Causes of Aging

I'm lead to wonder why it is that I'm getting older. What is going on here exactly, and what can I do about it? As it turns out, nobody knows for sure.

Wikipedia:

At present, the biological basis of aging is unknown. Most scientists agree that substantial variability exists in the rates of aging across different species, and that this to a large extent is genetically based. In model organisms and laboratory settings, researchers have been able to demonstrate that selected alterations in specific genes can extend lifespan (quite substantially in nematodes, less so in fruit flies, and even less in mice). Nevertheless, even in the relatively simple organisms, the mechanism of aging remain to be elucidated. Because the lifespan of even the simple lab mouse is around 3 years, very few experiments directly test specific aging theories (most of the evidence for the ones listed below is correlative).

The National Institute on Aging currently funds an intervention testing program, whereby investigators nominate compounds (based on specific molecular aging theories) to have evaluated with respect to their effects on lifespan and age-related biomarkers in outbred mice [30]. Previous age-related testing in mammals has proved largely irreproducible, because of small numbers of animals, and lax mouse husbandry conditions. The intervention testing program aims to address this by conducting parallel experiments at three internationally recognized mouse aging-centers, the Barshop Institute at UTHSCSA, the University of Michigan at Ann Arbor and the Jackson Lab. While the hypotheses below reflect some of the current direction in biological aging research, none of them is accepted as a "theory" in the sense of the "theory of gravity" or "theory of relativity".

Telomere Theory
Telomeres (structures at the ends of chromosomes) have experimentally been shown to shorten with each successive cell division. Shortened telomeres activate a mechanism that prevents further cell multiplication. This may be an important mechanism of aging in tissues like bone marrow and the arterial lining where active cell division is necessary. Importantly though, mice lacking telomerase do not show a dramatically reduced lifespan, as the simplest version of this theory would predict.

Reproductive-Cell Cycle Theory
The idea that aging is regulated by reproductive hormones that act in an antagonistic pleiotropic manner via cell cycle signaling, promoting growth and development early in life in order to achieve reproduction, but later in life, in a futile attempt to maintain reproduction, become dysregulated and drive senescence (dyosis). At the same time, castrated animals, although living somewhat longer, still experience senescence, even in the absence of reproductive hormones.

Wear-and-Tear Theory
The very general idea that changes associated with aging are the result of chance damage that accumulates over time.

Somatic Mutation Theory
The biological theory that aging results from damage to the genetic integrity of the body’s cells.

Error Accumulation Theory
The idea that aging results from chance events that escape proof reading mechanisms, which gradually damages the genetic code.

Evolutionary Theories
See Theories of aging in Senescence. These are by far the most theoretical; however, their usefulness is somewhat limited as they do not provide readily testable biochemically based interventions.

Accumulative-Waste Theory
The biological theory of aging that points to a buildup of cells of waste products that presumably interferes with metabolism.

Autoimmune Theory
The idea that aging results from an increase in autoantibodies that attack the body's tissues. A number of diseases associated with aging, such as atrophic gastritis and Hashimoto's thyroiditis, are probably autoimmune in this way. While inflammation is very much evident in old mammals, even SCID mice in SPF colonies still senescence.

Aging-Clock Theory
The theory that aging results from a preprogrammed sequence, as in a clock, built into the operation of the nervous or endocrine system of the body. In rapidly dividing cells the shortening of the telomeres would provide just such a clock. This idea is indirect contradiction with the Evolutionary Based Theory of Aging.

Cross-Linkage Theory
The idea that aging results from accumulation of cross-linked compounds that interfere with normal cell function.

Free-Radical Theory
The idea that free radicals (unstable and highly reactive organic molecules, also named reactive oxygen species or oxidative stress) create damage that gives rise to symptoms we recognize as aging.

Mitohormesis
It has been known since the 1930s that restricting calories while maintaining adequate amounts of other nutrients prevents aging across a broad range of organism. Recently, Michael Ristow has shown that this delay of aging is due to increased formation of free radicals within the mitochondria causing a secondary induction of increased antioxidant defence capacity.

Comments

[Zen]

Or it could just be that what goes up must come down.

[Melanie]

Why do we age? My thoughts on why we age are from a number of sources and not just one.
* First, I think we have a clock that ticks within our bodies cells and/or brain. We are all born aprox. 9 months after conception. We all grow to adulthood at the same time. All of our clocks at this age are running at the same speed.
* Second, I think the Accumulative-Waste Theory adds to our age. After we become adults we start to age a different rates of time. Diet and exercise determines how fast you age. My own theory is that hard water minerals collect in our bodies just like in a container/glass. That is why I drink pure distilled water. That is my hard water theory. Fountain of Youth.
* Third, I think disease has a part on aging. Everytime you get sick from a cold or the flu damages your cells. I think it is impossible to avoid getting sick from something.
* Fourth, we age for reasons besides those given above. Multiple reasons.

[Zen]

I think therefore I age.

[Melanie]

My Father once told me that your Body is similar to your Car.
Both give you mobility, get you from place to place. Both look good when they are new, but wear out, get dings, scrathes, scars, leak and rust. Both are built well but are designed to only last a certain amount of time. Some owners can make their vehicles/body last longer buy taking care of them.

Last of all when your vehicle no longer works the tow truck/hertz comes and takes your Vehicle/Body to the junkyard/graveyard. After you get rid of your old car you buy a New Vehicle. Varooooom, Varoooom