breeding from
only older members or altering levels of extrinsic mortality. Some animals such as hydra, planarian flatworms, and certain sponges, corals, and jellyfish do not die of old age and exhibit potential immortality.
The extension of life has been a desire of humanity and a
mainstay motif in the history of scientific pursuits and ideas
throughout history, from the Sumerian Epic of Gilgamesh and the Egyptian Smith medical papyrus, all the way through the Taoists, Ayurveda practitioners, alchemists, hygienists such as Luigi Cornaro, Johann Cohausen and Christoph Wilhelm Hufeland, and philosophers such as Francis Bacon, René Descartes, Benjamin Franklin and Nicolas Condorcet.
However, the beginning of the modern period in this endeavor can be
traced to the end of the 19th – beginning of the 20th century, to the
so-called "fin-de-siècle"
(end of the century) period, denoted as an "end of an epoch" and
characterized by the rise of scientific optimism and therapeutic
activism, entailing the pursuit of life extension (or
life-extensionism). Among the foremost researchers of life extension at
this period were the Nobel Prize winning biologist Elie Metchnikoff (1845-1916) -- the author of the cell theory of immunity and vice director of Institut Pasteur in Paris, and Charles-Édouard Brown-Séquard (1817-1894) -- the president of the French Biological Society and one of the founders of modern endocrinology.
Sociologist James Hughes claims that science has been tied to a cultural narrative of conquering death since the Age of Enlightenment. He cites Francis Bacon (1561–1626) as an advocate of using science and reason to extend human life, noting Bacon's novel New Atlantis, wherein scientists worked toward delaying aging and prolonging life. Robert Boyle (1627–1691), founding member of the Royal Society,
also hoped that science would make substantial progress with life
extension, according to Hughes, and proposed such experiments as "to
replace the blood of the old with the blood of the young". Biologist Alexis Carrel (1873–1944) was inspired by a belief in indefinite human lifespan that he developed after experimenting with cells, says Hughes.
Contemporary
Regulatory and legal struggles between the Food and Drug Administration (FDA) and the Life Extension organization included seizure of merchandise and court action. In 1991, Saul Kent and Bill Faloon, the principals of the organization, were jailed for four hours and were released on $850,000 bond each. After 11 years of legal battles, Kent and Faloon convinced the US
Attorney's Office to dismiss all criminal indictments brought against
them by the FDA.
In 2003, Doubleday published "The Immortal Cell: One Scientist's Quest to Solve the Mystery of Human Aging," by Michael D. West. West emphasised the potential role of embryonic stem cells in life extension.
Other modern life extensionists include writer Gennady Stolyarov, who insists that death is "the enemy of us all, to be fought with medicine, science, and technology"; transhumanist philosopher Zoltan Istvan, who proposes that the "transhumanist must safeguard one's own existence above all else"; futurist George Dvorsky, who considers aging to be a problem that desperately needs to be solved; and recording artist Steve Aoki, who has been called "one of the most prolific campaigners for life extension".
In 2003, Aubrey de Grey and David Gobel formed the Methuselah Foundation, which gives financial grants to anti-aging research projects. In 2009, de Grey and several others founded the SENS Research Foundation,
a California-based scientific research organization which conducts
research into aging and funds other anti-aging research projects at
various universities. In 2013, Google announced Calico,
a new company based in San Francisco that will harness new technologies
to increase scientific understanding of the biology of aging. It is led by Arthur D. Levinson, and its research team includes scientists such as Hal V. Barron, David Botstein, and Cynthia Kenyon. In 2014, biologist Craig Venter
founded Human Longevity Inc., a company dedicated to scientific
research to end aging through genomics and cell therapy. They received
funding with the goal of compiling a comprehensive human genotype,
microbiome, and phenotype database.
Aside from private initiatives, aging research is being conducted in university laboratories, and includes universities such as Harvard and UCLA.
University researchers have made a number of breakthroughs in extending
the lives of mice and insects by reversing certain aspects of aging.
Research
Theoretically, extension of maximum lifespan in humans could be achieved by reducing the rate of aging damage by periodic replacement of damaged tissues, molecular repair or rejuvenation of deteriorated cells and tissues, reversal of harmful epigenetic changes, or the enhancement of enzyme telomerase activity.
