Gerontology (from Greek: γερο, gero, "old age"; and λόγος, logos, "speech" lit. "to talk about old age") 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 disease of the elderly.
Gerontology includes these and other endeavors:
- studying physical, mental, and social changes in people as they age;
- investigating the aging process itself (biogerontology);
- investigating the interface of normal aging and age-related disease (geroscience);
- investigating the effects of our aging population on society, including the fiscal effects of pensions, entitlements, life and health insurance, and retirement planning;
- applying this knowledge to policies and programs, including a macroscopic (i.e. government planning) and microscopic (i.e. running a nursing home) perspective.
The multidisciplinary focus of gerontology means that there are a number of sub-fields, as well as associated fields such as psychology and sociology that also cross over into gerontology. However, that there is an overlap should not be taken as to construe that they are the same. For example, a psychologist may specialize in early adults (and not be a gerontologist) or specialise in older adults (and be a gerontologist).
The field of gerontology was developed relatively late, and as such often lacks the structural and institutional support needed (for example, relatively few universities offer a Ph.D. in gerontology). Yet the huge increase in the elderly population in the post-industrial Western nations has led to this becoming one of the most rapidly growing fields. As such, gerontology is currently a well-paying field for many in the West.
- Main article: Life extension
Biogerontology, is the subfield of gerontology dedicated to studying the biological processes involved in aging. Some have looked to develop theories of the aging process, such as telomere shortening, the free radical theory, and the like. Some skeptics have worked to show that aging is a biological process that we are far from being able to control. Conservative biogerontologists who have only an intellectual interest in the aging process, like Leonard Hayflick, have predicted that the human life expectancy numbers will top out at about 85 (88 for females, 82 for males).
Biomedical gerontology, also known as experimental gerontology and life extension, is a sub discipline of biogerontology, that endeavors to slow, prevent, and even reverse aging in both humans and animals. Curing age-related diseases is one approach, and slowing down the underlying processes of aging is another. Most 'life extensionists' believe the human life span can be altered within the next century, if not sooner. 'Optimists' have predicted a changing human life span, though this has not yet been demonstrated.
Many biogerontologists take an intermediate position, emphasizing the study of the aging process as a means of mitigating aging-associated diseases, while denying that maximum life span can be altered (or denying that it is desirable to try).
Notable biomedical gerontologists
- Ana Aslan
- L. Stephen Coles - a key member of the Supercentenarian Research Foundation
- Alex Comfort - studied and popularized the biology of aging, while promoting life extension
- Michael Fossel
- Aubrey de Grey - originated the concept and theory of engineered negligible senescence
- Steven A. Garan
- Leonid Gavrilov - suggested the reliability theory of aging and longevity
- David Gems
- Leonard Guarente - proposed that sirtuins mediate the beneficial effects of caloric restriction 
- Denham Harman (born 1916) - developed the free radical theory of aging
- Robin Holliday - discovered "Holliday junctions" as homologous recombination; extensive work on testing the error catastrophe theory of aging; putforward the ideas about the role of DNA methylation and epimutations in aging.
- Thomas E. Johnson - discovered long-lived mutants of C elegans
- Matt Kaeberlein - discovered the anti-aging role of sirtuins  and proposed that the mammalian target of rapamycin (mTOR) mediates the beneficial effects of caloric restriction 
- Brian Kennedy - challenges the hypothesis that sirtuins mediate the beneficial effects of caloric restriction instead proposing that the mediator is the mammalian target of rapamycin (mTOR) 
- Cynthia Kenyon - quadrupled the lifespan of specimens of the small worm Caenorhabitis elegans by altering a single gene
- Thomas Kirkwood - developed the disposable soma theory, contributing to the evolutionary biogerontology
- Marios Kyriazis - proposed carnosine as a general anti-aging supplement, and disapproved the notion that cosmetics and beauty products form part of anti-aging medicine
- Linda Partridge
- Durk Pearson - mostly self-taught on biology research, published the book Life Extension
- Suresh Rattan - coined the terms gerontogenes and virtual-gerontogenes; is a pioneer of application of mild stress-induced hormesis as an aging modulatory strategy in human cells; and is the founding Editor-in-Chief of the journal "[Biogerontology]http://www.springer.com/life+sci/cell+biology/journal/10522".
