It’s all around us.
The news media keeps an ongoing record of accidents and mayhem that end in death. It’s dramatic. Traumatic. Especially when the mayhem is high. But the death inside our bodies is even more dramatic—just less reported.
The Fable of the Seven-Year Self
There’s a common claim that every seven years we become a new person— that every cell in our body dies and is replaced. Sometimes the number is ten years instead. Either way, it’s a fable. There’s no evidence. What is true? Death is happening constantly—every second—inside us. And quietly.
Life Spans Within
Take red blood cells: They live about four months. Not all at once—thankfully. At any moment, some are newborn, some middle-aged, some old. White blood cells live around a year. Skin cells last about two to three weeks. And when we age, the replacements lose precision— each copy a little more worn. Colon cells? They live about four days. They die fast, and we hope their replacements know what they’re doing.
We Are Renewal
There are somewhere between 50 and 75 trillion cells in the human body. Each with its own clock. Each in its own phase of death and replacement. So while the idea of being “entirely new” every seven years isn’t true, the truth is actually better: We are in a constant state of renewal. Every day. Every hour. Every second.
The Brain Stands Still
Except—there’s one place where this renewal mostly stops: The brain. Neurons are largely fixed from birth. We don’t grow new ones. We just try to preserve the ones we’ve got. Certain activities can kill them off—but new ones don’t take their place. So, in that sense: You are the same throughout your life. Your thoughts live in cells that do not regenerate.
The Final Timeline
Here’s one last fact to consider: Our cells don’t die when our bodies do. At first, they carry on as if nothing has happened. The system runs on residuals. But soon: the lights go out, the trash stops being picked up, the furnace grows cold. Eventually, every cell gets the message. That’s when the clocks sync. That’s when the body as a whole finally ends. So no—we are not reborn every seven years. But we are always in motion, always turning over.
Always a work progressing.