Research geared towards life extension strategies in
various organisms is currently under way at a number of academic and
private institutions. Since 2009, investigators have found ways to
increase the lifespan of nematode worms and yeast by 10-fold; the record
in nematodes was achieved through genetic engineering and the extension in yeast by a combination of genetic engineering and caloric restriction. A 2009 review of longevity research noted: "Extrapolation from worms to
mammals is risky at best, and it cannot be assumed that interventions
will result in comparable life extension factors. Longevity gains from
dietary restriction, or from mutations studied previously, yield smaller
benefits to Drosophila than to nematodes, and smaller still to mammals.
This is not unexpected, since mammals have evolved to live many times
the worm's lifespan, and humans live nearly twice as long as the next
longest-lived primate. From an evolutionary perspective, mammals and
their ancestors have already undergone several hundred million years of
natural selection favoring traits that could directly or indirectly
favor increased longevity, and may thus have already settled on gene
sequences that promote lifespan. Moreover, the very notion of a
"life-extension factor" that could apply across taxa presumes a linear
response rarely seen in biology."
Anti-aging/life-extension drugs
There are numerous chemicals intended to slow the aging process under study in animal models. One type of research is related to the observed effects of a calorie restriction (CR) diet, which has been shown to extend lifespan in some animals. Based on that research, there have been attempts to develop drugs that
will have the same effect on the aging process as a CR diet, which are
known as caloric restriction mimetic drugs, such as rapamycin and metformin.
While agents such as these have some limited laboratory
evidence of efficacy in animals, there are no studies to date in humans
for drugs that may promote life extension, mainly because research
investment remains at a low level, and regulatory standards are high. Aging is not recognized as a preventable condition by governments,
indicating there is no clear pathway to approval of anti-aging
medications. Further, anti-aging drug candidates are under constant review by regulatory authorities like the US Food and Drug Administration, which stated in 2023 that "no medication has been proven to slow or reverse the aging process."
LDL-C lowering drugs such as statins and PCSK9 inhibitors
present with some of the most promising candidates for increasing
lifespan since there is substantial randomized genetic and clinical
evidence that reduced risk of atherosclerotic cardiovascular disease via
reducing LDL-C would yield a net gain in lifespan.
Nanotechnology
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 machines, including ones operating within cells and utilizing as yet hypothetical molecular computers, 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. 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 nanomachines (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.
The replacement of biological organs, which are
susceptible to diseases, with mechanical ones has the potential to
extend life. This is the goal of the 2045 Initiative.
Cryonics is the low-temperature freezing (usually at −196°C or −320.8°F or 77.1K) of a human corpse, with the hope that resuscitation may be possible in the future. It is regarded with skepticism within the mainstream scientific community and has been characterized as quackery.
While some biogerontologists find these ideas "worthy of discussion", others contend that the alleged benefits are too speculative given the
current state of technology, referring to it as "fantasy rather than
science".
Genome editing, in which nucleic acid polymers are delivered as a drug and are either expressed
as proteins, interfere with the expression of proteins, or correct
genetic mutations, has been proposed as a future strategy to prevent
aging.
CRISPR/Cas9 edits genes by precisely cutting DNA and then
harnessing natural DNA repair processes to modify the gene in the
desired manner. The system has two components: the Cas9 enzyme and a
guide RNA. A large array of genetic modifications have been found to increase
lifespan in model organisms such as yeast, nematode worms, fruit flies,
and mice. As of 2013, the longest extension of life caused by a single
gene manipulation was roughly 50% in mice and 10-fold in nematode worms.
"Healthspan, parental lifespan, and longevity are highly genetically correlated."
In July 2020 scientists, using public biological data on 1.75 m people with known lifespans overall, identify 10 genomic loci which appear to intrinsically influence healthspan, lifespan, and longevity – of which half have not been reported previously at genome-wide significance and most being associated with cardiovascular disease – and identify haem metabolism
as a promising candidate for further research within the field. Their
study suggests that high levels of iron in the blood likely reduce, and
genes involved in metabolising iron likely increase healthy years of
life in humans. The same month other scientists report that yeast cells of the same
genetic material and within the same environment age in two distinct
ways, describe a biomolecular mechanism that can determine which process
dominates during aging and genetically engineer a novel aging route with substantially extended lifespan.