- Michael R. Rose -- bred long-lived fruit flies, a founder of evolutionary biogerontology
- David Sinclair - proposed that resveratrol slows aging and mimics caloric restriction by activating Sirtuins 
- Roy Walford (June 29, 1924 San Diego, California – April 27, 2004) - an early advocate of caloric restriction
- Dominic Withers
Notable biogerotechnologists (business/applied)
Notable demographic gerontologists
- Jay Olshansky - a noted skeptic of life-extension claims
- Jean-Marie Robine - researched the Jeanne Calment case
- James Vaupel - lead the push for the internationalization of demographic data on the human life span
Notable non-biomedical biogerontologists
- Leonard Hayflick (born 1928) - discovered the Hayflick limit, asserts elimination of aging is neither possible nor desirable
- Raymond Pearl (3 June 1879 - 17 November 1940)
Social gerontology is a multi-disciplinary sub-field that specializes in studying or working with older adults.
Social gerontologists may have degrees or training in social work, nursing, psychology, sociology, demography, gerontology, or other social science professions. Gerontologists are responsible for educating, researching, and advancing the broader causes of older people by giving informative presentations, publishing books and articles that pertain to the aging population, producing relevant films and television programs, and producing new graduates of these various disciplines in college and university settings.
Because issues of life span and life extension need numbers to quantify them, there is an overlap with demography. Those that study the demography of the human life span are different than those that study the social demographics of aging.
- Dr. Alexis Abramson
- Vern Bengston
- James Birren
- Eileen Crimmins
- Linda George
- Pearl German
- Erdman Palmore - noted for the International Handbook on Aging
- Jon Pynoos
- K. Warner Schaie
- Alan Walker
History of Gerontology
It may be said that the history of gerontology begins with agriculture; prior to this the hunter-gatherer societies that existed could only support a marginal existence: food supply was short; frequent movement a necessity. These and other reasons meant that extremely few reached 'old age'. However, it could be argued that in a society with a life expectancy of 14 (such as 10,000 BC), being '40' was 'old'.
Things changed with the coming of agriculture. A more stable food supply and the lack of frequent movement meant that humans could now survive longer, and beginning perhaps around 4000 BC, a regular segment of the population began to attain 'old age' in places such as Mesopotamia and the Indus river valleys. Agriculture didn't simply bring a steady food supply; it also suddenly made older persons an economic benefit instead of a burden. Older persons could stay and watch the farm (or children); make pottery or jewelry, and perform social functions, such as story-telling (oral tradition, religion, etc). and teaching the younger generation techniques for farming, tool-making, etc.
After this change, the views of elder persons in societies waxed and waned, but generally the proportion of the population over 50 or 60 remained small. Note that in ancient Egypt, Pharaoh Pepi II was said to have lived to 100 years old. Certainly Ramses II lived to about 90; modern scientific testing of his mummy supports the written record. Ancient Greeks valued old persons for their wisdom (some reaching 80, 90, or 100 years old), while old age was devalued in Roman times.
In the medieval Islamic world, elderly people were valued by Muslim physicians. Avicenna's The Canon of Medicine (1025) was the first book to offer instruction for the care of the aged, foreshadowing modern gerontology and geriatrics. In a chapter entitled "Regimen of Old Age", Avicenna was concerned with how "old folk need plenty of sleep", how their bodies should be anointed with oil, and recommended exercises such as walking or horse-riding. Thesis III of the Canon discussed the diet suitable for old people, and dedicated several sections to elderly patients who become constipated.
The Canon of Medicine recognized four periods of life: the period of growth, prime of life, period of elderly decline (from forty to sixty), and decrepit age. He states that during the last period, "there is hardness of their bones, roughness of the skin, and the long time since they produced semen, blood and vaporal breath". However, he agreed with Galen that the earth element is more prominent in the aged and decrepit than in other periods. Avicenna did not agree with the concept of infirmity, however, stating: "There is no need to assert that there are three states of the human body—sickness, health and a state which is neither health nor disease. The first two cover everything."
