What is Aging?

Normal cells in complex eukaryotes exhibit species-specific limits on their life span, characterized by gradual deterioration and loss of cellular function, ultimately leading to the individual's death. This predictable process of cellular decline is known as aging, a negative physiological change in the body.

Gerontology, the field of biology dedicated to studying aging, explores the various aspects of this phenomenon.

Aging is inherent in populations, with each species having a genetically determined range of life spans. While individuals within a species may vary in their expected life spans, there exists an approximate maximum life span for each species.

As organisms age, numerous functional and structural features demonstrate diminished or lost function. These changes, either independently or through interactive combinations, weaken an organism's ability to maintain homeostasis. Furthermore, age-related declines in specific immune resistance mechanisms increase susceptibility to infections.

Cellular aging is evident in tissues that lack significant cell turnover and replacement. For example, the nervous system experiences a progressive loss of cells throughout life. Various factors contribute to cell death during aging, such as the accumulation of aging pigments and the presence of DNA damage resulting from somatic mutations. These factors can disrupt cell function and limit cell division in tissues undergoing continuous replacement.

The extracellular components of tissues also undergo aging changes, particularly collagen fibers. These fibers, which form the permanent extracellular framework surrounding tissue cells, lose elasticity with age, leading to physical alterations such as wrinkled skin.

Abnormal aging can occur, characterized by dramatic changes associated with degenerative brain disorders or other diseases.

In conclusion, aging and death play crucial roles in creating space for new, young individuals within populations. From an evolutionary perspective, aging and death are necessary for the welfare and survival of our species. However, the desire for extended life spans remains highly appealing to individuals.