Timeline of Discoveries in the Science of Aging

A History on The Biology of Aging
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June, 16,1825 - Benjamin Gompertz Finds that Mortality Increases Exponentially with Age Benjamin Gompertz Finds that Mortality Increases Exponentially with Age
Methods: Empirically deriving the death rate from demographic data of England
Institution: The Royal Society

- 1892, 01, January August Weismann Proposes a Difference Between Germ Line and Somatic Cells August Weismann Proposes a Difference Between Germ Line and Somatic Cells
Methods: By drawing upon current research and contrasting it to the current dogma under Darwin's theory of pangenises.
Institution: University of Freiburg-in-Baden

November, 01,1934 - Clive McCay Discovers that Calorie Restriction Extends Life-Span in Rats Clive McCay Discovers that Calorie Restriction Extends Life-Span in Rats
Methods: Feeding one group of rats a lower calorie diet than another group, and observing that the under-fed group lived longer
Institution: Cornell University

- 1952, 01, January Peter Medawar proposes that aging evolved into existence since the force of natural selection diminishes after reproduction Peter Medawar proposes that aging evolved into existence since the force of natural selection diminishes after reproduction
Institution: University College London

July, 1,1956 - Denham Harman proposes the free radical theory of aging Denham Harman proposes the free radical theory of aging
Methods: Harman's logic proceeds from three observations: (1) irradiation causes premature aging; (2) irradiation creates oxygen radicals, which may mediate its effects; and (3) cells produce oxygen radicals under normal conditions. From these premises, he theorized that aging could be caused by endogenously generated oxygen radicals.
Institution: University of California - Berkeley

- 1957, 26, February George C. Williams expands on the theory of antagonistic pleiotropy George C. Williams expands on the theory of antagonistic pleiotropy
Methods: By defining assumptions and providing set expectations
Institution: Michigan State University

May, 15,1961 - Hayflick and Moorhead Characterize Cellular Senescence in Primary Human Cells Hayflick and Moorhead Characterize Cellular Senescence in Primary Human Cells
Methods: The authors characterized 25 strains of human cells over the course of long-term growth in culture.
Institution: Wistar Institute

- 1963, 15, February Leslie Orgel Proposes the "Error Catastrophe" Theory of Aging Leslie Orgel Proposes the "Error Catastrophe" Theory of Aging
Methods: Orgel hypothesizes that translation errors could decrease the fidelity of translation, setting in motion a vicious cycle ultimately causing a critical failure of the gene expression machinery; he further proposes that the resulting loss of cell viability could be a contributing factor in the aging process.
Institution: University of Cambridge

March, 01,1965 - Leonard Hayflick proposes the Cellular Theory of Aging based on the limited replicative lifespan of primary human cells Leonard Hayflick proposes the Cellular Theory of Aging based on the limited replicative lifespan of primary human cells
Methods: Normal diploid cells were serially passaged in culture until they stopped dividing
Institution: Wistar Institute

- 1970, 19, September David and Harriet Gershon Find Accumulation of Non-active Enzymes in Older Nematodes David and Harriet Gershon Find Accumulation of Non-active Enzymes in Older Nematodes
Methods: Using immunological techniques to detect catalytically altered or inactive enzyme molecules in the nematode Turbatrix aceti
Institution: Israel Institute of Technology

March, 12,1982 - Richard Weindruch finds that adult mice on dietary restriction live 20% longer and have lower cancer rates Richard Weindruch finds that adult mice on dietary restriction live 20% longer and have lower cancer rates
Methods: By feeding a control group a normal diet and another group a high nutrient calorie restricted diet and observing which lived longer
Institution: University of California at Los Angeles

- 1983, 15, November Anthony Cerami proposes the Maillard Reaction theory of aging stating that DNA accumulates damage due to nonenzymatic modification from sugars Anthony Cerami proposes the Maillard Reaction theory of aging stating that DNA accumulates damage due to nonenzymatic modification from sugars
Methods: By incubating isolated DNA with high levels of glucose at 37 degrees Celsius, or body temperature, and recording changes in DNA through spectroscopy
Institution: Rockefeller University

February, 02,1984 - Michael R. Rose asserts that senescence can be postponed by natural selection Michael R. Rose asserts that senescence can be postponed by natural selection
Methods: Reviewing past articles
Institution: Dalhousie University

- 1985, 01, December Carol W. Greider and Elizabeth H. Blackburn Discover A Specific Telomere Terminal Transferase Later Known as Telomerase Carol W. Greider and Elizabeth H. Blackburn Discover A Specific Telomere Terminal Transferase Later Known as Telomerase
Methods: By obtaining extracts of Tetrahymena during macronuclear development when new telomeres are generated
Institution: University of California - Berkeley

