The Body - Book Summary

Unveiling the Marvel Within: The Intricate Wonder of the Human Body

Take a moment to ponder the marvel that is your body—a fusion of biology and mystery that even experts strive to understand. Your body is a world unto itself, complex and bizarre, something truly wondrous to behold.

Imagine embarking on an exploratory journey through your own self. You'll venture from the depths of the brain to the beats of the heart, and encounter the myriad of microscopic creatures that call you home. Prepare to dive into the enigmatic world of sleep, the challenges of achieving a nutritious diet, and the crucial role hormones play in steering desires and emotions.

Ready for a fascinating odyssey through the inner cosmos of the human form?

This exploration will unveil:

- The staggering cost of replicating an individual such as the acclaimed actor Benedict Cumberbatch from the ground up;

- The link between our evolutionary choice to walk upright and the agony experienced during childbirth;

- And the type of illness that stands as the most likely perpetrator of your eventual demise.

Let's begin the voyage within and marvel at the beauty and complexity of the body that is uniquely yours.

The Wondrous Alchemy of Building a Human Being

Have you ever considered the sheer complexity involved in constructing a human life from nothing? Imagine you have an empty canvas and your task is to create a person, molecule by molecule, starting from the very basics.

In a thought experiment as unusual as it was fascinating, the Royal Society of Chemistry calculated in 2013 the cost to assemble the famous actor Benedict Cumberbatch by tallying up the prices of 59 elements his body comprises. Most of the body is made of just a handful — carbon, oxygen, hydrogen, nitrogen, calcium, and phosphorous. But the price tag for these elements alone? A hefty sum of ninety-six thousand, five hundred and forty-six pounds and seventy-nine pence — not accounting for those tiny details like labor or taxes.

On a similar quest, the science show "Nova" from PBS suggested a ballpark figure much lower, at one hundred and sixty-eight dollars to put together a human. The staggering difference in estimates only underscores the uncertainty and complexity in evaluating the human body's worth by its base elements.

But let’s pause there. It's one thing to gather the elements — it's quite another to breathe life into them. Therein lies the sheer mystery of our existence. Even if we had all the necessary materials laid out before us, they would amount to nothing more than an inert collection. Life — that elusive spark — defies our grasp.

The beginnings of life, too, are shrouded in mystery. Consider the cell, the fundamental unit from which we are constructed. How do trillions of cells come to be orchestrated into a coherent, living being? The full orchestration of this biological symphony is still an enigma that evades scientific explanation.

But within the nucleus of each cell lies a wonder — a meter-long strand of DNA containing the codes that make you, well, you. This microscopic script is a narrative of your lineage, an uninterrupted publication authored over three billion years, passed on through countless generations.

To think of the body as merely a machine is to overlook its extraordinary enigma. This biological marvel works tirelessly around the clock without pause, sustaining itself for decades with little more than water and nutrients, all the while hosting the phenomenon of consciousness.

Reflecting on the human body's journey from a cluster of cells in the primordial seas to the complex entities we are today is to recount a tale of serendipitous events, each more incredible than the last. Indeed, our very existence is the culmination of cosmic coincidences — a sequence of spectacularly fortunate accidents.

Microbial Companions: The Crucial Inhabitants of Our Inner World

Imagine your body as a bustling metropolis, with trillions of microscopic inhabitants bustling through every nook and cranny, from the peaks of your scalp down to the soles of your feet. This isn't science fiction — it's the reality of our existence.

Trillions of minute creatures, around 40,000 different species, dwell within and on us, with about 900 species claiming the real estate within our nostrils alone. These tiny tenants play an indispensable role in our survival, contributing significantly to vital processes such as digestion.

It may seem surprising, but these minuscule organisms — our microbiota — are responsible for providing us with an additional 10 percent of our caloric intake by breaking down the food we consume. While the human body can produce a mere 20 digestive enzymes on its own, our gut bacteria produce a staggering 10,000. Our microbiota are so integral to our wellbeing that they could be likened to another organ inside us, one that plays a vital role in maintaining our health.