The famous Arabic physician, Ibn Al-Jazzar Al-Qayrawani (Algizar, circa 898-980), also wrote a special book on the medicine and health of the elderly, entitled Kitab Tibb al-Machayikh or Teb al-Mashaikh wa hefz sehatahom. He also wrote a book on sleep disorders and another one on forgetfulness and how to strengthen memory, entitled Kitab al-Nissian wa Toroq Taqwiati Adhakira, and a treatise on causes of mortality entitled Rissala Fi Asbab al-Wafah. Another Arabic physician in the 9th century, Ishaq ibn Hunayn (died 910), the son of Hunayn Ibn Ishaq, wrote a Treatise on Drugs for Forgetfulness (Risalah al-Shafiyah fi adwiyat al-nisyan).
In medieval Europe on the other hand, during its Dark Ages, negative opinions of the elderly prevailed; old women were often burned at the stake as witches. However, with the coming of the Renaissance old age returned to favor in Europe, as persons such as Michelangelo and Andrea Doria exemplified the ideals of living long, active, productive lives.
While the number of aged humans, and the maximum ages lived to, tended to increase in every century since the 1300s, society tended to consider caring for an elderly relative as a family issue. It was not until the coming of the Industrial Revolution with its techniques of mass production that ideas shifted in favor of a societal care-system. Care homes for the aged emerged in the 1800s. Note that some early pioneers, such as Michel Eugene Chevreul, who himself lived to be 102 in the 1880s, believed that aging itself should be a science to be studied. The word itself was coined circa 1903 by Elie Metchnikoff.
It was not until the 1940s, however, that pioneers like James Birren began organizing 'gerontology' into its own field. Recognizing that there were experts in many fields all dealing with the elderly, it became apparent that a group like the Gerontological Society of America was needed (founded 1945).
In the 1950s to the 1970s, the field was mainly social and concerned with issues such as nursing homes and health care. However, research by Leonard Hayflick in the 1960s (showing that a cell line culture will only divide about 50 times) helped lead to a separate branch, biogerontology. It became apparent that simply 'treating' aging wasn't enough. Finding out about the aging process, and what could be done about it, became an issue.
The biogerontological field was also bolstered when research by Cynthia Kenyon and others demonstrated that life extension was possible in lower life forms such as fruit flies, worms, and yeast. So far, however, nothing more than incremental (marginal) increases in life span have been seen in any mammalian species.
Today, social gerontology remains the largest sector of the field, but the biogerontological side is seen as being the 'hot' side. Indeed, some have said that social gerontologists look to the past; biogerontologists look to the future.
- Journal of Applied Gerontology, ISSN: 1552-4523 (electronic) ISSN: 0733-4648 (paper), SAGE Publications
- Age and Aging, an international journal publishing refereed original articles on geriatric medicine and gerontology. Oxford University Press. 6 issues / 12 months. ASIN: B00006LAGZ ISSN:
- University of Southern California Davis School of Gerontology
- Fall Prevention Center of Excellence
- National Resource Center on Supportive Housing and Home Modification
- Aging Research Centre
- Biogerontologists (Gerontological Society of America)
- Biogerontology Resources
- Books on Gerontology published in 2007
- Careers in Aging
- Centre for Research on Ageing
- Gerontologists (DMOZ)
- Gerontology Research Group Site also has the official tables of known supercentenarians.
- Infogerontologia.com: recursos de gerontologia on-line (spanish)
- Journal of Gerontology Series A: Biological and Medical Sciences
- Journal of Gerontology Series B: Psychological and Social Sciences
- Gerontology Students Practice Resources
- Mechanisms of Aging
- Ouroboros Biomedical Gerontology Research News
- People in Biogerontology
- Senescence.info: An introduction to Biogerontology
- Vitae Institute non-profit devoted to biogerontological education and under-funded basic research
- Wayne State University Institute of Gerontology
- U.S. Administration on Aging
- Leibniz Institute for Age Research - Fritz Lipmann Institute (FLI)
-  Biogerontology
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