Ageing in humans refers to a multidimensional process of physical, psychological, and social change. Some dimensions of ageing grow and expand over time, while others decline. Reaction time, for example, may slow with age, while knowledge of world events and wisdom may expand.Ageing is an important part of all human societies reflecting the biological changes that occur, but also reflecting cultural and societal conventions. Roughly 100,000 people worldwide die each day of age-related causes.


Ageless is an adjective describing a person or thing whose age cannot be defined, is nonexistent, does not change, or having always existed without a beginning or a end (existing without having ever been born and will never die). It can also describe immortality, most specifically eternal youth.

Aging-associated diseases

An aging-associated disease is a disease that is seen with increasing frequency with increasing senescence. Essentially, aging-associated diseases are complications arising from senescence. Age-associated diseases are to be distinguished from the aging process itself because all adult animals age, save for a few rare exceptions, but not all adult animals experience all age-associated diseases. Aging-associated diseases do not refer to age-specific diseases, such as the childhood diseases chicken pox and measles. "Aging-associated disease" is used here to mean "diseases of the elderly". Nor should aging-associated diseases be confused with accelerated aging diseases, all of which are genetic disorders.


An antioxidant is a molecule that inhibits the oxidation of other molecules. Oxidation is a chemical reaction that transfers electrons or hydrogen from a substance to an oxidizing agent. Oxidation reactions can produce free radicals. In turn, these radicals can start chain reactions. When the chain reaction occurs in a cell, it can cause damage or death to the cell. Antioxidants terminate these chain reactions by removing free radical intermediates, and inhibit other oxidation reactions. They do this by being oxidized themselves, so antioxidants are often reducing agents such as thiols, ascorbic acid, or polyphenols.


In computing, an avatar is the graphical representation of the user or the user's alter ego or character. It may take either a three-dimensional form, as in games or virtual worlds, or a two-dimensional form as an icon in Internet forums and other online communities. It can also refer to a text construct found on early systems such as MUDs. It is an object representing the user. The term "avatar" can also refer to the personality connected with the screen name, or handle, of an Internet user.

Biodemography of human longevity

Biodemography is a multidisciplinary approach, integrating biological knowledge (studies on human biology and animal models) with demographic research on human longevity and survival. Biodemographic studies are important for understanding the driving forces of the current longevity revolution (dramatic increase in human life expectancy), forecasting the future of human longevity, and identification of new strategies for further increase in healthy and productive life span.

Biological immortality

Biological immortality refers to a stable or decreasing rate of mortality from cellular senescence as a function of chronological age. Various unicellular and multicellular species may achieve this state either throughout their existence or after living long enough. A biologically immortal living thing can still die from means other than senescence, such as through injury or disease.

Brain Death

Brain death is the irreversible end of all brain activity (including involuntary activity necessary to sustain life) due to total necrosis of the cerebral neurons following loss of brain oxygenation. It should not be confused with a persistent vegetative state. Patients classified as brain dead can have their organs surgically removed for organ donation. Brain death, either of the whole brain or the brain stem, is used as a legal indicator of death in many jurisdictions.

Caloric restriction mimetic

Caloric restriction mimetics (CRM) try to mimic the substantial anti-aging effects caloric restriction (CR) has on many laboratory animals. In other words, the administration of a CRM results in the same physiological changes seen in CR itself. One way CRM work is by influencing specific genes that ultimately affect either cell repair or cell death. A number of genes and pathways have also been shown to regulate the actions of CR in model organisms and these represent attractive targets for drug discovery and for developing CRM.


Known medically as a malignant neoplasm, is a broad group of various diseases, all involving unregulated cell growth. In cancer, cells divide and grow uncontrollably, forming malignant tumors, and invade nearby parts of the body. The cancer may also spread to more distant parts of the body through the lymphatic system or bloodstream. Not all tumors are cancerous. Benign tumors do not grow uncontrollably, do not invade neighboring tissues, and do not spread throughout the body.

Clinical Death

Clinical death is the medical term for cessation of blood circulation and breathing, the two necessary criteria to sustain life. It occurs when the heart stops beating in a regular rhythm, a condition called cardiac arrest.


Cryobiology is the branch of biology that studies the effects of low temperatures on living things. The word cryobiology is derived from the Greek words "cryo" = cold, "bios" = life, and "logos" = science. In practice, cryobiology is the study of biological material or systems at temperatures below normal. Materials or systems studied may include proteins, cells, tissues, organs, or whole organisms. Temperatures may range from moderately hypothermic conditions to cryogenic temperatures.


