Longevity

Longevity is about life expectancy, and as a civilization advances with medical technology and quality of life, longevity improves. The range for the evolution of homo sapiens is around 30 (Type 0.1) for a fully grown adult to over 5000 years (Type IV), making one effectively immortal.

A reduction in current lifestyle diseases, such as obesity, diabetes, hypertension, and heart disease, will improve longevity. Michio Kaku argues that genetic engineering, nanotechnology and future breakthroughs will accelerate the rate of life expectancy indefinitely. Already genetic engineering has allowed the life expectancy of certain primates to be doubled, and for human skin cells in labs to divide and live indefinitely without becoming cancerous.

Senescence is the condition or process of deterioration with age, or the loss of a cell's power of division and growth.

Gerontology
Gerontology is the science of physiological aging and death.

There are three main causes of death:

Aging
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. SENS (discussed later) could eliminate aging.

Disease
Disease can be eradicated via medical technology. Methods of detecting diseases early are important as is preventative medicine. Neurodegenerative diseases are curable with the use of stem cells; telomere manipulation for cancer; vaccines for AIDS, tuberculosis and COVID; gene therapy for diabetes and cancer; and drugs for a myriad of diseases and ailments.

Trauma
Physical trauma is the final threat, as a biologically immortal person would still be subject to unforeseen accidents or catastrophes. A body that could automatically repair itself from severe trauma (with nanotechnology) would mitigate this factor.

There is no single medical reason for aging. The twice Nobel laureate Dr. Linus Pauling asserted: "Death is unnatural. Theoretically, man is quite immortal. His body tissues replace themselves. He is a self-repairing machine. And yet, he gets old and dies, and the reasons for this are still a mystery".

There are three primary "clocks of aging":

Wear and tear
The body deteriorates from accident or hard usage after a number of years, depending on lifestyle or bad luck.

Cell division
Young human cells can divide only a limited number of times (roughly 50 generations) before all their descendants age and die. Adult cells divide even fewer times (about 20) before death ensues. Animals with longer lifespans have the longest-lived cells. 50 divisions would mean a life expectancy of 70 to 80 years, whereas a tortoise has 90-125 divisions with a life expectancy of 150 to 200 years. Aging thus appears to be a built-in genetic limitation to cellular regeneration and growth.

Hormonal
The third clock of aging is hormonal in nature, found in human endocrine glands. Most people die because of a failure of one of the two major body systems: the cardiovascular or the immune systems. Death occurs from heart stoppage or from an inability of the blood vessels to deliver oxygen and nutrients to vital organs, or from a failure of the body’s immune system to ward off an attack of invading microorganisms. The thyroid gland produces thyroxine which is the master rate-controlling hormone. The pituitary may release some kind of blocking hormone (a death hormone) that prevents cells from using thyroxine, leading to increased destructive oxidation, chromosomal mutations and heart tissue dysfunction.

Another endocrine gland, the thymus, has been implicated in aging. The level of thymosin (the secretion of the thymus gland decreases with age, and the failure rate of the human immune system rises markedly. Lymphocytes, our "white cells," become increasingly incompetent. They fail to rid the body of hostile pathogens and mistakenly attack the body’s own cells as if they were foreign invaders. As a result, older organisms are vastly more susceptible to a wide range of potentially lethal diseases.

Defusing the aging time bomb
Three clocks of aging are simultaneously ticking against us. Defusing each stage increases our life expectancy dramatically:

Stage 1: Hormonal imbalances occur which cause the cardiovascular and immune systems ultimately to fail. This is the body’s primary self-destruct mechanism. Typical life expectancy: 30-80 years.

Stage 2: The cellular aging program causes body cells to cease dividing after a fixed number of generations. This is the body’s secondary self-destruct mechanism. Typical life expectancy: 110-120 years.

Stage 3: Wear and tear on body structures. Irreversible genetic deterioration or severe accidental trauma eventually cause senescence and death. This is the body’s last line of defense against immortality. Typical life expectancy: 1000 years.

Regenerative medicine
This is bioengineering to replace or regenerate cells, tissues or organs. Tissues and organs may be grown in the laboratory when the body cannot be stimulated to heal itself. Methods include the injection of stem cells or progenitor cells via cell therapies; infused cell immunomodulation therapy; and transplantation of in vitro grown organs and tissues via tissue engineering.

Strategies for engineered negligible senescence (SENS) proposes that rejuvenation may be obtained by removing aging damage via the use of stem cells and tissue engineering, telomere-lengthening machinery, immunotherapeutic clearance, and other novel ideas.

