Introduction :
Human aging has been a mystery since the dawn of civilization due to its biological complexity, involving genetic composition, inheritance, epigenetics, and a constantly changing living environment. Age is different from aging. Age is a measurable unit of time, such as years (chronological age), whereas aging is a multifaceted biological process.
Lifespan or lifecycle is defined as the duration from biological conception (gestation) to death. However, individual genetic inheritance, generational changes, and environmental influences across different age cohorts?along with their bio-psycho-social characteristics?make the understanding of aging more complex.
Aging is associated with continuous changes in molecular composition in human cells, with or without external environmental stimuli.
Extensive research has identified several hallmarks of aging, which include twelve major molecular changes: genomic instability, telomere attrition, epigenetic alterations, loss of proteostasis, impaired macroautophagy, deregulated nutrient sensing, mitochondrial dysfunction, cellular senescence, stem cell exhaustion, altered intercellular communication, chronic inflammation, and dysbiosis.1,2