But bacterial cells aren't the only residents of our body's ecosystem. There are also viruses, archaea, fungi, and protists among us. Dana Willner's research at San Diego State University revealed that the average human harbors 174 virus species, with a vast majority yet to be classified. While the figure might sound alarming, it is a relief to know that out of the multitudes of viruses in existence, only 263 are known to cause diseases in humans.

Despite the array of microbial life within us, the number of harmful species is relatively low. Out of over a million identified, only 1,415 are known to pose a danger to us. However, these culprits are still linked to a third of all deaths globally.

Antibiotics like penicillin, derived from fungus, have been game-changers in our defense against harmful bacteria. Remarkably, today's penicillin strains can all trace their ancestry back to the mold on a single cantaloupe from World War II that was found to have potent antibiotic properties.

But this potent weapon comes with its drawbacks. Penicillin, while a formidable bacteria slayer, does not distinguish between the beneficial and harmful bacteria it encounters, causing collateral damage in our internal microbial communities.

Moreover, the miracle of antibiotics is threatened by an emerging crisis — resistance. Bacteria have evolved, growing increasingly resilient to our antibiotics due to overprescription and excessive use in agriculture. Nowadays, an average person in the West is prescribed antibiotics numerous times before reaching adulthood, a trend that only exacerbates the issue.

We stand at a crossroads where the power of antibiotics is waning, reinforcing the sobering truth that our existence is intricately bound to the microscopic lifeforms within us — for better or worse.

Within the Skull Lies a Marvel: The Power and Mystery of the Human Brain

Nestled within the human skull is a wonder that outshines almost anything else on this planet: the brain. It's a peculiar and mesmerizing organ: it's about 75 to 80 percent water, has a texture that's unexpectedly delicate, and remains cloistered from the world it allows us to experience.

This extraordinary organ isn't just idling away. It busts the mythical claim that we utilize only 10 percent of our brain at any one time — every bit of the brain is engaged. Consuming 20 percent of our body's energy requirements — and a staggering 65 percent for a newborn — the brain completes its myriad tasks with blueberry muffin-like calorie efficiency every day. Though we share the same basic brain components with creatures like dogs and hamsters, and our brain size is proportional to that of a mouse, the staggering number of neurons, approximately 86 billion, link and network in trillions of ways, conjuring the magic of the human experience.

The brain is segmented into three principal parts: the cerebrum, or the two-hemisphered director of senses, emotions, and character; the cerebellum, an unassuming back-of-the-skull entity housing over half of our neurons to choreograph balance and movement; and the brainstem, the life-sustaining bridge that paces our breaths and guides our sleep.

Among the brain's lesser-known regions lies the hypothalamus, a minuscule epicenter that commands our chemical symphony — it pulls the strings on desires, quenches thirst, appeases hunger, and might even hold the baton on the tempo at which we age.

In the century before last, the fledgling science community toyed with the notion that head shape and size might narrate facets of our persona, spawning flawed theories like phrenology and craniometry. Although misguided, they weren't completely off the mark in appreciating the head's captivating traits, which extend well beyond the cerebral chambers.

Our faces, for instance, are canvases capable of painting a vast repertoire of expressions. Among them are six universal dialects of emotion — fear, anger, surprise, pleasure, disgust, and sorrow. The smile, in its genuine form, is a global dialect, invariably understood across cultures and impossible to forge given that the muscles responsible for crafting it are beyond voluntary control.

Crowning our head's significance are the domiciles of our primary senses: sight, hearing, and smell. These senses are decoded, interpreted, and rendered into experience by none other than our unassuming yet extraordinary brain, the remarkable organ we so often take for granted, but one that continues to astonish and inspire awe.

Debunking Myths and Uncovering Truths About the Heart and Blood

Our hearts have been the center of many a myth, not the least of which is their alleged headquarters on the left side of the chest — when in fact, they reside closer to the center. And those cute Valentine's symbols we've grown accustomed to? They're far from the real, industrious shape of this vital organ. Romance aside, the heart’s pivotal role is to relentlessly pump blood, adding up to a staggering 3.5 billion beats over the course of our lives.

