Senescence or biological aging is the gradual deterioration of functional characteristics in living organisms. Whole organism senescence involves an increase in death rates or a decrease in fecundity with increasing age, at least in the later part of an organism's life cycle. However, the resulting effects of senescence can be delayed. The 1934 discovery that calorie restriction can extend lifespans by 50% in rats, the existence of species having negligible senescence, and the existence of potentially immortal organisms such as members of the genus Hydra have motivated research into delaying senescence and thus age-related diseases. Rare human mutations can cause accelerated aging diseases.
Ilya Ilyich Mechnikov, also spelled Élie Metchnikoff, was a zoologist from the Russian Empire of Moldavian noble ancestry best known for his pioneering research in immunology and thanatology. He and Paul Ehrlich were jointly awarded the 1908 Nobel Prize in Physiology or Medicine "in recognition of their work on immunity".
Life extension is the concept of extending the human lifespan, either modestly through improvements in medicine or dramatically by increasing the maximum lifespan beyond its generally-settled biological limit of around 125 years. Several researchers in the area, along with "life extensionists", "immortalists", or "longevists", postulate that future breakthroughs in tissue rejuvenation, stem cells, regenerative medicine, molecular repair, gene therapy, pharmaceuticals, and organ replacement will eventually enable humans to have indefinite lifespans through complete rejuvenation to a healthy youthful condition (agerasia). The ethical ramifications, if life extension becomes a possibility, are debated by bioethicists.
Longevity may refer to especially long-lived members of a population, whereas life expectancy is defined statistically as the average number of years remaining at a given age. For example, a population's life expectancy at birth is the same as the average age at death for all people born in the same year.
Gerontology is the study of the social, cultural, psychological, cognitive, and biological aspects of aging. The word was coined by Ilya Ilyich Mechnikov in 1903, from the Greek γέρων (gérōn), meaning "old man", and -λογία (-logía), meaning "study of". The field is distinguished from geriatrics, which is the branch of medicine that specializes in the treatment of existing disease in older adults. Gerontologists include researchers and practitioners in the fields of biology, nursing, medicine, criminology, dentistry, social work, physical and occupational therapy, psychology, psychiatry, sociology, economics, political science, architecture, geography, pharmacy, public health, housing, and anthropology.
Population ageing is an increasing median age in a population because of declining fertility rates and rising life expectancy. Most countries have rising life expectancy and an ageing population, trends that emerged first in developed countries but are now seen in virtually all developing countries. In most developed countries, the phenomenon of population aging began to gradually emerge in the late 19th century. The aging of the world population occurred in the late 20th century, with the proportion of people aged 65 and above accounting for 6% of the total population. This reflects the overall decline in the world's fertility rate at that time. That is the case for every country in the world except the 18 countries designated as "demographic outliers" by the United Nations. The aged population is currently at its highest level in human history. The UN predicts the rate of population ageing in the 21st century will exceed that of the previous century. The number of people aged 60 years and over has tripled since 1950 and reached 600 million in 2000 and surpassed 700 million in 2006. It is projected that the combined senior and geriatric population will reach 2.1 billion by 2050. Countries vary significantly in terms of the degree and pace of ageing, and the UN expects populations that began ageing later will have less time to adapt to its implications.
Biogerontology is the sub-field of gerontology concerned with the biological aging process, its evolutionary origins, and potential means to intervene in the process. The term "biogerontology" was coined by S. Rattan, and came in regular use with the start of the journal Biogerontology in 2000. It involves interdisciplinary research on the causes, effects, and mechanisms of biological aging. Biogerontologist Leonard Hayflick has said that the natural average lifespan for a human is around 92 years and, if humans do not invent new approaches to treat aging, they will be stuck with this lifespan. James Vaupel has predicted that life expectancy in industrialized countries will reach 100 for children born after the year 2000. Many surveyed biogerontologists have predicted life expectancies of more than three centuries for people born after the year 2100. Other scientists, more controversially, suggest the possibility of unlimited lifespans for those currently living. For example, Aubrey de Grey offers the "tentative timeframe" that with adequate funding of research to develop interventions in aging such as strategies for engineered negligible senescence, "we have a 50/50 chance of developing technology within about 25 to 30 years from now that will, under reasonable assumptions about the rate of subsequent improvements in that technology, allow us to stop people from dying of aging at any age". The idea of this approach is to use presently available technology to extend lifespans of currently living humans long enough for future technological progress to resolve any remaining aging-related issues. This concept has been referred to as longevity escape velocity.
