Why do we age?
The science and study of aging is called gerontology. There is no single cause for ageing and is a matter of intense research and debate. Several theories of ageing have been postulated. These are categorised in two ways; firstly that we are programmed to die at the cellular level and secondly cells die as a result to accumulation of toxic materials, waste and mutations and hence undergo senescence (a processes of deterioration).
Telomerase is an enzyme which elongates telomeres and mutations in these enzymes can lead to premature ageing. Many anti-ageing therapies have this enzyme in it. Cosmetic industries are spending millions to develop the use telomerase activating agents in anti-ageing products. Cancer cells become immortal due to increased activation of telomerase.
1. The number of times the body or somatic cells can replicate/divide are fixed. The protective telomeres present at the end of chromosomes get shorter. Chromosomes are packed form of DNA in a cell. Telomeres are the ends of chromosomes that maintain the viability of cells and when it’s lost; cells undergo apoptosis or perish. As cells divide telomeres become shorter and it can no longer protect the chromosomes. Cells also loose their ability to divide. This lack of maintenance of DNA leads to genetic instability. This leads to deterioration of organs in the body that can lead to ageing.
2. The accumulation of damage due to exposure to “reactive oxygen species” or “free radicals” during our lifetime either by intracellular source or external sources (e.g. UV) causes damage to the mitochondria (power house-generation and energy metabolism). This causes cell necrosis and loss of cell viability.
3. Its well known that smoking can cause the ageing of the skin and damage to the connective tissue (bones, cartilage) leading to accelerated ageing.
4. Buildup of mutations that cannot be suppressed is deleterious to the cell leading to its death.
5. “Antagonistic pleiotropy theory” suggests that the natural process of selection (evolution) causes mutations that makes us fit for survival at early stages of live. This is on the expense that we might not be as fit later in life. Therefore ageing is a side-effect of survival (in the early stages of our lives).
6. Enhanced long life is a trait in families. Some genes that code for proteins protects from certain diseases (such as heart diseases and Alzheimer’s) increases lifespan are inheritable.
7. In some species reproducing is related to longevity. For example, Atlantic salmon dies as soon as its reproduces.
8. Cells on its last legs are a preprogrammed cellular phenomenon for preventing cancer. Cells die as a method to prevent tumour formation (precautionary).
9. Accumulation of damaged proteins, free radicals and waste products in cells leads to ageing.
The science of ageing: We die at the cellular level. We pass away because our cells do. Cells expire because protective telomeres are lost and it can't protect the DNA. As cells die in organs (heart, digestive system, eyes etc) it begins to deteriorate and becomes less effective. We ultimately breathe our last.
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