Why Do We Age: 5 Promising Theories

Everyone must have wondered at some point in their life,” Why do we age?”. Well if you want to know what aging is and how it occurs, this article might be of your interest.

Before looking into the question of why do we age? Let’s find out what aging is first.


Aging or Ageing as some might prefer is a series of gradual changes that occur in an organism that leads to a reduction in the organism’s biological functions1 and ability to adapt to metabolic stress.

The process of aging is not something that happens in days; it is a continuous process. Aging starts when we are born and ends when we die.

Loosening of skin, forming of wrinkles, and growth of gray hair are some signs that depict the aging process. Symptoms of age-related diseases like cardiovascular diseases2, diabetes, Parkinson’s disease, and many others also start showing. These symptoms make us wonder why do we age.

why do we age
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Why do we age is a question everyone is looking for an answer to. The processes that contribute to the aging process are a hot topic among academics. However, it is commonly known that the functional decline associated with old age is caused by damage to genetic information, tissues, and cells, that are collected with age and cannot be restored by the body. But it is less apparent what causes this molecular damage and why it can be healed in young creatures but not in elderly ones.

There are different types of aging as well. The various types of aging3 are mentioned below:

  • Cellular Aging

The basic building components of the body are cells. The cells are set up to divide, replicate, and carry out essential biological duties. A cell may replicate around fifty times until the genetic material can no longer be correctly duplicated.

The more cells that divide, the older they get. Cells gradually lose their capacity to operate correctly as a result of this. The more free radicals and environmental factors harm cells, the more cells are required to duplicate, and aging occurs more quickly.

  • Hormonal Aging

Hormones are known as chemical messengers of our body secreted directly into our blood vessels. They travel to different organs and tissues through the bloodstream.

Hormones have an important role in aging, and they aid in the development of secondary female or male features by helping to form bones and muscles.

why do we age
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Many hormones’ output decreases with time, which results in changes to the skin, like wrinkles and loosening of the skin, as well as a loss of bone density, muscle tone, and sexual desire.

Because males and females have different quantities and types of sex hormones, how they age varies as well.

  • Aging due to Accumulative Damage

Aging due to accumulative damage, also known as ‘wear and tear’ is the result of external forces that accumulate over time. It relates to how our environment and way of life influence how we age.

The external factors which affect the aging process are:

  • UV radiation
  • Pollution
  • Toxins
  • Poor meal
  • Alcohol Consumption
  • Drugs
  • Smoking

These environmental influences can cause DNA damage in cells over time. The accumulating damage might impair the body’s capacity to heal itself, hastening the aging process.

  • Metabolic Aging

Cells in our body are continually converting food into energy, producing byproducts, some of which are potentially hazardous to our health. While metabolization is necessary, it causes the human body cells to age prematurely. This is referred to as metabolic aging.

It is believed that metabolic aging can be slowed down by caloric restriction.

Aging Theories

Every living thing becomes old. But why do we age? Is there such a thing as biological sense? Experts are still split on how to properly answer these concerns. Several valuable insights and discoveries suggest that aging is influenced by both internal, and genetic factors and environmental causes.

why do we age
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Many theories on why do we age are available; the widely accepted one to get the answer to question of why do we age is known as Modern Biological theory.

Modern biological theories are divided into two sub-parts: ‘Programmed Theory’ and ‘Damaged or error Theory’.

1. Programmed Theories

According to programmed aging theories, people are meant to age, and the cells have a fixed lifespan that is imprinted into our bodies.

The theories under programmed theories suggest that aging is a natural process that is ‘coded’ into the human body.

The programmed theories include the following:

Gene Theory or Programmed Longevity Theory

Gene theory suggests that aging is described as the moment when age-related deficiencies are evident, and aging is the outcome of a constant turning on and off of certain genes.

The programmed theory includes the following notions:

Endocrine Theory

Endocrine theory suggests that aging is caused due the regulation of hormones. Hormones are produced by the endocrine system of our body, and changes in them can result in aging.

Immunological Theory

The immunological theory depends on the immune system. The immune system of our body is designed to deteriorate with time, increasing vulnerability to infectious illness and, as a result, aging and, then, finally death.

The immune system’s efficacy peaks at puberty and then steadily diminishes with age.

why do we age
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Many people believe in programmed theories to answer the question of why do we age. They do, however, claim that practices associated with longevity, such as stopping smoking and exercising, are ineffective. This is most likely incorrect, as research has repeatedly shown that these behaviors have an impact on life expectancy.