Cryopreservation is a process where cells or whole tissues are preserved by cooling to sub-zero temperatures, typically 77 K (= ?196 °C, the boiling point of liquid nitrogen). At these cold temperatures, any biological activity, including the biochemical reactions that would cause cell death, is effectively stopped. However, if cryoprotectant solutions are not used, the cells being preserved are likely to be damaged due to freezing during the cooling or thawing process.


A cyborg, short for "cybernetic organism", is a being with both organic and cybernetic parts. See for example biomaterials and bioelectronics. The term was coined in 1960 when Manfred Clynes and Nathan S. Kline used it in an article about the advantages of self-regulating human-machine systems in outer space.


Death is the permanent cessation of all biological functions that sustain a living organism. Phenomena which commonly bring about death include biological aging (senescence), predation, malnutrition, disease, suicide, murder and accidents or trauma resulting in terminal injury.

Degenerative disease

A degenerative disease is a disease in which the function or structure of the affected tissues or organs will progressively deteriorate over time, whether due to normal bodily wear or lifestyle choices such as exercise or eating habits.

Deoxyribonucleic acid (DNA)

A molecule encoding the genetic instructions used in the development and functioning of all known living organisms and many viruses. Along with RNA and proteins, DNA is one of the three major macromolecules that are essential for all known forms of life.

Digital immortality

Digital immortality (or "virtual immortality", or "immortality in silico") is storing a person's personality in a more durable media, i.e., a computer, and allowing it to communicate with people in the future. The result might look like an avatar behaving, reacting, and thinking like a person on the basis of that person's digital archive. After the death of the individual, this avatar could remain static or continue to learn and develop autonomously.

DNA damage theory of aging

The DNA damage theory of aging proposes that aging is a consequence of unrepaired accumulation of naturally occurring DNA damages. Damage in this context is a DNA alteration that has an abnormal structure. Although both mitochondrial and nuclear DNA damage can contribute to aging, nuclear DNA is the main subject of this analysis. Nuclear DNA damage can contribute to aging either indirectly (by increasing apoptosis or cellular senescence) or directly (by increasing cell dysfunction).

DNA repair

DNA repair is a collection of processes by which a cell identifies and corrects damage to the DNA molecules that encode its genome. In human cells, both normal metabolic activities and environmental factors such as UV light and radiation can cause DNA damage, resulting in as many as 1 million individual molecular lesions per cell per day.

DNA repair-deficiency disorder

A DNA repair-deficiency disorder is a medical condition due to reduced functionality of DNA repair. DNA repair defects can cause both an accelerated aging disease and an increased risk of cancer.


a female domestic sheep, and the first mammal to be cloned from an adult somatic cell, using the process of nuclear transfer. She was cloned by Ian Wilmut, Keith Campbell and colleagues at the Roslin Institute and the biotechnology company PPL Therapeutics near Edinburgh in Scotland. The funding for Dolly's cloning was provided by PPL Therapeutics and the Ministry of Agriculture.

Eternal Youth

Eternal youth is the concept of human physical immortality free of aging. The youth referred to is usually meant to be in contrast to the depredations of aging, rather than a specific age of the human lifespan.

Free Radicals

Free radicals play an important role in combustion, atmospheric chemistry, polymerization, plasma chemistry, biochemistry, and many other chemical processes. In living organisms, superoxide and nitric oxide and their reaction products regulate many processes, such as control of vascular tone and thus blood pressure. They also play a key role in the intermediary metabolism of various biological compounds.

Free-radical theory of aging

The free radical theory of aging (FRTA) states that organisms age because cells accumulate free radical damage over time. A free radical is any atom or molecule that has a single unpaired electron in an outer shell. While a few free radicals such as melanin are not chemically reactive, most biologically-relevant free radicals are highly reactive.For most biological structures, free radical damage is closely associated with oxidative damage. Antioxidants are reducing agents, and limit oxidative damage to biological structures by passivating them from free radicals.


A gene is a molecular unit of heredity of a living organism. It is a name given to some stretches of DNA and RNA that code for a polypeptide or for an RNA chain that has a function in the organism. Living beings depend on genes, as they specify all proteins and functional RNA chains. Genes hold the information to build and maintain an organism's cells and pass genetic traits to offspring. All organisms have many genes corresponding to various biological traits, some of which are immediately visible, such as eye color or number of limbs, and some of which are not, such as blood type, increased risk for specific diseases, or the thousands of basic biochemical processes that comprise life.

