DNA is the instruction manual for life—but it’s far from static. From the moment of conception to the last breath, mutations accumulate in every cell in the body. By the time it takes to read this sentence, says science writer Roxanne Khamsi, your DNA has already changed. A single white blood cell from a centenarian can carry more than 3,000 mutations amassed over a lifetime.
Drawing from her new book Beyond Inheritance, Khamsi argues that our bodies function as dynamic landscapes of genetic change where Darwinian evolution unfolds continuously. The effects can be devastating, such as when mutant blood cells outcompete their normal counterparts and increase the risk of heart attacks. But mutations can also make bodies more resilient: Liver cells with genetic changes seem to cope better with excess calories and immune cells remix their DNA to create more powerful antibodies that fend off disease.
Khamsi highlights the latest discoveries about how mutations shape health, immunity, and aging. She reveals how genetic changes in tissues can be both harmful and protective, challenges the idea that all cells carry identical DNA, and shows how this insight is reshaping medicine—including advanced vaccines and treatments that can outsmart cancer—while transforming the way we think about our bodies.
Khamsi’s book, Beyond Inheritance: Our Ever-Mutating Cells and a New Understanding of Health(Riverhead Books), is available for purchase.
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