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The Body book summary

The Body book cover

Human cells

  • All together it takes 7 billion, billion, billion atoms to make The Body. No one can say why those atoms have such an urgent desire to be you, they are mindless particles, without a single notion or thought between them. Yet somehow for the length of your existence, they will build and maintain all the countless systems and structures necessary to keep you humming, to make you. To give you form and shape and let you enjoy the rare and supremely agreeable condition known as life.
  • What is perhaps most remarkable is nothing is in charge. Each component of the cell responds to signals from the other components.
  • I’ve said it before in another book, but I believe it’s worth repeating: the only thing special about the elements that make you is that they make you. That is the miracle of life.
  • The most remarkable part of all is your DNA. You have a metre of it packed into every cell, and so many cells that if you formed all the DNA in your body into a single fine strand it would stretch ten billion miles, to beyond Pluto.


  • Biologically, there is no such thing as race—nothing in terms of skin color, facial features, hair type, bone structure, or anything else that is a defining quality among peoples.

The brain

  • It's a myth that we only use 10% of our brains.
  • Just sitting quietly, doing nothing at all, your brain churns through more information in thirty seconds than the Hubble Space Telescope has processed in thirty years. A morsel of cortex one cubic millimeter in size—about the size of a grain of sand—could hold two thousand terabytes of information, enough to store all the movies ever made, trailers included, or about 1.2 billion copies of this book.
  • 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.
  • The great paradox of the brain is that everything you know about the world is provided to you by an organ that has itself never seen that world. The brain exists in silence and darkness, like a dungeoned prisoner. It has no pain receptors, literally no feelings.


  • The most universal expression of all is a smile, which is rather a nice thought. No society has ever been found that doesn’t respond to smiles in the same way.
  • It is not true that there are certain areas of our tongue dedicated to different tastes.
  • The tongue doesn't tell me whether something tastes good. It is the brain that creates a story that tells me what I am feeling.


  • Our eyes contain two types of photoreceptors for vision—rods, which help us see in dim conditions but provide no color, and cones, which work when the light is bright and divide the world up into three colors: blue, green, and red.
  • Because we were once nocturnal, our ancestors gave up some color acuity—that is, sacrificed cones for rods—to gain better night vision. Much later, primates re-evolved the ability to see reds and oranges, the better to identify ripe fruit, but we still have just three kinds of color receptors compared with four for birds, fish, and reptiles. It’s a humbling fact, but virtually all nonmammalian creatures live in a visually richer world than we do.

Body clocks and sleep

  • Most of us have experienced that abrupt feeling of falling while asleep known as a hypnic or myoclonic jerk. No one knows why we have this sensation. One theory is that it goes back to the days when we slept in trees and had to take care not to fall off. The jerk may be a kind of fire drill.
  • We have body clocks not just in the brain but all over—in our pancreas, liver, heart, kidneys, fatty tissue, muscle, virtually everywhere—and these operate to their own timetables, dictating when hormones are released or organs are busiest or most relaxed. Your reflexes, for instance, are at their sharpest in mid-afternoon, while blood pressure peaks toward evening.

Microbes and antibiotics

  • 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.
  • The use of antibiotics are overly excessive. Almost 3/4 of the 40 million antibiotic prescriptions in the USA are for conditions that can’t be cured by antibiotics. Antibiotics for example are prescribed for 70% of bronchitis cases even though guidelines specifically state they are no use there. Even more appallingly, 80% of antibiotics are fed to farm animals, mostly to fatten them.
  • We are looking at a possibility where we can’t do a hip replacement or other routine procedures because the risk of infection is too high. The day when people die once again from a scratch or a rose might not be too far away.

Food & Agriculture

  • Many of our fruits and vegetables are nutritionally less good for us than they were even in the fairly recent past.
  • The difference between 1950 to today, modern fruits are about 50% poorer in iron than they were in the early 1950s and about 12% down in calcium and 15% in vitamin A. Modern agriculture practices it turns out, focus on high yields and rapid growth at the expense of quality. The US is left in the bizarre and paradoxical situation, that its citizens are essentially the world’s most overfed people, but among the most nutritionally deficient ones.


  • If someone invented a pill that could do for us all that a moderate amount of exercise achieves, it would be the most successful drug in history.
  • Today the average woman in the USA weighs as much as the average man in 1960. In that half century, the female is 63.5kg to 75.3kg. The man from 73.5kg to 89kg. The annual cost to the American economy in extra health care for overweight people is 150 billion, more than half of today’s children are expected to be obese by age 35.


  • By one reckoning, life expectancy on Earth improved by as much in the 20th Century as in the whole of the preceding 8000 years. The average life span for an American male went from 46 in 1900 to 74 by 2000.
  • The bottom line for credit for improved life spans is that nearly all of us are better able today to resist the contagions and afflictions that commonly sickened our great grandparents, while having massively better medical care to call on when we need it. We have never had it so good.
  • Nothing in medicine is simple, however, and there is an additional consideration that profoundly contributes to all medical data: over treatment. Most of history the focus of medicine is to make sick people better, but now it is now more about prevention.

The End

  • In 2011 an interesting milestone in human history was passed. More people died from heart disease, stroke, diabetes than all infectious diseases combined. We live in an age in which we are killed more by lifestyle.

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