Gene therapy

Gene therapy is the use of DNA as a pharmaceutical agent to treat disease. It derives its name from the idea that DNA can be used to supplement or alter genes within an individual's cells as a therapy to treat disease. The most common form of gene therapy involves using DNA that encodes a functional, therapeutic gene to replace a mutated gene. Other forms involve directly correcting a mutation, or using DNA that encodes a therapeutic protein drug (rather than a natural human gene) to provide treatment. In gene therapy, DNA that encodes a therapeutic protein is packaged within a "vector", which is used to get the DNA inside cells within the body. Once inside, the DNA becomes expressed by the cell machinery, resulting in the production of therapeutic protein, which in turn treats the patient's disease.

Genetically modified organism

A genetically modified organism (GMO) is an organism whose genetic material has been altered using genetic engineering techniques. Organisms that have been genetically modified include micro-organisms such as bacteria and yeast, insects, plants, fish, and mammals. GMOs are the source of genetically modified foods, and are also widely used in scientific research and to produce goods other than food.


In modern molecular biology and genetics, the genome is the entirety of an organism's hereditary information. It is encoded either in DNA or, for many types of virus, in RNA. The genome includes both the genes and the non-coding sequences of the DNA/RNA.


Genomics is a discipline in genetics that applies recombinant DNA, DNA sequencing methods, and bioinformatics to sequence, assemble, and analyze the function and structure of genomes (the complete set of DNA within a single cell of an organism).

Gentic Code

The genetic code is the set of rules by which information encoded within genetic material (DNA or mRNA sequences) is translated into proteins (amino acid sequences) by living cells. Biological decoding is accomplished by the ribosome, which links amino acids in an order specified by mRNA, using transfer RNA (tRNA) molecules to carry amino acids and to read the mRNA three nucleotides at a time. The genetic code is highly similar among all organisms, and can be expressed in a simple table with 64 entries.


a sub-specialty of internal medicine and family medicine that focuses on health care of elderly people. It aims to promote health by preventing and treating diseases and disabilities in older adults. There is no set age at which patients may be under the care of a geriatrician or geriatric physician, a physician who specializes in the care of elderly people. Rather, this decision is determined by the individual patient's needs, and the availability of a specialist.


Gerontology (from the Greek ?????, geron, "old man" and -?????, -logy, "study of"; coined by Ilya Ilyich Mechnikov in 1903) is the study of the social, psychological and biological aspects of aging. It is distinguished from geriatrics, which is the branch of medicine that studies the diseases of older adults. Gerontologists include researchers and practitioners in the fields of biology, medicine, nursing, dentistry, social work, physical and occupational therapy, psychology, psychiatry, sociology, economics, political science, architecture, pharmacy, public health, housing and anthropology.

Hayflick limit

the number of times a normal human cell population will divide until cell division stops. Empirical evidence shows that the telomeres associated with each cell's DNA will get slightly shorter with each new cell division until they shorten to a critical length.

Hormone replacement therapy

a system of medical treatment for surgically menopausal, perimenopausal and postmenopausal women and transgender men. It is based on the idea that the treatment may prevent discomfort caused by diminished circulating estrogen and progesterone hormones, and in the case of the surgically or prematurely menopausal, that it may prolong life and may reduce incidence of dementia.


Immortality is the ability to live forever, or put another way, it is an immunity from death. It is unknown whether human physical (material) immortality is an achievable condition —biological forms have inherent limitations which may or may not be able to be overcome through medical interventions or engineering. And even should human biological immortality be achieved, people could still continue to die from unforeseeable traumatic events. In religious (typically Christian) contexts, immortality is often stated to be among the promises by God (or other deities) to human beings who show goodness or else follow divine law. Moreover, only God is regarded as truly immortal,hence it is only through God's resources for resurrection and salvation that human beings may transcend death and live eternally.

Indefinite lifespan

Indefinite lifespan or, indefinite life extension, is a term used in the life extension movement to refer to the longevity of humans, and other life-forms, under conditions in which aging can be effectively and completely prevented and treated. Such individuals would still be susceptible to accidental or intentional death by trauma, starvation, or infectious diseases, but not death from aging. Their lifespans would be "indefinite," because protection from the effects of aging on health does not guarantee survival. Some life extensionists consider the term "indefinite lifespan" technically more correct than "immortality" which, especially in religious contexts, implies an inability to die.

Intelligence amplification

refers to the effective use of information technology in augmenting human intelligence. The idea was first proposed in the 1950s and 1960s by cybernetics and early computer pioneers. IA is sometimes contrasted with AI (Artificial Intelligence), that is, the project of building a human-like intelligence in the form of an autonomous technological system such as a computer or robot. AI has encountered many fundamental obstacles, practical as well as theoretical, which for IA seem moot, as it needs technology merely as an extra support for an autonomous intelligence that has already proven to function. Moreover, IA has a long history of success, since all forms of information technology, from the abacus to writing to the Internet, have been developed basically to extend the information processing capabilities of the human mind.

