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How is biological aging different from chronological age?

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primates — aging Primates are among the longest-lived groups of mammals.

It is important to distinguish between chronological age and biological aging, as they measure different aspects of an individual's life span.

Chronological age is a simple measurement of time, defined as the age of a person calculated from their birth to a specific date. It is a linear progression that does not account for the physical state of the body.1

Biological aging, in contrast, refers to the progressive physiological changes that occur within an organism over time. This process, often studied under gerontology, involves a decline in biological functions and a reduced ability to adapt to metabolic stress. Unlike chronological age, biological aging is influenced by a complex interplay of factors, including:23

Genetics: Programs within our genes and the shortening of telomeres during cell division play a fundamental role in determining lifespan.4
Cellular Damage: The accumulation of oxidative damage from reactive oxygen species and other metabolic byproducts can impair cellular function.45
Environmental Factors: Lifestyle choices, such as diet and exercise, as well as exposure to toxins, can accelerate or mitigate the rate of physiological decline.4

While chronological age tracks the passage of years, biological aging tracks the actual functional decline of cells, organs, and the total organism.23