The telomere theory suggests that telomeres, which are protective caps at the ends of chromosomes, play a crucial role in cellular aging. Each time a cell divides, its telomeres shorten, eventually leading to cell senescence or death when they become too short. This process is believed to contribute to the aging of tissues and the overall organism. Research indicates that the length of telomeres can be influenced by various factors, including genetics, lifestyle, and environmental stressors. Telomerase, an enzyme that can extend telomeres, is active in certain cells, such as stem cells and cancer cells, allowing them to divide indefinitely.