The astonishing machine you have been living in all along

Bill Bryson has spent a career making complicated things comprehensible and, somehow, funny. The Body: A Guide for Occupants, published in 2019, applies this talent to the structure and function of the human form — a subject that turns out to be inexhaustible in its strangeness. It is not a medical textbook and does not try to be; it is a tour, guided by someone who has clearly been astonished by what he found.

Bryson moves through the body system by system — skin, brain, blood, skeleton, heart, lungs, gut, immune system — pausing in each to describe both how things work and how we came to understand that they work that way. The history of medicine embedded in the book is as interesting as the biology: a long, often gruesome story of wrong turns, lucky accidents and extraordinary courage among the physicians who volunteered themselves as experimental subjects.

Some of the book's most striking passages concern scale. The body manufactures vast numbers of cells continuously; the heart performs its work without pause across an entire lifetime; the gut contains a microbial ecosystem of staggering complexity. Bryson resists the temptation to make these facts merely impressive — he uses them to argue that the body is doing something genuinely remarkable, most of the time unnoticed.

The book ends with old age and death, handled with the same mixture of curiosity and good humour that characterises the rest of it. Bryson does not pretend to have a prescription for health — the book is not that kind of guide. What it offers instead is the pleasure of understanding, a little better, what you actually are.