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Atomic Tune-Up: How the Body Rejuvenates Itself

On <em>Star Trek,</em> Dr. Leonard McCoy, played by actor DeForest Kelley, never wanted to be beamed anywhere because he worried it would scatter his atoms across the universe.
Hulton Archive/Getty Images
On Star Trek, Dr. Leonard McCoy, played by actor DeForest Kelley, never wanted to be beamed anywhere because he worried it would scatter his atoms across the universe.

For most people, a makeover means losing weight and getting new clothes, hair and makeup.

But what they may not know is that the body does its own extreme makeover regularly. In fact, 98 percent of the atoms in the body are replaced yearly.

Researchers in the 1950s made the discovery by feeding their subjects radioactive atoms. Using radiation detectors, the researchers watched the atoms move all over the body. They found that the new atoms replaced old ones and ended up in all tissues of the human body.

But these atomic makeovers prompt a more philosophical question: Are people really themselves if their atoms are always new, or are they new people each year? David Kestenbaum tackled that philosophical question — and discussed atomic makeovers — with the experts.

Copyright 2023 NPR. To see more, visit https://www.npr.org.

David Kestenbaum is a correspondent for NPR, covering science, energy issues and, most recently, the global economy for NPR's multimedia project Planet Money. David has been a science correspondent for NPR since 1999. He came to journalism the usual way — by getting a Ph.D. in physics first.