The cartilage in your joints is smoother than glass, and has a friction coefficient five times less than ice. The more exercise we do the more our bones produce a hormone that boosts mood, fertility and memory – staving off frailty, depression and dementia. Taste receptors trigger insulin release, so that before we’ve even swallowed our bodies are preparing for a meal (there are even taste receptors in the testicles). We are made of seven billion billion billion atoms, the constituent elements of which would cost £96,546.79 on the open market (excluding VAT). A study of 60 people’s belly buttons found 2,368 species of bacteria, 1,458 of them “unknown to science”. Our ears can discern a volume range of a 1,000,000,000,000 factors of amplitude. Over a lifetime your heart performs the equivalent work to lifting a tonne weight 150 miles into the air. Through her nipples a breast-feeding mother’s body gauges the microbes in her baby’s saliva, to adjust the antibody content of her milk. If you laid all the DNA in your body end to end it would stretch 10bn miles, beyond the orbit of Pluto: “Think of it: there is enough of you to leave the solar system,” Bill Bryson writes; “You are in the most literal sense cosmic.”

Bryson’s The Body is a directory of such wonders, a tour of the minuscule; it aims to do for the human body what his A Short History of Nearly Everything did for science. He has waded through a PhD’s worth of articles, interviewed a score of physicians and biologists, read a library of books, and had a great deal of fun along the way. There’s a formula at work – the prose motors gleefully along, a finely tuned engine running on jokes, factoids and biographical interludes.

Bryson is concerned not just with the peculiarities of our bodies, but their expiry dates

His introduction, “How to Build a Human”, explores the mystery of life, why £96k worth of atomic matter self-organises into the miraculous and autonomous beings that we are (spoiler alert: no one really knows). After dispensing with the skin and hair (“no one ever died of baldness”), and the trillions of bacteria that share our bodies (“bacteria can swap genes between themselves, like Pokémon cards”), the brain, head, throat, heart, liver, skeleton, lungs, guts and genitals are given the Bryson treatment: wry, companionable, avuncular and always lucid. Despite his geniality, the pace is breakneck: six pages of the 454 span the history of cardiac surgery (a subject Thomas Morris’s The Matter of the Heart recently spent more than 400 pages on). In an express chapter on pain and nerves, migraine is allotted just one paragraph, as is the pain of cancer.

Wry, companionable, avuncular and always lucid … Bill Bryson. Photograph: Dan Himbrechts/EPA

Bryson’s tour of the marvellous arcs into the remarkable achievements of an elite few of our fellow humans: the toddler who was fully resuscitated from hypothermia even though her heart had stopped for hours; the flight attendant who survived a fall of 33,000ft, cushioned by fir trees; the Spanish diver who held his breath for 24 minutes; the Chilean miners who do hard labour 19,000ft up a mountain. In terms of our reproductive capacities, you might be interested to know that the chance of conceiving on a single, randomly timed act of sex is 3%, the lucky sperm welcomed to the egg “like a long-lost if curiously diminutive friend”. As for the average size of the human penis, you can find it on page 287.

Bryson is concerned not just with the peculiarities of our bodies, but their expiry dates: through the 20th century, human life expectancy improved as much again as in the previous 8,000 years. The first thousand days of life from conception are crucial for your future health – stress in early childhood, and in the womb, makes you an unhealthier and more miserable adult. Junk food and sedentary lives mean that children born now are expected to have shorter lives than their parents – a development that prompts Bryson into a rare bitter jibe: “We aren’t just eating ourselves into early graves, it seems, but breeding children to jump in alongside us.” This is a political more than a medical problem, and it has political solutions: men in the East End of Glasgow have a life expectancy of 54, 25 less than the UK average – improving that statistic requires government action, not medicine. A 30-year-old black man in Harlem has a worse prospective lifespan than a 30-year-old Bangladeshi, just on the basis of stroke, diabetes and heart disease risk, and excluding drug deaths and violence. What factors improve our life expectancy? “One is that it is really helpful to be rich,” Bryson answers. And the second? “That it is not a good idea to be American.”

In the final chapters he gets angrier, and the book becomes even more interesting. He points out that even rich Americans die younger than the average-income European because of diet, obesity and America’s anomalous, hyper-expensive and iniquitous healthcare system. Bryson was born in Iowa but has made his home in Britain, and relates with barely disguised horror that the average American eats two entire cheesecakes-worth of calories more than the average person in Holland or Sweden, every week. Americans shoot one another more often than anyone else, drink and drive more than “almost anybody else” and wear seatbelts less frequently than anyone but the Italians. Insulin, the patent for which was donated by its discoverers for the good of mankind, is six times more expensive in the US than in Europe. Cuba and Lithuania have better infant survival rates than America. The US has double the number of financial administrators in its healthcare system than it does physicians. And just in case Brits are starting to feel smug, Bryson points out that UK government austerity between 2010 and 2017 has led to about 120,000 preventable early deaths. To its shame, the UK languishes among the poorest in the developed world in terms of cancer survival – because the very barriers to specialist care that make the NHS comparatively cheap to run also make it lumberingly slow.

The more exercise we do the more our bones produce a hormone that boosts mood, fertility and memory. Photograph: Colin Anderson/Getty Images/Blend Images

On the subject of prostate cancer, the PSA test is “hardly more effective than a coin toss” according to Professor Richard J Ablin, who discovered it in 1970: “I never dreamed that my discovery four decades ago would lead to such a profit-driven disaster” (one of many moments in The Body when I stopped to applaud, and scrawled in my notes “I wish all my patients would read this”). It makes sense that enjoying good friendships in later life might promote longevity, but Bryson notes that a positive social and emotional life seems to actually protect our DNA. In one study looking at diabetic care and outcomes, the patients of doctors who were rated highly for compassion had a 40% lower complication rate.

You are a walking, talking catalogue of wonders. “And how do we celebrate the glory of our existence?” Bryson asks. “Well, for most of us by exercising minimally and eating maximally.” For all Bryson’s encyclopedic reading, his brain-picking sessions with medicine’s finest minds, the ultimate conclusions of his book could stand as an ultimate prescription for life: eat a little bit less, move a little bit more.

• Gavin Francis’s Shapeshifters – On Medicine & Human Change is published by Profile/Wellcome. The Body: A Guide for Occupants is published by Doubleday (£25). To order a copy go to guardianbookshop.com or call 0330 333 6846. Free UK p&p over £15, online orders only. Phone orders min p&p of £1.99.