Fooling genes
In The Selfish Gene, Richard Dawkins describes an approach to life-extension that involves "fooling genes" into thinking the body is young.[76] Dawkins attributes inspiration for this idea to Peter Medawar.
The basic idea is that our bodies are composed of genes that activate
throughout our lifetimes, some when we are young and others when we are
older. Presumably, these genes are activated by environmental factors,
and the changes caused by these genes activating can be lethal. It is a
statistical certainty that we possess more lethal genes that activate in
later life than in early life. Therefore, to extend life, we should be
able to prevent these genes from switching on, and we should be able to
do so by "identifying changes in the internal chemical environment of a
body that take place during aging... and by simulating the superficial
chemical properties of a young body".
Cloning and body part replacement
Some life extensionists suggest that therapeutic cloning and stem cell research could one day provide a way to generate cells, body parts, or even entire bodies (generally referred to as reproductive cloning)
that would be genetically identical to a prospective patient. In 2008,
the US Department of Defense announced a program to research the
possibility of growing human body parts on mice. Complex biological structures, such as mammalian joints and limbs, have
not yet been replicated. Dog and primate brain transplantation
experiments were conducted in the mid-20th century but failed due to rejection
and the inability to restore nerve connections. As of 2006, the
implantation of bio-engineered bladders grown from patients' own cells
has proven to be a viable treatment for bladder disease. Proponents of body part replacement and cloning contend that the
required biotechnologies are likely to appear earlier than other
life-extension technologies.
The use of human stem cells, particularly embryonic stem cells,
is controversial. Opponents' objections generally are based on
interpretations of religious teachings or ethical considerations. Proponents of stem cell research point out that cells are routinely
formed and destroyed in a variety of contexts. Use of stem cells taken
from the umbilical cord or parts of the adult body may not provoke
controversy.
The controversies over cloning are similar, except general public opinion in most countries stands in opposition to reproductive cloning.
Some proponents of therapeutic cloning predict the production of whole
bodies, lacking consciousness, for eventual brain transplantation.
Ethics and politics
Scientific controversy
Some critics dispute the portrayal of aging as a disease. For example, Leonard Hayflick, who determined that fibroblasts are limited to around 50cell divisions, reasons that aging is an unavoidable consequence of entropy. Hayflick and fellow biogerontologistsJay Olshansky
and Bruce Carnes have strongly criticized the anti-aging industry in
response to what they see as unscrupulous profiteering from the sale of
unproven anti-aging supplements.
Consumer motivations
Research by Sobh and Martin (2011) suggests that people
buy anti-aging products to obtain a hoped-for self (e.g., keeping a
youthful skin) or to avoid a feared-self (e.g., looking old). The
research shows that when consumers pursue a hoped-for self, it is
expectations of success that most strongly drive their motivation to use
the product. The research also shows why doing badly when trying to
avoid a feared self is more motivating than doing well. When product use
is seen to fail it is more motivating than success when consumers seek
to avoid a feared-self.
Political parties
Though many scientists state that life extension and radical life extension are possible, there are
still no international or national programs focused on radical life
extension. There are political forces working both for and against life
extension. By 2012, in Russia, the United States, Israel, and the
Netherlands, the Longevity political parties started. They aimed to
provide political support to radical life extension research and
technologies, and ensure the fastest possible and at the same time soft
transition of society to the next step – life without aging and with
radical life extension, and to provide access to such technologies to
most currently living people.
Leon Kass (chairman of the US President's Council on Bioethics from 2001 to 2005) has questioned whether potential exacerbation of overpopulation problems would make life extension unethical. He states his opposition to life extension with the words:
"simply
to covet a prolonged life span for ourselves is both a sign and a cause
of our failure to open ourselves to procreation and to any higher
purpose ... [The] desire to prolong youthfulness is not only a childish
desire to eat one's life and keep it; it is also an expression of a
childish and narcissistic wish incompatible with devotion to posterity."