This muscular powerhouse, tipping the scale at less than a pound, undertakes the monumental task of circulating blood throughout the body. Blood's journey extends all the way down to the tips of the toes and back, defying gravity's pull with every forceful contraction of the heart, all while distributing approximately 260 liters of blood every hour.

Blood is so much more than simply a transport liquid. It ferries oxygen to myriad cells, shuttles vital chemicals, whisks away our cellular refuse, wards off infections, and assists in body temperature regulation. Given its rich and complex composition, it's no surprise that a single blood test can offer doctors a wealth of diagnostic information.

Within our blood flows a quartet of essential elements: plasma, red blood cells, white blood cells, and platelets. Plasma is the chief component, and it's mostly water but brimming with various essential substances. Red blood cells are the oxygen carriers, while white blood cells bear the crucial responsibility of infection defense. Platelets, once an enigma, have revealed their blood-clotting capabilities, and ongoing research hints at even more roles, possibly in tissue regeneration.

The history of blood treatment is littered with precarious practices, like the notorious bloodletting — which quite likely accelerated the demise of individuals like George Washington by reducing a significant percentage of their blood in an attempt to cure what was likely a mere throat infection.

Despite advances in medicine enabling blood transfusions, the undertaking remains intricate, and storing blood is equally challenging. The pursuit of artificial blood continues, with nanotechnology holding promise for the future. Yet, as of now, the heart continues its faithful rhythm, circulating a substance that defies exact replication by our brightest intellects. For all our progress, there is still much to learn and appreciate about the workings of the heart and the blood that sustains us.

Unlocking the Enigma of Hormones: The Body's Chemical Messengers

Traverse the intricate network of the human body, and you will uncover the silent whispers of hormones, delivering their chemical dispatches from one corner to another. Though immensely diverse, all hormones share a common purpose: to trigger actions across various bodily systems.

Research into the world of hormones has exploded since 1958, skyrocketing from a mere handful to over 80 known hormones today. This vigorous exploration underscores just how vital these substances are to our well-being.

Consider diabetes, a condition where the body fails to produce sufficient insulin, the hormonal guardian of our blood sugar levels. Not long ago, in the 1920s, a diabetic fate was grim, with rising sugar levels destined to end in death, and the only defense lay in abstaining from food. The synthetic production of insulin, however, changed the game, almost magically returning those afflicted to health and earning the process the allegory of a medical resurrection by Michael Bliss, who documented insulin's discovery.

The extraordinary life of Robert Wadlow offers a different tale of hormonal influence. This Alton, Illinois native surpassed eight feet in height by the end of high school and continued to grow due to his pituitary gland's overzealous production of growth hormone. Though his stature was extraordinary, it carried a tragic cost, leading to his premature death at 22 due to complications arising from his abnormal growth.

It's astonishing to contemplate that a gland no larger than a bean could exert such dramatic impacts on the human form. Yet, the story of Wadlow is an exception that we understand. Much of the hormonal world remains shrouded in mystery. Consider oxytocin, warmly dubbed the "hug hormone," which fosters feelings of love and affection but also, inexplicably, orchestrates the contractions during childbirth and plays a role in face recognition. What links these distinct functions? That remains one of the many secretive threads woven into the fabric of our bodies.

Hormones illustrate just how much we know about the body — and how much we have yet to learn. They influence every aspect of our biology, from the monumental to the minuscule, and continue to guard their secrets closely, waiting for us to unravel the next chapter in understanding the human condition.

Walking Tall: The Evolution of Bipedalism in Humans

Have you ever wondered about the architectural marvel that is the human skeleton? Approximately 206 bones compose this structural wonder, although there's personal variation — one in eight individuals may boast an additional set of ribs. And then there are the sesamoid bones, tiny seeds of structure woven into the hands, feet, and beyond, excluded from the usual bone count.

But these bones are far more than biological scaffolding. They safeguard our organs, craft blood cells, store essential minerals, and even, as discovered in the early 2000s, produce hormones like osteocalcin. This discovery shed light on how exercise, a bone-strengthening activity, might also diminish the risk of developing Alzheimer's disease.

