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One of the most pleasant surprises I had this year was Bill Bryson's The Body: A Guide For Occupants.
I picked the book up on a whim, mostly because I've enjoyed Bryson's writing in the past. I wasn't particularly interested in learning more about the human body at the time, but as I've said elsewhere, allowing for serendipity to drive some of your learning is important. It allows for the unexpected connections that often (in my experience, anyway) prove to be the most profound.
I ended up tearing through the book in about a week. it's funny, engaging, and fascinating in turn. One of the most important take aways, for me, was that there is simply so much about the body we don't understand. What you might imagine to be basic questions - like "why do we get headaches?" and "what tells a baby it's time to be born?" - remain mysterious.
I found so many delightful facts in this book that it was bothering my wife. I'd keep turning over to her in bed and asking things like: "Did you know that almost three-quarters of the forty million antibiotic prescriptions written each year in the United States are for conditions that cannot be cured with antibiotics?"
At some point I was very politely asked to refrain from sharing surprising medical facts right before bed, so I've gathered some of my favorites here for you. All of these are quotes from the book.
I hope you enjoy them as much as I did, and please do check out the book - it's certainly worth a read.
On the likelihood of dying from something nasty
- The miracle of human life is not that we are endowed with some frailties but that we aren’t swamped with them.
- Most of the people who are prime candidates for heart attacks don’t get heart attacks. Every day, it has been estimated, between one and five of your cells turn cancerous, and your immune system captures and kills them. Think of that. A couple of dozen times a week, well over a thousand times a year, you get the most dreaded disease of our age, and each time your body saves you.
On the brain constructing your reality
- An interesting thing about touch is that the brain doesn’t just tell you how something feels, but how it ought to feel. That’s why the caress of a lover feels wonderful, but the same touch by a stranger would feel creepy or horrible. It’s also why it is so hard to tickle yourself. —
- For each visual input, it takes a tiny but perceptible amount of time—about two hundred milliseconds, one-fifth of a second—for the information to travel along the optic nerves and into the brain to be processed and interpreted. One-fifth of a second is not a trivial span of time when a rapid response is required—to step back from an oncoming car, say, or to avoid a blow to the head. To help us deal better with this fractional lag, the brain does a truly extraordinary thing: it continuously forecasts what the world will be like a fifth of a second from now, and that is what it gives us as the present. That means that we never see the world as it is at this very instant, but rather as it will be a fraction of a moment in the future. We spend our whole lives, in other words, living in a world that doesn’t quite exist yet.
- You don’t normally experience the blind spot, because your brain continually fills in the void for you. The process is called perceptual interpolation. The blind spot, it’s worth noting, is much more than just a spot; it’s a substantial portion of your central field of vision. That’s quite remarkable—that a significant part of everything you “see” is actually imagined.
- It is a strange, nonintuitive fact of existence that photons of light have no color, sound waves no sound, olfactory molecules no odors. As James Le Fanu has put it, “While we have the overwhelming impression that the greenness of the trees and the blueness of the sky are streaming through our eyes as through an open window, yet the particles of light impacting on the retina are colourless, just as the waves of sound impacting on the eardrum are silent and scent molecules have no smell. They are all invisible, weightless, subatomic particles of matter travelling through space.” All the richness of life is created inside your head.
On whose planet this really is
- If you put all Earth’s microbes in one heap and all the other animal life in another, the microbe heap would be twenty-five times greater than the animal one. Make no mistake. This is a planet of microbes. We are here at their pleasure. They don’t need us at all. We’d be dead in a day without them.
On preventing disease
- Study after study since then has shown that exercise produces extraordinary benefits. Going for regular walks reduces the risk of heart attack or stroke by 31 percent. An analysis of 655,000 people in 2012 found that being active for just eleven minutes a day after the age of forty yielded 1.8 years of added life expectancy. Being active for an hour or more a day improved life expectancy by 4.2 years.
- Levine found that lean people tend to spend two and a half hours more a day on their feet than fat people, not consciously exercising, but just moving about, and it was this that kept them from accumulating fat.
- Some people live longer than they ought to by any known measures. As Jo Marchant notes in her book Cure, Costa Ricans have only about one-fifth the personal wealth of Americans, and have poorer health care, but live longer. Moreover, people in one of the poorest regions of Costa Rica, the Nicoya Peninsula, live longest of all, even though they have much higher rates of obesity and hypertension. They also have longer telomeres. The theory is that they benefit from closer social bonds and family relationships. Curiously, it was found that if they live alone or don’t see a child at least once a week, the telomere length advantage vanishes. It is an extraordinary fact that having good and loving relationships physically alters your DNA. Conversely, a 2010 U.S. study found, not having such relationships doubles your risk of dying from any cause.
...And on not preventing disease
- Roughly 40 percent of people with diabetes, chronic hypertension, or cardiovascular disease were fit as a fiddle before they got ill, and roughly 20 percent of people who are severely overweight live to a ripe old age without ever doing anything about it. Just because you exercise regularly and eat a lot of salad doesn’t mean you have bought yourself a better life span. What you have bought is a better chance of having a better life span.
- A randomly selected American aged forty-five to fifty-four is more than twice as likely to die, from any cause, as someone from the same age-group in Sweden.
- Children in the United States are 70 percent more likely to die in childhood than children in the rest of the wealthy world. Among rich countries, America is at or near the bottom for virtually every measure of medical well-being—for chronic disease, depression, drug abuse, homicide, teenage pregnancies, HIV prevalence.
- now it seems we have reached a point of diminishing returns. By one calculation, if we found a cure for all cancers tomorrow, it would add just 3.2 years to overall life expectancy. Eliminating every last form of heart disease would add only 5.5 years. That’s because people who die of these things tend to be old already, and if cancer or heart disease doesn’t get them, something else will. Of nothing is that more true than Alzheimer’s disease. Eradicating it altogether, according to the biologist Leonard Hayflick, would add just nineteen days to life expectancy.
Just straight-up-interesting-facts
- The skin consists of an inner layer called the dermis and an outer epidermis. The outermost surface of the epidermis, called the stratum corneum, is made up entirely of dead cells. It is an arresting thought that all that makes you lovely is deceased. Where body meets air, we are all cadavers.
- Heinz ketchup is almost one-quarter sugar. It has more sugar per unit of volume than Coca-Cola.
- Most men, I daresay, have never heard of their epididymis and would be a little surprised to learn that they have twelve meters of it—that’s forty feet, the length of a Greyhound bus—tucked inside their scrotal sacs.
- Women who have had twins already are ten times more likely to produce a second set than women who have not.
- We don’t know what triggers birth. Something must count down the 280 days of human gestation, but no one has worked out where and what that mechanism is or what makes its alarm go off.
- Accidental discoveries made during routine investigations happen so often that doctors have a word for them: “incidentalomas.”