John Harris, former editor-in-chief of the Journal of
Medical Ethics, argues that as long as life is worth living, according
to the person himself, we have a powerful moral imperative to save the
life and thus to develop and offer life extension therapies to those who
want them.
TranshumanistphilosopherNick Bostrom
has argued that any technological advances in life extension must be
equitably distributed and not restricted to a privileged few. In an extended metaphor entitled "The Fable of the Dragon-Tyrant",
Bostrom envisions death as a monstrous dragon who demands human
sacrifices. In the fable, after a lengthy debate between those who
believe the dragon is a fact of life and those who believe the dragon
can and should be destroyed, the dragon is finally killed. Bostrom
argues that political inaction allowed many preventable human deaths to
occur.
Overpopulation concerns
Controversy about life extension is due to fear of overpopulation and possible effects on society. Biogerontologist Aubrey De Grey counters the overpopulation critique by pointing out that the therapy could postpone or eliminate menopause, allowing women to space out their pregnancies over more years and thus decreasing the yearly population growth rate. Moreover, the philosopher and futurist Max More
argues that, given that the worldwide population growth rate is slowing
down and is projected to eventually stabilize and begin falling,
superlongevity would be unlikely to contribute to overpopulation.
Opinion polls
A Spring 2013 Pew Research
poll in the United States found that 38% of Americans would want life
extension treatments, and 56% would reject it. However, it also found
that 68% believed most people would want it and that only 4% consider an
"ideal lifespan" to be more than 120 years. The median "ideal lifespan"
was 91 years of age and the majority of the public (63%) viewed medical
advances aimed at prolonging life as generally good. 41% of Americans
believed that radical life extension (RLE) would be good for society,
while 51% said they believed it would be bad for society. One possibility for why 56% of Americans claim they would reject life
extension treatments may be due to the cultural perception that living
longer would result in a longer period of decrepitude, and that the
elderly in our current society are unhealthy.
Religious people are no more likely to oppose life extension than the unaffiliated, though some variation exists between religious denominations.
Aging as a disease
Most mainstream medical organizations and practitioners do not consider aging to be a disease. Biologist David Sinclair says: "Idon't see aging as a disease, but as a collection of quite predictable diseases caused by the deterioration of the body." The two main arguments used are that aging is both inevitable and universal while diseases are not. However, not everyone agrees. Harry R. Moody, director of academic affairs for AARP, notes that what is normal and what is disease strongly depend on a historical context. David Gems, assistant director of the Institute of Healthy Ageing, argues that aging should be viewed as a disease. In response to the universality of aging, David Gems notes that it is as misleading as arguing that Basenji are not dogs because they do not bark. Because of the universality of aging he calls it a "special sort of
disease". Robert M. Perlman, coined the terms "aging syndrome" and
"disease complex" in 1954 to describe aging.
The discussion whether aging should be viewed as a disease
or not has important implications. One view is, this would stimulate
pharmaceutical companies to develop life extension therapies and in the
United States of America, it would also increase the regulation of the
anti-aging market by the Food and Drug Administration (FDA). Anti-aging now falls under the regulations for cosmetic medicine which are less tight than those for drugs.
A senolytic (from the words senescence and -lytic, "decomposition or breakdown") is among a class of small molecules under basic research to determine if they can selectively induce death of senescent cells and improve health in humans. A goal of this research is to discover or develop agents to delay, prevent, alleviate, or reverse age-related diseases. Removal of senescent cells with senolytics has been proposed as a method of enhancing immunity during aging.
A related concept is "senostatic", which means to suppress senescence.
Senolytics eliminate senescent cells whereas senomorphics – with candidates such as Apigenin, Everolimus and Rapamycin – modulate properties of senescent cells without eliminating them, suppressing phenotypes of senescence, including the SASP. Senomorphic effects may be one major effect mechanism of a range of
prolongevity drug candidates. Such candidates are however typically not
studied for just one mechanism, but multiple. There are biological databases
of prolongevity drug candidates under research as well as of potential
gene/protein targets. These are enhanced by longitudinal cohort studies, electronic health records, computational (drug) screening methods, computational biomarker-discovery methods and computational biodata-interpretation/personalized medicine methods.