January, 01,1986 - Robert M. Sapolsky, Lewis C. Krey, and Bruce S. McEwen Propose the Glucocorticoid Cascade Hypothesis of Aging Robert M. Sapolsky, Lewis C. Krey, and Bruce S. McEwen Propose the Glucocorticoid Cascade Hypothesis of Aging
Methods: Citing past research indicating that older mice release greater amounts of glucocorticoids in response to stress, and that this release precipitates a cascade effect of hypersecretion
Institution: The Salk Institute

- 1988, 05, February Thomas Johnson and David Friedman Define the AGE-1 gene Thomas Johnson and David Friedman Define the AGE-1 gene
Methods: By obtaining long-lived mutants of C. elegans and crossing them to screen which alleles resulted in longer lifespans
Institution: University of California - Irvine

September, 15,1993 - Cynthia Kenyon finds that mutations in daf-2 and daf-16 genes cause C. elegans worms to live over twice as long Cynthia Kenyon finds that mutations in daf-2 and daf-16 genes cause C. elegans worms to live over twice as long
Methods: By regulating the formation of a dauer state, and observing how long the daf-2 mutated strains lived compared to other strains.
Institution: University of California at San Francisco

- 1994, 01, December Brian K. Kennedy et al. Discover that the Daughter Cells of Old Yeast have Shorter Life-Spans than those of Younger Strains Brian K. Kennedy et al. Discover that the Daughter Cells of Old Yeast have Shorter Life-Spans than those of Younger Strains
Methods: By growing yeast and manipulating away their progeny, then counting how long both the first strain and the progeny lived
Institution: Massachusetts Institute of Technology

February, 10,1995 - Brian K. Kennedy et al. Find that SIR4-42 Extends the Life Span of Yeast by 30% and May Play a Key Role in Regulating Aging Brian K. Kennedy et al. Find that SIR4-42 Extends the Life Span of Yeast by 30% and May Play a Key Role in Regulating Aging
Methods: By culturing various strains of yeast under stressful conditions and analyzing the longest lived strains for key mutations
Institution: Massachusetts Institute of Technology

- 1997, 04, August Daniel E. Martìnez finds that Hydra do not show signs of Biological Aging Daniel E. Martìnez finds that Hydra do not show signs of Biological Aging
Methods: By keeping hydra alive for four years and plotting their mortality rates vs. that of similar sized organisms like Drosophila melanogaster (fruit fly)
Institution: Pomona College

January, 16,1998 - Andrea Bodnar, Michel Ouellette, et al. Find An Extension of Human Cell Life-Span with the Introduction of Telomerase Andrea Bodnar, Michel Ouellette, et al. Find An Extension of Human Cell Life-Span with the Introduction of Telomerase
Methods: By transfecting cells with vectors encoding the human telomerase catalytic subunit and noticing that the cells exceeded normal replicative lifespan
Institution: Geron

- 2003, 17, July Coleen Murphy et al. find genes downstream of daf-16 which regulate aging in C.elegans nematodes Coleen Murphy et al. find genes downstream of daf-16 which regulate aging in C.elegans nematodes
Methods: By comparing transcriptional profiles of long lived c.elegans mutants vs. wild-type and identifying genes that were upregulated or downregulated
Institution: University of California - San Francisco

August, 24,2003 - David A. Sinclair et al. Discover Three Classes of Molecules that Activate Sirtuins (Including Resveratrol) David A. Sinclair et al. Discover Three Classes of Molecules that Activate Sirtuins (Including Resveratrol)
Methods: By screening small molecule libraries for molecules which could modulate sirtuin activity
Institution: Harvard Medical School

- 2004, 01, November Norman E. Sharpless finds that expression of the Ink4a/Arf locus is a biomarker of aging Norman E. Sharpless finds that expression of the Ink4a/Arf locus is a biomarker of aging
Methods: Using PCR assays on the expression of cyclin-dependent kinase inhibitor family members to find variations in expression of the gene p16^INK4a
Institution: UNC Chapel Hill

January, 01,2004 - Norman Sharpless and Ronald Pinho Propose the Stem-Cell Theory of Aging Norman Sharpless and Ronald Pinho Propose the Stem-Cell Theory of Aging
Methods: By citing past evidence their reasoning follows that a cell with genomic instability will either undergo senescence/apoptosis, or proliferate into cancer, depending on the integrity and ability of various cell cycle check points.
Institution: UNC Chapel Hill

- 2005, 18, November Matt Kaeberlein et al. propose that the TOR and Sch9 kinases regulate longevity in yeast Matt Kaeberlein et al. propose that the TOR and Sch9 kinases regulate longevity in yeast
Methods: Large-scale analysis of 564 gene deletions which yielded 6 genes corresponding to the TOR and Sch9 pathways

July, 24,2006 - Andrea Bodnar Finds a Lack of Age-Associated Telomere Shortening in Long and Short Lived Sea Urchins Andrea Bodnar Finds a Lack of Age-Associated Telomere Shortening in Long and Short Lived Sea Urchins
Institution: Bermuda Institute of Ocean Sciences

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