Why does the risk of death generally increase during human aging?

The risk of death increases during human aging primarily because of a gradual, progressive decline in biological functions and the body's ability to adapt to metabolic stress, a process known as senescence.12

As individuals age, they become increasingly vulnerable to disease due to several physiological changes:

• Organ Decline: The performance of vital organs, including the heart, kidneys, brain, and lungs, gradually diminishes over the life span.1
• Cellular Changes: There is a loss of cells within organs, and the remaining cells often function less efficiently, requiring more time for chemical reactions.1
• Accumulation of Damage: Theories such as the oxidative damage theory suggest that the accumulation of reactive oxygen species damages DNA and proteins over time, leading to cellular dysfunction.3
• Structural Changes: Tissues may become more rigid, and inert materials like lipofuscin or amyloid can accumulate, further impairing biological processes.4

Ultimately, these cumulative changes reduce the body's reserve capacities, making it harder to recover from stressors that a younger person might easily overcome.1