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Theoretical Perspectives on Aging By: Cody Harman TRMT 392 Special Topics: Seniors David Robinson, PhD. May 17, 2010

Theoretical Perspectives on Aging

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Page 1: Theoretical Perspectives on Aging

Theoretical Perspectives on Aging

By: Cody Harman

TRMT 392

Special Topics: Seniors

David Robinson, PhD.

May 17, 2010

Page 2: Theoretical Perspectives on Aging

Contents1. Overview of Aging Theories

2. Overview of Aging Theories

3. Overview of Aging Theories

4. Overview of Aging Theories

5. The Beginnings of Aging Theory

6. Medawar’s Theory

7. Medawar’s Theory

8. Programmed Aging Theory

9. Non-Programmed Aging Theory

10. Physiological System Theory

11. Interconnectedness of Aging factors

12. My Opinion

13. References

Page 3: Theoretical Perspectives on Aging

Overview of aging theories

• Programmed Aging

– Theories that posit that the human condition is a ``programmed`` process

– According to the Programmed approach, the inherent repair and renew processes of the human body means that without genetic purpose for aging, our bodies could live without aging.

Page 4: Theoretical Perspectives on Aging

Overview of aging theories

– “...aging and death, according to this theory, are not a result of wear and tear or exposure, but are a programmed, natural and necessary part of genetics. In short, we are programmed to age and die. “(Stibich, 2007)

– Evidence for programmed aging is shown by many things, including the average age of death within a species (elephants around 70, people average 80 years) (Stibich, 2007)

Page 5: Theoretical Perspectives on Aging

Overview of aging theories

• Non-Programmed Aging– Theories that posit ideas of aging due to issues of

wear and tear, not through purposeful genetic programming

– Wear and tear theories are based on older, less developed ideas of evolutionary mechanics.

– Also called passive or non-adaptive, these theories contend that aging is actually adverse to populations

(Azinet LLC, 2010)

Page 6: Theoretical Perspectives on Aging

Overview of aging theories

• Physiological System Theories– Theories which suggest that aging is not the result

of either programmed or passive systems, but the result of failures in certain body systems causing bodily harm

– Physiological theories actually have influence from basic cellular deterioration theory, as well as the inter-connectedness of different biological systems in the human body

(Lakehead Education, 2005)

Page 7: Theoretical Perspectives on Aging

The Beginning of Aging Theory

• August Weismann, German evolutionary biologist, suggested a Programmed Death Theory. Programmed Death suggested that death is an important and required step in Darwinian evolution. Without death, younger (more evolved) members of a species would be required to contend for sustenance with older (less evolved) species members. This theory is supported in basic theory by modern advances in evolutionary mechanics. (Azinet LLC, 2009)

• Darwin`s On the Origin of Species, changed the entire conversation regarding aging. Prior to it`s publication, aging was believed to be part of the design of a species. No explanation was needed, as general opinion was that a creator designed the species. After publication, Darwin spoke of aging, saying “...there must be some hidden benefit to a limited life span that compensated for its otherwise adverse nature...” (Azinet LLC, 2009)

Page 8: Theoretical Perspectives on Aging

Medawar’s Theory

• Medawar's Hypothesis on Mammal Aging– One of the earliest theories regarding the relatedness of

population size and age. Combined ideas from both Weisman and Darwin.

“Medawar proposed that even if an animal did not age, that is, did not have an increased probability of death as a function of age, the numbers of adult animals of any given age would decrease exponentially because of deaths due to other causes such as predators, environmental conditions, etc. Some constant percentage of the animals of any given age would be killed in any given time period. As a metaphor, he used the random breaking and replacing of test tubes. If, in a lab with hundreds of test tubes, when a test tube is broken it is replaced with a new (age = 0) test tube, then after a while the number of test tubes of a given age in the test tube population will decline exponentially with age.”