2. Damaged or Error Theories

Damaged or error theories are a little different than programmed theories, they believe that aging is caused by unplanned and unpredictable cellular changes.

The different theories under damaged and error theories are as follows:

  • Wear and Tear Theory: Cells degrade and become destroyed over time, according to this theory.
  • Cross-Linkage Theory: According to this theory, cross-linked proteins build up the body’s functions and are slowed down. The accumulation of cross-linked proteins causes aging, which destroys cells and hinders biological functioning.
  • Free Radical Theory: According to this idea, aging is caused by the accumulation of oxidative stress generated by free radicals.
  • Somatic DNA damage Theory: DNA damage occurs in living creatures’ cells on a regular basis. The assumption that genetic mutations are the origin of cells to fail is based on the fact that most of these damages are corrected, but some accumulate because DNA polymerases and other repair systems cannot remove faults as quickly as they are seemingly created.
why do we age
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  • Rate of Living Theory: According to proponents of this idea, an organism’s metabolic rate affects its longevity. It is the notion that the quicker an organism consumes oxygen, the shorter its life span.

Along with the Modern Biological theories, there are other types of aging theories as well:

3. Evolutionary Theory of Aging

Aging is said to be the result of natural selection, according to evolutionary theories. According to this theory, an organism begins to age after reaching the prime of reproduction and passing on adaptive features.

Natural selection of an organism refers to an organism’s adaptive features. These characteristics can aid an organism’s ability to adapt to its surroundings, increasing its chances of survival.

Evolutionary theories mention the following:

  • Mutation accumulation: Random mutations are bound to accumulate later in life, according to this theory.
  • Antagonistic Pleiotropy: Genes that increase fertility early in life, according to this notion, have detrimental consequences later in life.
  • Disposable Soma theory: According to this theory, as more metabolic materials are devoted to reproduction, less is devoted to DNA repair. Cell damage and aging are the end results.

The evolution theories are yet not proved completely; research on the same is being done to collect more pieces of evidence.

4. Genetic Theory of Aging

The genetic theories of aging are somewhat based on similar concepts of programmed theories.

According to this theory, genetics is the most important factor in aging. In other words, the genes we inherited from our parents determine how long we live and how quickly we age.

why do we age
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Genetic theories disregard the fact that environmental factors affect the life span.

Genetic theories include the following:

  • Telomere Theory: Telomere is the structures present at the end of DNA that decrease with time, causing cells to stop reproducing. Telomere4 shortens with age and is linked to illness.
  • Programmed Senescence Theory:  When cells cease dividing and developing but do not die, this is known as cellular senescence. This idea claims that this is the cause of aging.
  • Stem Cell Theory:  Stem cells have the ability to transform into different cells, which aids in tissue and organ repair. Stem cells are cells that have the ability to transform into any kind of cell in the body. However, stem cell activity reduces with age, perhaps contributing to aging.
  • Longevity Gene Theory:  This is the belief that particular genes might help you live longer. Genes that can help a person live longer are known as longevity genes.

5. Biochemical Theory of Aging

Our body is always undertaking intricate molecular processes, regardless of the genes, we have inherited. Some of these responses can cause damage to the body and, as a result, aging.

why do we age
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According to the biochemical theory, aging is caused by biochemical processes. These reactions happen all the time in life and are quite natural.

Biochemical theories of aging include the following:

  • Advanced Glycation End Products:  When lipids or proteins are exposed to sugar, Advanced Glycation End Products form. High amounts can cause oxidative stress, which accelerates the aging process.
  • Protein Cross-Linking: Protein molecules can physically cling together if there are too many carbohydrates in the circulation, which results in aging.
  • DNA Repair: It is the idea that the body’s DNA-repair processes grow less effective as people become older.
  • Heat Shock Proteins:  Heat shock proteins are proteins that assist cells in surviving stress and are seen in lower amounts in the elderly, which can be the cause of aging.
  • Hormones: As we become older, our bodies evolve, producing significant changes in various parts of organs and other processes.

Life Expectancy Rate

Recent years have seen an increase in life expectancies around the world. The following factors could possibly be the reason for it:

  • Improved dietary habits
  • Better sanitation and hygiene
  • Modern medicine has improved access to healthcare
  • Modern technologies

Can Aging Slow Down?

