By deciphering the molecular signatures of millions of mouse cells, Junyue Cao has found that aging is not haphazard wear and tear but rather a “remodeling of the cell society.”

Junyue Cao, a cell biologist at Rockefeller University in New York City, analyzed gene expression in millions of mouse cells from different life stages. He was surprised to find that “changes in aging are not universal across all the cells,” he said.

Karen Dias for Quanta Magazine

Introduction

In some ways, we know aging when we see it, from the graying of hair to the wrinkling of skin to declines in motor, sensory, and cognitive capacities. Yet the underlying biology of aging remains a matter of uncertainty and debate. Many lines of research align with the theory that aging is a direct result of decay — the inevitable degradation of molecules (including proteins or DNA), organelles, cells, or whole organs — from external assault or inexorable breakdown. When the body’s repair mechanisms fail to keep pace with these changes, like a factory with deteriorating equipment and too few mechanics, it manifests as the known signs of aging and, eventually, death.