Many prolongevity drugs are synthetic alternatives or potential complements to existing nutraceuticals, such as various sirtuin-activating compounds under investigation like SRT2104. In some cases pharmaceutical administration is combined with that of neutraceuticals – such as in the case of glycine combined with NAC. Often studies are structured based on or thematize specific
prolongevity targets, listing both nutraceuticals and pharmaceuticals
(together or separately) such as FOXO3-activators.
Researchers are also exploring ways to mitigate side-effects from such substances (possibly most notably rapamycin and its derivatives) such as via protocols of intermittent administration and have called for research that helps determine optimal treatment schedules (including timing) in general.
The free-radical theory of aging suggests that antioxidant
supplements might extend human life. Reviews, however, have found that
use of vitamin A (as β-carotene) and vitamin E supplements possibly can
increase mortality.Other reviews have found no relationship between vitamin E and other vitamins with mortality. Vitamin D supplementation of various dosages is investigated in trials and there also is research into GlyNAC (see above).
Complications
Complications of antioxidant supplementation (especially continuous high dosages far above the RDA) include that reactive oxygen species
(ROS), which are mitigated by antioxidants, "have been found to be
physiologically vital for signal transduction, gene regulation, and
redox regulation, among others, implying that their complete elimination
would be harmful". In particular, one way of multiple they can be
detrimental is by inhibiting adaptation to exercise such as muscle hypertrophy (e.g. during dedicated periods of caloric surplus). There is also research into stimulating/activating/fueling endogenous
antioxidant generation, in particular e.g. of neutraceutical glycine and
pharmaceutical NAC. Antioxidants can change the oxidation status of different e.g. tissues,
targets or sites each with potentially different implications,
especially for different concentrations. A review suggests mitochondria have a hormetic response to ROS, whereby low oxidative damage can be beneficial.
As of 2021, there is no clinical evidence that any dietary restriction practice contributes to human longevity.
Healthy diet
Research suggests that increasing adherence to Mediterranean diet patterns is associated with a reduction in total and cause-specific mortality, extending health- and lifespan. Research is identifying the key beneficial components of the Mediterranean diet. Studies suggest dietary changes are a factor of national relative rises in life-span.
keeping alcohol consumption of any type at a minimum – conventional Mediterranean diets include alcohol consumption (i.e. of wine), which is under research due to data suggesting negative long-term brain impacts even at low/moderate consumption levels.
fully replacing refined grains – some guidelines of Mediterranean diets do not clarify or include the principle of whole-grain consumption instead of refined grains. Whole grains are included in Mediterranean diets.
Other approaches
Further advanced biosciences-based approaches include:
Endogenous circulating biomolecules: Blood proteins
of blood from young animals have shown some pro-longevity potential in
animal studies (e.g. via transfer of blood or plasma, and of plasma
proteins). Moreover, exerkines – signalling biomolecules released during/after exercise – have also shown promising results. Exerkines include myokines. Extracellular vesicles were shown to be secreted concomitantly with exerkines and are also investigated. (See also: body fluid and cerebrospinal fluid)
Personalized interventions: future studies may tailor and investigate personalized medicine-type interventions. For instance, effects of interventions or e.g. dosages may vary per age and/or genome. A review suggests that the field of precision medicine and geroscience will have to interact closely (see also: combination therapy)
Mitochondria modulation: early-stage
research indicates mitochondrial interventions such as mitochondrial
transplantation may have potential to be efficacious
There is a need and research into the development of aging biomarkers such as the epigenetic clock "to assess the ageing process and the efficacy of interventions to bypass the need for large-scale longitudinal studies".Such biomarkers may also include in vivo brain imaging.
Reviews sometimes include structured tables that provide
systematic overviews of intervention/drug candidates with a review
calling for integrating "current knowledge with multi-omics, health
records, and drug safety data to predict drugs that can improve health
in late life" and listing major outstanding questions. Biological databases
of prolongevity drug candidates under research as well as of potential
gene/protein targets include GenAge, DrugAge and Geroprotectors.