Growing old is a scary concept, but it is inevitable. You might get the answer to why do we age, but you can do nothing to avoid the process of aging. Can the process of aging be slowed down? Yes, your characteristics and behavior have a direct impact on your speed of aging.

If you want to slow the effects of aging, the following habits should be included in your daily life:

  • Take a nutritious diet:  Eat a meal that consists of nutrition and other important minerals. Avoid regular eating of fast foods. Fruits and vegetables should be taken in plenty to stay healthy.
  • Limit Alcohol Consumption: It is a known fact that drinking alcohol is injurious to health. And if you do not stay healthy, there are chances that your body will fall prey to many diseases. This will speed up the aging process for you.
  • Avoid Tobacco Consumption: Just like alcohol, smoking and taking drugs acts as a catalyst in the process of aging. Avoid falling prey to these bad habits and if you have started taking part in these practices, try quitting slowly with the help of a professional.
  • Stay Active: Exercising helps you in keeping your body fit and healthy, which has a positive slowing down the process of aging. The exercise regime should not be something over the top, and it should just help you in staying active.
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  • Mental Exercises: Along with physical exercise that helps you in staying active, do mental exercises as well to keep your mind refreshed. This helps in increasing the cognitive functions of the brain.
  • Apply Sunscreen: UV radiations are harmful to our skin and speed up the process of aging. Apply sunscreen on your body when you are going to get exposed to UV radiation.
  • Get Checked Regularly: Even if you feel you are healthy and are having the best time of your life, having regular checkups is necessary. In this way, any underlying diseases whose symptoms are not noticeable can be detected early, and treatment could be provided.
  • Recognize your family’s history: Discuss your family’s medical past with your doctor to ensure that you receive the proper screening or treatment for any suspected chronic conditions.

Women Live Longer than Men

Yes, you read that right. Women tend to live longer than men, and there is a scientific reason behind it.

The presence of estrogen in women is the cause of delayed aging in women. Estrogen is the sex hormone found in females that aids in the development and maintenance of the reproductive system as well as feminine traits like breasts and pubic hair.

why do we age
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The estrogen found in females has been known to have anti-inflammatory and immune-boosting properties, which might protect women from certain ailments.

The male sex hormone is known as testosterone; it is most commonly linked to sexual desire and is essential for sperm production. It also has an impact on bone density and muscle mass, fat storage in men’s bodies, and red blood cell synthesis.

Testosterone, a male sex hormone, is known to inhibit the immune system. Although testosterone is present in women also, it is present in less quantity. This hormone is often seen in higher concentrations in men.

The behavioral factors between men and women also affect the longevity of aging between the genders. Behavioral differences like:

  • Women tend to drive safely or take general precautions in everything they do.
  • Women are known to drink less alcohol, less smoking, and the consumption rate of drugs among women is also small as compared to men.
  • If the need arises, it is found that women access healthcare services more as compared to men.

Why do we Age?

The question of why do we age? can not be answered in one word or in one phrase. There are a variety of factors that affects the aging process.5 The aging theories mentioned in this article also do not give the exact reasons why do we age.

Researchers all around the world are working on testing existing theories and providing the most suitable one. New theories on why do we age are also being released, but they also do not have the proper results and pieces of evidence to support them.

There is no cure for aging, and it probably never will be. Instead of fighting to age, we should attempt to identify the positive aspects of it since, in the end, even though our genome shapes play a role in aging, there is a lot we can do to stay healthy in our later years.

Instead of doing things to make your life span longer, try out things for healthy aging.

If you liked this article, here is something more.

  1. Lowenstam, Heinz A. “Minerals formed by organisms.” Science 211.4487 (1981): 1126-1131. ↩︎
  2. Gaziano, Thomas, et al. “Cardiovascular disease.” Disease Control Priorities in Developing Countries. 2nd edition (2006). ↩︎
  3. Obler, Loraine K., et al. “Aphasia type and aging.” Brain and language 6.3 (1978): 318-322. ↩︎
  4. Greider, Carol W. “Telomere length regulation.” Annual review of biochemistry 65.1 (1996): 337-365. ↩︎
  5. Fleming, Thomas H., et al. “Reactive metabolites and AGE/RAGE-mediated cellular dysfunction affect the aging process–a mini-review.” Gerontology 57.5 (2011): 435-443. ↩︎

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