Why don't organisms just live forever?

Organisms don't live forever due to a combination of genetic, environmental, and evolutionary factors. Aging, or senescence, is a result of the accumulation of cellular damage over time and the gradual decline in biological functions. Additionally, evolution favors traits that enhance reproductive success rather than longevity, leading to the natural selection of organisms that can thrive and reproduce within a limited lifespan. Ultimately, the energy and resources required for maintenance and repair become unsustainable, leading to the eventual end of life.