Your body is constantly building itself. Right now, while you’re sitting still, your cells are dividing, replicating, and replacing each other at a furious pace. Scientists estimate the average human body produces around 4 million brand-new cells every single second - which adds up to about 330 billion a day.
Different parts of you renew at different speeds. The lining of your stomach replaces itself every 4 to 5 days (it has to - stomach acid is fierce). Your skin sheds its outer layer every 4 weeks. Red blood cells last about 4 months. Bone cells take around 10 years. Only a few cells, like neurons in your brain and lenses in your eyes, basically stay with you for life.
That means a lot of the “you” of a few years ago is gone - replaced, atom by atom, cell by cell. The you of today is partly a freshly-built copy. Same plan, brand-new parts.