Anti-aging drugs
The enzyme telomerase could be used to counter the process of telomere shortening. Telomeres form the ends of human chromosomes. Telomeres shorten with each round of cell division and this mechanism limits proliferation of human cells to a finite number of cell divisions by inducing replicative senescence.

Cancer cells are immortal. Cellular senescence does not occur in most cancer cells due to telomerase. A treatment for cancer is the usage of telomerase inhibitors that would prevent the restoration of the telomere, allowing the cell to die like other body cells.

Autophagy
Autophagy, meaning "self-devouring", is the natural mechanism of a cell that removes unnecessary or dysfunctional components, thereby allowing recycling of cellular parts and homeostasis of cells. Autophagy is seen as an adaptive response to stress, promoting survival of the cell, but in other cases it promotes cell death and morbidity. Insufficient autophagy is one of the main reasons for the accumulation of damaged cells and aging.

Autophagy plays an important role in cancer – both in protecting against cancer as well as potentially contributing to the growth of cancer. It acts as both a tumor suppressor and a factor in tumor cell survival. Recent research has shown, however, that autophagy is more likely to be used as a tumor suppressor according to several models. Autophagy is also linked to inflammation, Parkinson’s disease and diabetes, so using drugs to ensure the correct functioning of autophagy will play a large role in disease reduction and anti-aging.

Nanotechnology
Tiny medical nanorobots could be created to go through human bloodstreams, find dangerous things like cancer cells and bacteria, and destroy them. Gene-therapies and nanotechnology will make the human body self-sustainable and capable of living indefinitely, able to continually create biological or synthetic replacement parts to replace damaged or dying ones. Nanomedicine could give rise to life extension through the repair of many processes thought to be responsible for aging. Moleculartronic computers could operate within cells and repairs could be automated or directed remotely. Raymond Kurzweil stated in his book The Singularity Is Near that advanced medical nanorobotics could completely remedy the effects of aging by 2030.

Cloning and body part replacement
Therapeutic cloning and stem cell research could provide a way to generate cells, body parts, or even entire bodies (reproductive cloning) that would be genetically identical to a patient.

The use of human 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.

The controversies over cloning are similar, similar to those found in teleportation. Successful cloning resulting in a sapient being would conclude that a human being is no more than the sum of his or her quantum parts, and directly confront a wealth of spiritual beliefs.

Another method of body part replacement involves progressively replacing neurons with transistors, altering a conscious mind from a biological brain to a non-biological computer system or computational device. The structure of a brain is scanned and a software model of it is made, so when run on appropriate hardware it will behave in the same way as the original brain. Where or not this is a true continuation of a person's consciousness is open to debate.

Cryonics
Cryonics is the low-temperature freezing of a human corpse, with the hope that resuscitation may be possible in the future. Some may even willingly freeze themselves while alive with the dream they may awake to a utopian future.

DNA damage
Naturally deficient DNA repair, allowing greater accumulation of DNA damages, causes premature aging, and increased DNA repair facilitates greater longevity. Nuclear DNA damage can contribute to aging either indirectly (by increasing apoptosis or cellular senescence) or directly (by increasing cell dysfunction). DNA damage occurs frequently and DNA repair processes have evolved to compensate.

A technology called CRISPR allows molecular biologists to alter the genes of any species with precision, by inducing DNA damage at a specific point and then altering DNA repair mechanisms to insert new genes or edit parts of a genome by removing, adding, or altering parts in a DNA sequence.

If DNA repair can be made to be 100% efficient using technology, this can lead to a dramatic increase in longevity.

Genetic editing
Genome editing to correct genetic mutations is a strategy to prevent aging. A 2020 study identified 10 genomes which influence health-span, lifespan, and longevity. Genes involved in metabolizing iron likely increase healthy years of life in humans. Yeast cells age in two distinct ways, and a biomolecular mechanism can fix which process dominates during aging and genetically engineer a novel aging route with substantially extended lifespan.

In The Selfish Gene, Richard Dawkins describes a life extension that involves "fooling genes" into thinking the body is young. 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".

Immortality
Immortality is eternal life or being exempt from death.

Biological immortality is an absence of aging. Cells that are not limited by the Hayflick limit are immortal, where they no longer divide because of DNA damage or shortened telomeres. 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.

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.

