Why Do You Age?

Gerontology, the study of aging, is a relatively new science that has made incredible progress over the last 30 years. In the past, scientists looked for a single theory that explained aging, but have realized that aging is a complex interaction of genetics, chemistry, physiology, and behavior. There are now dozens of theories of aging to explain this inevitable fact of being human.

Young and old hands, side by side
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Programmed Theories of Aging

Programmed theories assert that the human body is designed to age and there is a certain biological timeline that bodies follow. All of these theories share the idea that aging is natural and "programmed" into the body.

There are a few different programmed theories of aging:

    • Programmed longevity theory is the idea that aging is caused by certain genes switching on and off over time.
    • Endocrine theory is the idea that regular changes in hormones control aging.
    • Immunological theory states that the immune system is programmed to decline over time, leaving people more susceptible to diseases.

Error Theories of Aging

Error theories assert that aging is caused by environmental damage to the body's systems, which accumulates over time.​

There are several error theories of aging:

    • Wear and tear theory asserts that cells and tissues simply wear out.
    • Rate of living theory is the idea that the faster an organism uses oxygen, the shorter it lives.
    • Cross-linking theory states that cross-linked proteins accumulate and slow down the body's processes.
    • Free radicals theory asserts that free radicals in the environment cause damage to cells, which eventually impairs their function.
    • Somatic DNA damage theory is the idea that genetic mutations cause cells to malfunction.

Genetic Theory of Aging

Studies have demonstrated that genetics can play a major role in aging. In one study, when researchers removed cells containing certain genes from the organs of mice, they were able to extend the lifespan of the animals by as much as 35%. The meaning of these experiments for humans is not known, but researchers think that genetics account for much of the variation in aging among people.

Some key concepts in genetics and aging include:

  • Longevity genes are specific genes that help a person live longer.
  • Cell senescence is the process by which cells deteriorate over time.
  • Telomeres are structures on the end of DNA that eventually are depleted, resulting in cells ceasing to replicate.
  • Stem cells are cells that can become any type of cell in the body and hold promise to repair damage caused by aging.

Biochemical Theory of Aging

No matter what genes you have inherited, your body is continually undergoing complex biochemical reactions. Some of these reactions cause damage and, ultimately, aging in the body. Studying these complex reactions is helping researchers understand how the body changes as it ages.

Important concepts in the biochemistry of aging include:

  • Free radicals are unstable oxygen molecules that can damage cells.
  • Protein cross-linking means that excess sugars in the bloodstream can cause protein molecules to literally stick together.
  • DNA repair is the concept that, for unknown reasons, the systems in the body that repair DNA seem to become less effective in older people.
  • Heat shock proteins are proteins that help cells survive stress and are present in fewer numbers in older people.
  • Hormones change as we age, causing many shifts in organ systems and other functions.

Anti-Aging Behaviors

The good news is that many of the causes of aging that may be happening prematurely can be modified through your behaviors.

Here are a few ways to keep your body feeling as young as possible:

  • Eat foods loaded with antioxidants to minimize damage caused by free radicals.
  • Exercise regularly to limit bone and muscle loss.
  • Keep your cholesterol low so you can slow the hardening of your arteries and protect your heart.
  • Practice mental fitness to keep your brain sharp.

In the end, aging is inevitable. Take care of your body and mind and embrace the changes as they come.

6 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
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