Life expectancy

Life expectancy is the expected (in the statistical sense) number of years of life remaining at a given age. It is denoted by ex, which means the average number of subsequent years of life for someone now aged x, according to a particular mortality experience. (In technical literature, this symbol means the average number of complete years of life remaining, excluding fractions of a year. The corresponding statistic including fractions of a year, the normal meaning of life expectancy, has a symbol with a small circle over the e.) Because life expectancy is an average, a particular person may well die many years before or many years after their "expected" survival. The term "maximum life span" has a quite different meaning. The "median life span" is also a different concept although fairly similar to life expectancy numerically in most developed countries.

Life extension

the study of slowing down or reversing the processes of aging to extend both the maximum and average lifespan. Some researchers in this area, and "life extensionists" or "longevists" (those who wish to achieve longer lives themselves), believe that future breakthroughs in tissue rejuvenation with stem cells, molecular repair, and organ replacement (such as with artificial organs or xenotransplantations) will eventually enable humans to have indefinite lifespans (agerasia) through complete rejuvenation to a healthy youthful condition.


The word "longevity" is sometimes used as a synonym for "life expectancy" in demography - especially when it concerns someone or something lasting longer than expected (an ancient tree, for example) - however, the two words have slightly different definitions. In a similar dichotomy to "precision" and "accuracy", "longevity" refers to the average number of years that a single person lives, whereas "life expectancy" refers to the number of years that the average population lives. This is illustrated by the fact that a drastic increase in life expectancy (due to a larger portion of the population beginning to live longer) may be accompanied by a small increase in the overall longevity of the population.

Maximum Life Span

Maximum life span refers to a measure of the maximum amount of time one or more members of a population has been observed to survive between birth and death. The term can also denote an estimate of the maximum amount of time that a member of a given species could survive between life and death, provided circumstances that are optimal to their longevity.

Molecular cloning

Molecular cloning is a set of experimental methods in molecular biology that are used to assemble recombinant DNA molecules and to direct their replication within host organisms. The use of the word cloning refers to the fact that the method involves the replication of a single DNA molecule starting from a single living cell to generate a large population of cells containing identical DNA molecules. Molecular cloning generally uses DNA sequences from two different organisms: the species that is the source of the DNA to be cloned, and the species that will serve as the living host for replication of the recombinant DNA. Molecular cloning methods are central to many contemporary areas of modern biology and medicine.


Nanorobotics is the emerging technology field creating machines or robots whose components are at or close to the scale of a nanometer (10−9 meters). More specifically, nanorobotics refers to the nanotechnology engineering discipline of designing and building nanorobots, with devices ranging in size from 0.1–10 micrometers and constructed of nanoscale or molecular components.

Negligible senescence

Negligible senescence refers to the lack of symptoms of aging in a few select animals. More specifically, negligibly senescent animals do not have measurable reductions in their reproductive capability with age, or measurable functional decline with age. Death rates in negligibly senescent animals do not increase with age as they do in senescent organisms.


Neuropreservation is cryopreservation of the human brain with the intention of future resuscitation and regrowth of a healthy body around the brain. Usually the brain is left within the head for physical protection, so the whole head is cryopreserved. Neuropreservation is a type of cryonics procedure.


referred to as smart drugs, memory enhancers, neuro enhancers, cognitive enhancers, and intelligence enhancers, are drugs, supplements, nutraceuticals, and functional foods that purportedly improve mental functions such as cognition, memory, intelligence, motivation, attention, and concentration.


An extremely rare genetic disease wherein symptoms resembling aspects of aging are manifested at an early age. It is a genetic condition that occurs as a new mutation, and is rarely inherited. Although the term progeria applies strictly speaking to all diseases characterized by premature aging symptoms, and is often used as such, it is often applied specifically in reference to Hutchinson-Gilford Progeria Syndrome (HGPS).

Regenerative medicine

The "process of replacing or regenerating human cells, tissues or organs to restore or establish normal function". This field holds the promise of regenerating damaged tissues and organs in the body by replacing damaged tissue and/or by stimulating the body's own repair mechanisms to heal previously irreparable tissues or organs. Regenerative medicine also empowers scientists to grow tissues and organs in the laboratory and safely implant them when the body cannot heal itself. Importantly, regenerative medicine has the potential to solve the problem of the shortage of organs available for donation compared to the number of patients that require life-saving organ transplantation.


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.