Ex1 L3 - Theories of Aging Flashcards
What is a theory?
a scientifically acceptable general principle or body of principles offered to explain a phenomena
The scientific method is used to…
test hypotheses and ultimately develop theories
Theories tend to —— while hypotheses can —–
Theories tend to contradict each other while multiple hypotheses can be true at once
What is the programmed theory of aging?
- attempts to describe how evolution would favor aging
- suggested that aging was programmed into our genes (and everyone has the same ones)
- now discredited, does not consider environmental aspects
What is the evolutionary senescence theory of aging?
- natural selection fails to affect traits later in life
- genes and mutations that are good now have bad impacts later in life do not affect reproductive success, so they can “escape” natural selection
- currently most widely accepted theory, but does not account for psychosocial, activity, etc.
What are some sub-theories that fit under the overarching evolutionary senescence theory?
- mutation accumulation theory
- antagonistic pleiotropy theory
- disposable soma theory
What is mutation accumulation theory?
- by Medawar
- deleterious late-life genes and mutations will still be passed on to future generations
- they accumulate over time
What is antagonistic pleiotropy theory?
- by Williams
- also called pay later theory
- genes that increase the odds of successful reproduction in early life may be harmful in later life (benefit now, pay later)
- good example is proliferation of the uterine lining - good for pregnancy, but bad for uterine cancer
What is the disposable soma theory?
- by Kirkwood
- hazardous environments favor early reproduction and a short lifespan
- allocation of all resources can go to reproduction even if it leads to death
What is the genome maintenance theory of aging?
humans have longer lifespans because we are more able to repair our genome than other species
What is replicative senescence theory?
all cells have a Hayflick limit (the limit of times they can divide before telomeres get too short and they stop dividing)
What is the oxidative damage/free radical theory of aging?
toxic byproducts of normal metabolism cause damage and contribute to disease
What are the three psychosocial theories of aging?
- disengagement theory
- activity theory
- continuity theory
What is disengagement theory of aging?
- natural, acceptable withdrawal of older adults from society (behavioral change)
- first social theory of aging
What is the activity theory of aging?
- successful aging is more likely when older adults remain physically active and socially active