(Azinet LLC, 2009)

Page 9: Theoretical Perspectives on Aging

Medawar’s Theory

Page 10: Theoretical Perspectives on Aging

Programmed Aging Theory

• Error Theory

– Error Theory suggests that aging is not a process of DNA, but actually RNA errors that result from poor transmission during the copying process of cell splitting

– This incomplete copy therefore cannot function as the original cell did, causing cellular breakdowns, deterioration, and eventually death in the host

(Lakehead Education, 2005)

Page 11: Theoretical Perspectives on Aging

Non-Programmed Aging Theory

• Wear and Tear Theory

– Suggests that the human body is similar to a machine, and is susceptible to wear and tear in much the same way that a car is (Azinet LLC, 2010)

– Damage is caused by toxins, radiation, ultra violet light, and other environmental influences (Stibich, 2007)

Page 12: Theoretical Perspectives on Aging

Physiological System Theory

• Immunological Theory– Suggests that aging is not a process, but more

accurately a disease of the immune system

– Immune system’s antibodies, which are supposed to help protect our systems

– Antibody production peaks during adolescence, and decreases from this early peak

– As antibody systems change over time, the body has trouble telling apart required cells from mutant cells. This effectively makes the human immune system it’s own enemy

(Lakehead Education, 2005)

Page 13: Theoretical Perspectives on Aging

Interconnectedness of Aging factors

Image taken from Innovita Research (http://www.innovitaresearch.org/news/res/02071901_01.jpg)

Page 14: Theoretical Perspectives on Aging

My Opinion

Upon reading all of the material, researching, and compiling information, I have developed my own opinions regarding aging theory. While many of the theories in each of the categories (programmed, passive, physiological) are developed to offer an alternative to other theories, I have an opinion that takes influence from all of the categories, and is an attempt at looking more holistically at the aging process. The Error theory’s suggestion of RNA replication errors offers a scientifically supported explanation of why cellular breakdown occurs, and can also explain why it occurs more rapidly as our bodies age. The Wear and Tear theory’s consideration of external influences in not cellular mutation is suggested as a replacement to Error theory, but I feel that both Error, and Wear and Tear theories are different paths to reach the same destination. I feel that cellular mutations the cause deterioration are not the result of one or the other, but a combination of RNA errors and external influences. Further, The Immunological system theory`s suggestion that immunity breakdowns cause aging is, I think, a result of the Programmed and Passive theories. If the cellular mutations experienced in these theories did not occur, then arguably the Immune systems functions would still occur in the same way as they did during adolescence. This would lead us to not age in the same way we age now. We would age, but functionally, we would not deteriorate.

Page 15: Theoretical Perspectives on Aging

Further explanation and understanding

• Aubrey de Grey, a biogerontologist from Cambridge, is a proponent of “curing” humanity of age related deaths. In this video he discusses the potential to reverse aging. Click his picture to open the video.

Page 16: Theoretical Perspectives on Aging

References

Azinet LLC. (2010). Wear and tear theories of aging. Retrieved from http://www.programmed-aging.org/theories/wear_and_tear.html

Azinet LLC. (2009). Medawar's hypothesis on mammal aging. Retrieved from http://www.programmed-aging.org/theories/medawar_hypothesis.html

Azinet LLC, (2009). programmed aging theory information weismann's programmed death theory. Retrieved from http://www.programmed aging.org/theories/weismann_programmed_death.html

Azinet LLC, (2009). Darwin on aging theory. Retrieved from http://www.programmed-aging.org/theories/darwin_evolution.html

Lakehead Education, Initials. (2005). Biological theories of aging. Informally published manuscript, Gerontology, Lakehead University, Thunder BAy , Ontario. Retrieved from http://flash.lakeheadu.ca/~mstones/Biological%20theories%20of%20aging.pdf

Stibich, Mark. (2007, 3 28). Programmed theories of aging. Retrieved from http://longevity.about.com/od/researchandmedicine/p/age_programmed.htm

Stibich, Mark. (2007, March 28). Wear and tear theory of aging. Retrieved from http://longevity.about.com/od/researchandmedicine/p/wear_tear.htm