A review has pointed out that the approach of
"'epidemiological' comparison of how a low versus a high consumption of
an isolated macronutrient and its association with health and mortality
may not only fail to identify protective or detrimental nutrition
patterns but may lead to misleading interpretations". It proposes a
multi-pillar approach, and summarizes findings towards constructing –
multi-system-considering and at least age-personalized dynamic – refined
longevity diets. Epidemiological-type observational studies included in
meta-analyses should according to the study at least be complemented by
"(1) basic research focused on lifespan and healthspan, (2) carefully
controlled clinical trials, and (3) studies of individuals and
populations with record longevity".
Hormone treatment
The anti-aging industry offers several hormone therapies. Some of these have been criticized for possible dangers and a lack of proven effect. For example, the American Medical Association has been critical of some anti-aging hormone therapies.
While growth hormone
(GH) decreases with age, the evidence for use of growth hormone as an
anti-aging therapy is mixed and based mostly on animal studies. There
are mixed reports that GH or IGF-1 modulates the aging process in humans and about whether the direction of its effect is positive or negative.
Klotho and exerkines (see above) like irisin are being investigated for potential pro-longevity therapies.
Loneliness/isolation, social life and support, exercise/physical activity (partly via neurobiological effects and increased NAD+ levels), psychological characteristics/personality (possibly highly indirectly), sleep duration, circadian rhythms (patterns of sleep, drug-administration and feeding), type of leisure activities, not smoking, altruistic emotions and behaviors, subjective well-being, mood and stress (including via heat shock protein) are investigated as potential (modulatable) factors of life extension.
Healthy lifestyle practices and healthy diet have been
suggested as "first-line function-preserving strategies, with
pharmacological agents, including existing and new pharmaceuticals and
novel 'nutraceutical' compounds, serving as potential complementary
approaches".
Collectively, addressing common causes of death could extend lifespans of populations and humanity overall. For instance, a 2020 study indicates that the global mean loss of life expectancy (LLE) from air pollution
in 2015 was 2.9 years, substantially more than, for example, 0.3 years
from all forms of direct violence, albeit a significant fraction of the
LLE (a measure similar to years of potential life lost) is considered to be unavoidable.
Regular screening and doctor visits has been suggested as a lifestyle-societal intervention. (See also: medical test and biomarker)
Health policy
and changes to standard healthcare could support the adoption of the
field's conclusions – a review suggests that the longevity diet would be
a "valuable complement to standard healthcare and that, taken as a
preventative measure, it could aid in avoiding morbidity, sustaining
health into advanced age" as a form of preventive healthcare.
It has been suggested that in terms of healthy diets,
Mediterranean-style diets could be promoted by countries for ensuring
healthy-by-default choices ("to ensure the healthiest choice is the
easiest choice") and with highly effective measures including dietary education, food checklists and recipes that are "simple, palatable, and affordable".
A review suggests that "targeting the aging process per se
may be a far more effective approach to prevent or delay
aging-associated pathologies than treatments specifically targeted to
particular clinical conditions".
Low ambient temperature
Low ambient temperature as a physical factor affecting
free radical levels was identified as a treatment producing exceptional
lifespan increase in Drosophila melanogaster and other living beings.
As of 2017, some clinics offered injection of blood plasma from young donors. The alleged benefits of the treatment, none of which had been proven, included a longer life. The approach was based on parabiosis studies in mice.
In 2019, after receiving an FDA warning letter to cease giving people plasma infusions, one American company that promoted the treatment, Ambrosia, withdrew from clinical trials it had conducted without FDA approval. The FDA had stated "that some patients are being preyed upon by
unscrupulous actors touting treatments of plasma from young donors as
cures and remedies."
The treatment appeared in HBO's Silicon Valley fiction series.
One hypothetical future strategy that, as some suggest, "eliminates" the complications related to a physical body, involves the
copying or transferring (e.g. by progressively replacing neurons with
transistors) of a conscious mind from a biological brain to a
non-biological computer system or computational device. The basic idea
is to scan the structure of a particular brain in detail, and then
construct a software model of it that is so faithful to the original
that, when run on appropriate hardware, it will behave in essentially
the same way as the original brain. Whether or not an exact copy of one's mind constitutes actual life extension is matter of debate.
However, critics argue that the uploaded mind would simply be a clone and not a true continuation of a person's consciousness.
Some scientists believe that the dead may one day be "resurrected" through simulation technology.
