The concept and realization of aging has been around since the olden days. Nearly all cultures and religion recognize the stages of life and divide it into phases, depending on the age and position in society. In Hinduism, there is the concept of Ashrama – which defines the four stages a person would find themselves during their lifetime. These four stages are Brahmacharya (in which a person is a student), Grihastha (wherein a person is a householder), Vanaspratha (in which one is retired) and Sannyasa (where the person gives up all the luxuries of life).
Owing to these defines stages of life, we know that whatever starts must end. As life progresses, things tend to slip out of our hands and a stage is reached where nothing can be called ours. Despite of all of this, life moves on. It takes the role of other things in the biological system – what comes from the soil goes back to the soil.
This wear and tear of a living organism is the essence of life; it happens to the smallest of the leaves and the greatest of the organisms to live on the earth. Still, as one life ends, another begins – thus maintaining the cycle of life. This can be attributed to reproduction – which, from a scientific standpoint, is the purpose – as the old generation passes away and the newer generation takes over the reins.
One well aware of regeneration and death of cells (called APOPTOSIS) knows that the death of a cell isn’t the end of an organism, referring to the fact that cells die every day, being replaced by young cells which continue the same functions in our body. It is a near-perfect process of repair and regeneration – then why do we age? Why does our body, at some point in our life, decide that the cellular processes and repair mechanisms should slow down?
There have been hundreds of scientists, putting forwards thousands of theories to explain the ‘whys’ of aging – only to conclude that aging is a complex combination of GENETIC AND ENVIRONMENT FACTORS acting on our cells.
Which environmental factors determine our life expectancy?
Environmental traits are all acquired – which means they are experienced throughout life and not predisposed since the birth of a person. Factors such as nutrition and lifestyle greatly affect the reaction of our body to them, thereby influencing the aging of cells.
It is logical to think a person with a balanced diet will have a higher life expectancy than one who is malnourished. The biologically-important molecules acquired from the food are of essence for the proper functioning of the body. A malnourished person will be more susceptible to the inability of cells to repair themselves and thereby, cause faster aging. A healthy person will have enough energy and biomolecules in their cells to sustain their body for a longer time and show decreased signs of aging.
Similarly, the lifestyle of an individual is an indispensable characteristic factoring into the aging of cells. Those working in poor conditions such as industries with high emissions will be prone to diseases – such as of the respiratory tract, which is observed in the case of workers in a chemical factory. Due to continuous exposure to harmful gases produced from the chemical industry, the body of a worker will expectedly retard at a greater rate, giving rise to diseases, therefore decreasing their life expectancy.
Along the same lines, a person exposed to CARCINOGENS (agents that can induce cancer) or MUTAGENS (agents that can induce mutations), such as ultraviolet light (UV light), tobacco or drugs is predisposed to undergo faster aging since the cell repair systems cannot keep up with the damage caused due to being exposed to these agents. The indirect way is these agents causing diseases (such as oral cancer, as observed in people engaged in consuming tobacco) and therefore, accelerating aging.
Keep in mind that these factors are taken into consideration concerning NATURAL DEATH, as opposed to accidental death.
What are the genetic factors influencing aging?
Our genetic material, DNA, has a SEMI-CONSERVATIVE REPLICATION, which is a rather complex mechanism by which a DNA strand divides into two and continues replication. This also plays a crucial role in CELL DIVISION – since each daughter cell required the same amount of DNA present in the other cells.
It is important to note that DNA replication is not perfect. In all cases of replication of DNA, a part of the strand (containing GENES) is not replicated. Since each cell needs to have the same amount of DNA as in the other cells, a ‘useless’ piece of DNA called the TELOMER is added to the ends of the DNA strands. This ensures that the replication continues without any error in the length of the genetic material.
The replication process is not perfect also since the length of the telomeres keeps on increasing with subsequent cell divisions – thus ‘aging’ the cells. The increasing telomeric length puts an expiration date on the cells – that is, it can replicate on an average of 50 times before permanently dying. This is the cause of ‘aging’ as we know it.
This has been labeled the most logical and widely-accepted theory of aging – but scientists all over the world have been working to pinpoint the exact reason for a person growing old. Some scientific communities back an evolutionary aspect to aging – saying that humans are programmed to die after fulfilling the biological purpose of life, which is reproduction. According to this theory, the genes which help in the development of an adult body prove to be detrimental to the individual in the later stage of life. A loophole in this theory is the unknown trigger which causes the genes to switch from beneficial to detrimental.
Another theory that is not well-defined but makes sense is that of the presence of FREE RADICALS. Free radicals are chemical entities that carry a singular charge and prove to be the by-products of metabolic processes such as respiration and digestion of food. Free radicals, when allowed to accumulate in the cells, can disturb the regular functioning of cells, leading to cells not being able to repair themselves effectively.
Nonetheless, as the standards of life have risen, there has been a drastic increase in life rates. This is a clear indication that environmental factors greatly influence the rate of aging. So it would seem like the secret of a long life is maintaining a healthy body – mentally, physically and socially.