"Your body renews itself every seven years”: An idea that’s been around at least since John Dos Passos’s novel “Manhattan Transfer” (1925)

I'd have assumed that the idea that the cells in human bodies are completely replaced in a seven-year cycle arose during my lifetime, so I was surprised to find Congo in John Dos Passos's 1925 novel "Manhattan Transfer" making the point in a scene before World War One: "Your body renews itself every seven years." While I haven't been able to find out when the idea originated, or with whom, I have learned that while the average life of human cells may be seven to ten years, the life spans of cells vary widely, with some cells in the lens of the eye forming in the embryo and surviving until death. (Andrew Shields, #111Words, 30 March 2024)