True immortality where it would be impossible to die is virtually indistinguishable from the afterlife, and such a being (like Q) would be god-like and eventually travel the planes of existence in the afterlife or beyond. It is a philosophical question if a being would want to live forever, as boredom and irritability might make them wish for death. Also, the human condition ensures that death comes to make way for "fresh" genes and adaptive thinking, ensuring the progression of mankind, rather than being mired in the old ways of thinking.

Mind and consciousness uploading can achieve a form of virtual or digital immortality.

A modern trend is amortality which is ageless living; an amortal appears age resistant, often in denial of mortality, using any means necessary to prolong life.

Mind uploading
The entire history of your online presence could be converted into an online entity by an AI after your death, and friends and family could interact with this entity is if it were alive. The entity might look like an avatar behaving, reacting, and thinking like a person on the basis of that person's digital archive. This avatar could remain static or continue to learn and self-improve autonomously, possibly becoming a seed AI.

With advances in VR, it would be possible to upload your mind and consciousness into a virchworld, thereby attaining a dubious form of immortality. This could be done when one is close to biological death, or even willingly in order to escape the woes of real life. There would be laws, ethics and living wills associated with this practice.

A mechanism for mind upload is to perform a detailed (MRI) scan of an organic brain and simulate the entire structure in a computer. An uploaded mind would only be a copy of the original mind, and not the conscious mind of the living entity associated in such a transfer. With a simultaneous upload of consciousness, the original living entity achieves immortality. Neural correlates of consciousness (NCC) is early research into the neural correlations of consciousness phenomena.

Senotherapy
This uses therapeutic agents and strategies to target cellular senescence, an altered cell state associated with ageing and age-related diseases.


 * Geroprotectors are prevent or reverse the senescent state by preventing triggers of cellular senescence, such as DNA damage, oxidative stress, proteotoxic stress, telomere shortening, melatonin, carnosine, metformin, nicotinamide mononucleotide (NMN) and delta sleep-inducing peptide.


 * SASP inhibitors – agents interfering with pro-inflammatory Senescence Associated Secretory Phenotype (SASP) production


 * Senolytics are small molecules that induce death of senescent cells and improve health in humans. Senolytics are used to delay, prevent, alleviate, or reverse age-related diseases.


 * Senomorphics – small molecules that suppress senescent phenotypes without killing cells

Young blood injection
The injection of blood products from young donors give the benefits of a longer life, darker hair, better memory, better sleep, curing heart diseases, diabetes and Alzheimer's disease.

Posthumanism and Cyborgs
Posthumans are "beyond human" by using primarily cybernetics to become cyborgs, with a replacement of defective or diseased biological organs with mechanical ones to extend life. Posthumans could be completely synthetic artificial intelligences, or a mix of human and artificial intelligence, or uploaded consciousnesses, or cyborgs. To compare, transhumanism focuses on the modification of humans via any kind of emerging science, including genetic engineering, digital technology, and bioengineering.

Posthuman futures are postulated as alternative apocalyptic futures, with vampires, werewolves and zombies as potential evolutions of the human being.

Eventually a "posthuman god" may become so exceedingly intelligent and technologically sophisticated that they would be incomprehensible to modern humans.

Transhumanism
Transhumanism is a movement about the enhancement of the human condition using technologies able to enhance longevity, mood and cognitive abilities, and how to protect humanity against extinction.

One of the first professors of futurology, F. M. Esfandiary, first lectured about a transition to transhumanity in New York. Born in 1930, he changed his name to FM-2030 to reflect the hope and belief that he would live to celebrate his 100th birthday in 2030, saying that "the name 2030 reflects my conviction that the years around 2030 will be a magical time. In 2030 we will be ageless and everyone will have an excellent chance to live forever. 2030 is a dream and a goal". Unfortunately he died of cancer in 2000.

Transhumanists support the emergence and convergence of technologies including nanotechnology, biotechnology, information technology, cognitive science, simulated reality, artificial intelligence, superintelligence, 3D bioprinting, mind uploading, chemical brain preservation and cryonics. They believe that humans can and should use these technologies to become superhuman.

Some varieties within transhumanist thought are:


 * Extropianism - a proactive approach to human evolution.
 * Immortalism - radical life extension and technological immortality is possible and desirable
 * Postgenderism - elimination of gender in the human species through biotechnology and reproductive technologies.
 * Singularitarianism - the belief that a technological singularity is possible, with action to effect it and ensure its safety.
 * Technogaianism - technology can help restore Earth's environment should be a goal of environmentalists.
 * Equalism - equality for all citizens through even distribution of resources in the technological singularity era.