In law, medicine, and statistics, cause of death is an official determination of the conditions resulting in a human's death, which may be recorded on a death certificate. A cause of death is determined by a medical examiner. In rare cases, an autopsy needs to be performed by a pathologist. The cause of death is a specific disease or injury, in contrast to the manner of death, which is a small number of categories like "natural", "accident", "suicide", and "homicide", each with different legal implications.
Strategies for engineered negligible senescence (SENS) is a range of proposed regenerative medical therapies, either planned or currently in development, for the periodic repair of all age-related damage to human tissue. These therapies have the ultimate aim of maintaining a state of negligible senescence in patients and postponing age-associated disease. SENS was first defined by British biogerontologist Aubrey de Grey. Many mainstream scientists believe that it is a fringe theory. De Grey later highlighted similarities and differences of SENS to subsequent categorization systems of the biology of aging, such as the highly influential Hallmarks of Aging published in 2013.
Enquiry into the evolution of ageing, or aging, aims to explain why a detrimental process such as ageing would evolve, and why there is so much variability in the lifespans of organisms. The classical theories of evolution suggest that environmental factors, such as predation, accidents, disease, and/or starvation, ensure that most organisms living in natural settings will not live until old age, and so there will be very little pressure to conserve genetic changes that increase longevity. Natural selection will instead strongly favor genes which ensure early maturation and rapid reproduction, and the selection for genetic traits which promote molecular and cellular self-maintenance will decline with age for most organisms.
The following outline is provided as an overview of and topical guide to life extension:
Suresh Rattan is a biogerontologist – a researcher in the field of biology of ageing, biogerontology.
Ageing is the process of becoming older. The term refers mainly to humans, many other animals, and fungi, whereas for example, bacteria, perennial plants and some simple animals are potentially biologically immortal. In a broader sense, ageing can refer to single cells within an organism which have ceased dividing, or to the population of a species.
The International Day of Older People is observed on October 1 each year.
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.
Senescence-associated secretory phenotype (SASP) is a phenotype associated with senescent cells wherein those cells secrete high levels of inflammatory cytokines, immune modulators, growth factors, and proteases. SASP may also consist of exosomes and ectosomes containing enzymes, microRNA, DNA fragments, chemokines, and other bioactive factors. Soluble urokinase plasminogen activator surface receptor is part of SASP, and has been used to identify senescent cells for senolytic therapy. Initially, SASP is immunosuppressive and profibrotic, but progresses to become proinflammatory and fibrolytic. SASP is the primary cause of the detrimental effects of senescent cells.
The Lifespan Extension Advocacy Foundation (LEAF) is a non-profit organization with mission to support fundamental research on the main mechanisms of aging and age-related diseases and educate the public on the possibility of bringing aging under medical control in order to prevent, postpone and cure age-related diseases. It was founded in 2014 and is based in New York City, New York, USA.
This timeline lists notable events in the history of research into senescence or biological aging, including the research and development of life extension methods, brain aging delay methods and rejuvenation.
Council for Public Health and the Problems of Demography is a non-governmental nonprofit organization of Russia, that deals with such problems as alcoholism, tobacco smoking and age-related problems. Methods of work: researching the problem, drawing attention to the problem of society and state structures in all possible ways, developing and promoting possible solutions, interacting with the media and state structures, tracking the dynamics of the situation.
Vladimir Korenchevsky was a Russian-British pathologist, gerontologist, pharmacologist, and bacteriologist.
