5 astonishing facts about your own body from Bill Bryson’s new book

Bill Bryson first shambled onto our shores from his native US in 1973, an instinctive anglophile. Since then he has turned a kindly and satirical eye on everything from the rationing of hot baths in coastal B&Bs (Notes from a Small Island, 1995) to the elusive genius of Shakespeare (2007) and the fiery birth of the planet Earth (A Short History of Nearly Everything, 2003).

Having graduated from genial travel writing to popular science, Bill Bryson wields a childlike determination to keep asking questions until he understands something well enough to explain it. How do you weigh the Earth? How does a human blood cell work? Why can’t we live forever?

Curiosity is the driving force of science – and in Bryson’s case that also rings true of science writing. At a time when you can’t throw a crystal without it hitting an anti-vaxxer, an antioxidant moisturiser or a marginally qualified wellness guru, his latest book is particularly welcome. In The Body: A Guide for Occupants​, Bryson brings all his usual powers of poetry and precision to “the warm wobble of flesh” that is our enigmatic home.

As usual, the book is filled with enough factoids to fuel many a late-night conversation in the pub, but here are a few of my favourites.

1. You cost £96,546.79 to build. Or at least a human of the same dimensions as Benedict Cumberbatch does, according to a Royal Society of Chemistry calculation that Bryson cites. As The Body makes vividly clear, we are both mundane and miraculous: composed of a bunch of mostly everyday elements, pieced together in astonishingly complex systems that scientists today are still a long way from understanding.

To run the numbers: you are 61 per cent oxygen (£8.90) and 10 per cent hydrogen (£16), mostly bound up together to make water. It gets pricier when we get to carbon, which costs £44,300 for the 30lbs’ worth we typically contain. Calcium, phosphorus, potassium and a smattering of rarer elements make up the rest. But as Bryson writes: “It hardly matters. You could call together all the brainiest people who are alive now or have ever lived and endow them with the complete sum of human knowledge, and they could not between them make a single living cell, never mind a replicant Benedict Cumberbatch.”

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2. You get cancer every day. Or you would do if your natural defences weren’t cellular stormtroopers. “Every day, it has been estimated, between one and five of your cells turns cancerous and your immune system captures and kills them.”

And there isn’t just one “immune system”. Every individual’s immune system is both unique and changeable: it varies if you are stressed or exhausted. Little wonder, then, that our understanding of so many illnesses remains murky. While techniques that harness the body’s immune response are proving successful against some types of cancer, in other areas we remain woefully stumped. Auto-immune diseases – a category including allergies in which your own immune system works against you – remain poorly understood and largely incurable. As Bryson writes, it’s a “grossly sexist” type of illness: 80 per cent of sufferers are women.

3. Race is one millimetre deep. Intrepidly attending the dissection of a corpse, Bryson quotes the surgeon who pulled back a minute layer of skin and said: “That’s all that race is – a sliver of epidermis.” As we spread across the world, some people are thought to have evolved lighter skin in order to glean vitamin D from weaker sunlight. Throughout human history, people have “de-pigmented” and “re-pigmented” to suit their environment.

Biologically, skin colour is just “a reaction to sunlight”, Bryson quotes the anthropologist Nina Jablonski as saying. She adds: “And yet look how many people have been enslaved or hated or lynched or deprived of fundamental rights through history because of the colour of their skin.”

4. You just aren’t built to walk on two legs. When our ape-like ancestors came down from the trees, there was an evolutionary advantage to walking upright: we could cover more ground and see further. But our skeleton is still largely engineered to cope with life on four feet, not two. As Bryson writes: “Becoming upright put extra pressure on the cartilage discs that support and cushion the spine, in consequence of which they sometimes become displaced or herniated in what is popularly known as a slipped disc.” General back pain is ridiculously common: some 60 per cent of adults suffer from it. Our knee and hip joints are nothing to brag about, either, giving out with dispiriting frequency.

But where we have really paid the price – as anyone who has been anywhere near a labour ward can testify – is in our ability to give birth. At a time when the cult of natural childbirth makes women feel as though they are perfectly formed to expel a baby with only a scented candle and a visualisation exercise or two for comfort, this is vital stuff. Bryson writes:

“Above all, the adoption of a narrower pelvis to accommodate our new gait brought a huge amount of pain and danger to women in childbirth. Until recent times, no other animal on Earth was more likely to die in childbirth than a human, and perhaps none even now suffers as much.”

5. You shed half a kilo of skin flakes every year. Enough said. Read The Body, just don’t read it over a bowl of pasta with shavings of parmesan.

The Body: A Guide for Occupants is out now