Aging Theories

Question 1

What is senescence?

Answer 1

gradual deterioration as a function of age seen in humans and other organisms that reproduce more than once.

Question 2

What are age-related diseases and conditions?

Answer 2

cancer, heart disease, stroke, alzheimer’s disease.

muscle/bone deterioration, decline in reproductive ability, reduced immunity response, sensory loss.

Question 3

what is considered the life span?

Answer 3

the internally determined amount of time a member of a species population can be expected to live.

Question 4

What is Charles Darwins 1859 theory?

Answer 4

current species are descendants of earlier/different species. the process of evolution has been operating on earth for billions of years.

Question 5

what is the evolution process?

Answer 5

caused by organisms with favourable design characteristics having a larger probability of producing adult descendants with those traits than an otherwise identical individual lacking the trait

Question 6

What are three concepts regarding the relationship between senescence and evolution?

Answer 6

a. the evolutionary force towards surviving and reproducing does not vary with age (darwins theory)
b. the evolutionary force declines following a species and population specific age, but there is no disadvantage to living longer.
c. there is evolutionary force toward achieving but not exceeding a species and population specific optimum life span. A longer internally determined life span creates evolutionary disadvantage.

Question 7

What do damage theories (aka error theories) suggest?

Answer 7

senescence is ultimately caused by a particular damage process that is more general than disease-specific processes, thus causing many or all age-dependent manifestations.

Question 8

what are suggested damage processes from error theories?

Answer 8

oxidation, free radicals, heat shock proteins, mechanical wear/tear, accumulation of chemical damage due to metabolism or other life processes, accumulating damaging mutations, entropy or other fundamental physical or chemical limitations

Question 9

what do damage theories fail to explain?

Answer 9

life span differences between biochemically and physically similar species with similar exposure to the damage process; they also fail to deal with repair issue.

Question 10

who are two biologists that proposed evolutionary nonprogrammed aging theories?

Answer 10

Sir Peter Medawar (1952)
George C. Williams (1957)

Question 11

what aging theory did Sir Peter Medawar propose?

Answer 11

a population oriented evolution mechanics concept suggesting that aging had little impact on wild population because its affects would be masked by mortality from external causes.

Question 12

what evolutionary nonprogrammed aging theory did George C. Williams suggest?

Answer 12

that fitness adverse affects of aging occurred too early in life to have a negligible effect on mammal population.
- aging therefore must provide some evolutionary benefit to compensate for the relatively small early fitness loss.

Question 13

what theory suggests that mutations that only adversely affect later life could occur to be somewhat retained?

Answer 13

mutation accumulation theory

Question 14

what is pleiotropy?

Answer 14

defects in single gene can affect multiple traits of an organism

Question 15

what theory suggests that pleiotropy could cause aging to be unalterably linked to some beneficial trait, causing a net benefit that offsets minor disadvantage of aging?

Answer 15

antagonistic pleiotropy theory

Question 16

what theory suggests that organism repair activities consume substantial food and energy resources?

Answer 16

disposable soma theory: an organism could therefore be designed to reduce repair at a species-specific age in favour of using the resources to enhance reproduction in younger individuals

Question 17

what are issues with evolutionary nonprogrammed aging theories?

Answer 17

no scientific agreement on particular theory and they compete with each other;
require modifications to darwins concepts;
critics suggest logical issues and conflicts with various observations in connection with each theory.

Question 18

what are the evolutionary programmed aging theories?

Answer 18

group selection;
kin selection;
small group selection;
evolvability theories

Question 19

what is the theory that natural selection favours some groups over others, leading to the evolution of traits that are group advantageous?

Answer 19

group selection

Question 20

what is the evolution process that favours the reproductive success of an organism’s relatives, even at a cost to the organism’s own survival and reproduction?

Answer 20

kin selection

Question 21

what theory states that traits that favour a small isolated group can evolve despite causing a disadvantage for individual members?

Answer 21

small group selection

Question 22

what theory states a trait that increases population’s ability to adapt can evolve even if it results in some cost for individuals?

Answer 22

evolvability theories

Question 23

why were evolutionary programmed aging theories developed?

Answer 23

in effort to explain other apparent conflicts between evolution theory and observations such as animal altruism.

Question 24

how does senescence benefit a population?

Answer 24

increasing evolvability by removing older, less evolved members that would otherwise compete for resources;
enhance spread of beneficial mutations via kin selection;
limit overpopulation and consequent population crashes;
enhance evolution of intelligence and immunity

Question 25

what is the programmed vs nonprogrammed aging controversy?

Answer 25

disagreement regarding arcane details of evolution process. the degree to which survival or extinction of a population can offset individual advantage or disadvantage.

Question 26

What discoveries support population-oriented theories and programmed aging?

Answer 26

genetic discoveries: large phenotypic changes due to selective breeding; suggests short-term disadvantage would override long-term benefit.
-evolution is concerned with combined net effect of all of an organisms traits, thus raising issues with inter-trait linkage.

phenotypic linkage: process must be incremental/time consuming because complementary changes must occur in other areas.

