Once they wear out, they can no longer function correctly.
It is sometimes called simple deterioration theory or fundamental limitation theory.
It’s one of many theories on aging that continue to emerge.
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Some view aging as a more intentional process.
It also reviews different aging theories that compare with it.
The wear-and-tear theory is just one.
Each theory has evidence for and against it.
There are two primary categories of aging: programmed theories and error theories.
Programmed theories of agingbelieve that aging is a normal process, just as puberty is a normal developmental process.
These include:
Wear-and-tear theory of aging falls into this latter category of error theories.
Programmed theories view aging as a natural process that follows a “healthy” cycle in the body.
Error theories look at aging as an accident and “problem” to be solved.
The differences go far beyond biology and become a philosophical discussion.
Basic Tenets of Wear-and-Tear Theory
The wear-and-tear theory basically states that bodies wear out after time.
Causes of Wear-and-Tear Damage
A wide range of internal and external factors can damage body systems.
Exposure to radiation, toxins, and ultraviolet light can damage genes.
The effects of the body’s own functioning can also cause damage.
When the body metabolizes oxygen, free radicals are produced that can cause damage to cells and tissues.
As these cells are lost, function eventually will be lost.
There is evidence both for and against this theory.
Matches common perceptions of aging.
Fits law of entropy.
Many bodily processes decline with aging.
Cells are well-equipped to repair damage.
Humans and other organisms grow stronger from youth to maturity.
Organisms vary widely in lifespan rather than all following the same pattern.
Supporting Evidence
The wear-and-tear theory of aging fits most closely with a perceived sense of aging.
Visually, there are structural changes with age in human skin and bones.
On a cellular level, there are a number of functions which decline with age.
Even with a good diet, cells have a decreased ability to absorb nutrients with age.
DNA is equipped with DNA-repair genes (such astumor suppressor genes) which work to repair genetic damage.
Another argument against the wear-and-tear theory notes that organisms in their growth phase become stronger and stronger.
They build strength and resilience with age.
They are able to repair and replace most broken parts themselves.
Finally, there are some circumstances in which wear-and-tear actually extends life expectancy.
Yet another argument comes about when looking at the biochemical nature of the body.
Why do lifespans vary so much between different species of animals?
Why do some whales live almost twice as long as humans?
What Does This Mean for You?
A Word From Verywell
Find ways to make living a healthy life fun.
However, aging research continues to seek answers for why people age and die.
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