Why Aging May Be a Program, Not a Breakdown

Aging, as we recognize it through physical changes like graying hair and wrinkled skin, as well as declines in physical and cognitive abilities, remains a topic shrouded in uncertainty and debate. The prevailing belief is that aging is the result of molecular decay and breakdown of various cellular and organ components due to external factors or inherent failure of repair mechanisms.

This perspective, however, is contested by cell biologist Junyue Cao, who argues that aging is a programmed process, not a random accumulation of wear and tear.

According to Cao, who directs the Laboratory of Single-Cell Genomics and Population Dynamics at Rockefeller University, aging is a stepwise and organized phenomenon that begins early in life. He utilizes advanced technology to study the aging process in mice, which reveals discrete stages akin to embryonic development, each characterized by specific molecular signals and cell population changes. Cao posits that the aging process likely initiates before the age of 30.

Cao's fascination with aging originated during his high school years in Hebei, China, when he witnessed the inevitable decline of his grandparents and parents. While many teenagers confronted mortality through poetry or self-destructive actions, Cao chose science, pursuing biology at Peking University. He initially believed that aging resulted from the degradation of specific proteins and their networks; however, his research revealed a far more intricate and organized system than anticipated.

Seeking comprehensive data, Cao developed a high-throughput technology capable of quantifying molecular changes across thousands of cells in various cell types. As a graduate student, he employed this technology to study aging from an embryonic development perspective. In his current laboratory at Rockefeller University, he applied this technique to aging studies, analyzing 21 million cells from 14 tissues or organs in 50 male and female mice at five life stages.

Cao's research, published in 2025 and 2026 in Science, demonstrates that aging involves a significant reorganization of cellular populations throughout the body. These findings suggest that aging is not merely a decline in specific cellular components but a systemic restructuring of the body's cellular composition. Cao's work also highlights the role of epigenomic instructions in guiding this process, emphasizing that molecular changes and cellular remodeling converge to drive the aging phenomenon.