Question 27

how do simple damage theories relate to medical implications of aging theories?

Answer 27

based off of darwins evolutionary mechanics: altering aging is impossible because evolution has not already done so.

Question 28

how do nonprogrammed theories relate to medical implications of aging theories?

Answer 28

no potentially treatable common factor behind age related diseases and conditions; species have specific complex repair mechanisms that just allow support of life span needed.

Question 29

how do programmed theories relate to medical implications of aging theories?

Answer 29

common biological mechanism schedules aprox. simultaneous appearance of symptoms, by down regulating repair mechanisms;

Question 30

what do externally regulated programmed aging theories suggest?

Answer 30

common program is in turn influenced by detection of certain conditions such as famines, overcrowding, predation that would logically affect the optimum life span needed by species.

Question 31

what are the most promising strategies that could be tested on humans for effects on life span?

Answer 31

dietary interventions
drugs that inhibit growth hormone/IGF-Iaxis
drugts that inhibit mTOR0S6K pathway
drugs that activate AMPK

Question 32

what is the consensus of life span extension research?

Answer 32

aging interventions will delay and prevent onset of many chronic conditions
essential pathways have been identified and behavioural, dietary, and pharmacological approaches have emerged.

Question 33

what are examples of anti-aging medicine?

Answer 33

cosmetic-face lift, Botox, ect.
healthy living: diets, PA, treatments intended to extend healthy portion of life
life span extension: uses treatment focused on increasing maximum human life span, delaying aging manifestations

Question 34

what are two major initiatives that impact lifespan extension?

Answer 34

telomerase activation
hormone replacement theory

Question 35

how does telomerase activation affect life span extension?

Answer 35

shortening of telomeres long been considered aging factor;
length is considered age indicator
telomerase is naturally occurring enzyme that acts to repair telomeres: activators oral agents that increase production of telomerase

Question 36

What is the relationship between dependence and age? how would it appear on a graph?

Answer 36

younger=more dependent
middle= independent
older= more dependent.
appears as a U shape.

Question 37

how would you define successful aging?

Answer 37

a decreased likelihood of acquiring disease, maintanence of functional capacity, and active participation in life events

Question 38

how does ageism affect older adults?

Answer 38

reinforces stereotypes, portray snegative attitudes towards older adults, and implements unfair treatment as a result of their age.

Question 39

what are some common conditions associated with aging?

Answer 39

cancer, CDV disease, Heart disease, the five basic senses (visual, auditory primarily).

Question 40

what is the difference between lifespan and longevity

Answer 40

Life span refers to the maximum potential of the human species, or
how long it is theoretically possible for a person to live.
Longevity refers to the number of years a person in a particular
society or country can expect to live

Question 41

explain the population-oriented theories regarding the evolutionary processes:

Answer 41

Darwin’s theory: the evolution process is caused by organisms with favourable design characteristics (traits) having a larger probability of producing adult descendants with those characteristics than an otherwise identical individual lacking the trait.
Error theories: senescence is ultimately caused by a particular damage process that is more general than disease-specific processes, thus causing many or all age-dependent manifestations (oxidation, free radicals, heat shock proteins, mechanical wear and tear…). Medawar: Proposed a population oriented evolution mechanics
concept suggesting that again had little impact on a wild population (effects would be masked by mortality from external causes). Williams: Fitness-adverse effects of aging (such as decreases in strength) occurred too early in life to have a negligible effect on mammal population (suggested that aging therefore must provide some evolutionary benefit to compensate for the relatively small early fitness loss).
Mutation accumulation theory: mutations that only adversely affect later in life could occur and be somewhat retained.
Antagonistic pleiotropy theory: Pleiotropy
could cause aging to be unalterably linked to some beneficial trait, causing a net benefit that offsets the minor disadvantage of aging. Disposable soma theory: Organism repair activities consume substantial food and energy sources. An organism could therefore be designed to reduce repair at a species-specific age (causing fitness loss only in a few surviving older individuals) in favour of using the resources to enhance reproduction in younger individuals.

Question 42

what do programmed theories of aging suggest?

Answer 42

an organism can evolve a trait that benefitted the survival and growth of a population at the expense of individual members.
ex: group selection, kin selection, small group selection, evolvability theories.
Programmed aging theories suggest that a common biological
mechanism is responsible for diverse aging manifestations and therefore
senescence, per se, is a treatable condition. Some programmed aging
theories suggest that physical activity and caloric restriction are detected by
mammals and act to lengthen genetically programmed life span.

Question 43

what are examples of anti-aging medicine?

Answer 43

cosmetic anti-aging treatments- face lifts, botox, etc.
health aging- diets, exercise, treatments intended to extend healthy and active portions of life
life span extension- treatments focused on increasing maximum life span and generally delaying aging manifestations: telomerase activation, bioidentical hormone replacement therapy.

Question 44

what are some potential consequences to extending life span?

Answer 44

affect social security, health insurance, pensions, annuities, retirement age, term limits and other practicalities. increase income inequality, also unethical.