The network of bones, muscles, and tendons is a marvel of biological engineering. Take the human hand as an example: it comprises 29 bones, 17 muscles, over a hundred ligaments, an intricate web of arteries and nerves, with an additional 18 muscles in the forearm dictating its movements. The hand isn't just functionally impressive — it's divinely complex, as once suggested by the surgeon Sir Charles Bell.

We often extol our opposable thumbs as a biological triumph, and while they are shared among primates, humans possess a unique triumvirate of thumb muscles empowering us with unparalleled dexterity in tool manipulation. These muscles, though significant, are often unknown by name, including the extensor pollicis brevis, flexor pollicis longus, and the understated first volar interosseous of Henle.

Bipedalism — walking on two feet — is another watershed in human evolution, as pivotal to our species as the complexity of our brains. To accommodate this upright lifestyle, we've developed increasingly lengthened necks, pliable spines, and robust knees, diverging significantly from our primate cousins. Yet, this evolutionary step has brought its share of maladies, such as chronic back pain, and revolutionized childbirth, giving rise to more excruciating labor due to narrower pelvises. Indeed, the birth process is a uniquely human ordeal.

In the eras of hunting and gathering, we spent a considerable amount of energy in the pursuit of sustenance, which favored an efficient means of mobility. Fast forward to today, where many of our days end with a slump onto the couch, it's essential to remember — our bodies are built to move. Even so, rest isn't to be undervalued; digestion and numerous other bodily functions necessitate moments of stillness. So, as you reach for the remote and settle in, rest assured, some downtime is part of the natural order.

The Culinary Art and Science: How What We Eat Shapes Us

Our culinary endeavors do more than satiate hunger or indulge the palate—they are a testament to our evolution and a demonstration of how we differ from our primate relatives. The very act of cooking has not only softened our food but also our anatomy, leading us to develop smaller teeth and a less powerful jaw. It also nullifies toxins, enhances flavor, conserves the time we’d otherwise dedicate to mastication, and improves the efficiency with which we harness energy from our meals.

Yet, nourishment transcends mere caloric intake; it's also about the meticulous balance of vitamins and minerals. These vital components, procured from both the living and the inanimate, are the chemicals our bodies yearn for but cannot self-fabricate.

The balance of macronutrients—carbohydrates, proteins, and fats—remains a debated topic. With everyone dining on a unique blend of food within their own distinct lifestyles, pinpointing specific dietary effects amidst a sea of variables is a formidable task.

However, the overconsumption of sugar is an undeniable issue. Consider the average American, ingesting 22 teaspoons of added sugar daily, compared to the World Health Organization's recommendation which caps at five. Such dietary excess isn't solely a product of modern fast-food culture; even fruits have been bred for heightened sweetness over time.

Once ingested, food embarks on a gastric journey, first marinating in stomach acid potent enough to neutralize most ingested microbes. The voyage continues through the small and large intestines, where nutrients are assimilated and fiber is decomposed by bacteria.

What remains, the unusable residue, exits as feces. Over a lifetime, the average person will produce nearly 14,000 pounds of this biological byproduct. Predominantly composed of bacteria remnants, undigested fiber, and sloughed-off cells from the intestinal lining and circulatory system, feces represent the tail end of our body's remarkable ability to utilize the sustenance we consume. The process underscores a simple yet profound reality—you are, quite literally, what you eat.

Circadian Rhythms: The Master Clock Within

The enigma of sleep captivates scientists and philosophers alike as we surrender to it for roughly a third of our existence. Sleep appears to be a master reset button for our memories, hormones, immune system, and more. Yet, the question lingers: why must we drift into unconsciousness to reap these benefits? As noted sleep researcher Allan Rechtschaffen once suggested, sleep is either vital to our survival or a baffling evolutionary blunder.

We are equipped with various internal mechanisms that signal when it's time to rest. It was only in 1999 when scientists uncovered a third variety of photoreceptor cells within our eyes, joining rods and cones. These newcomer cells — the photosensitive retinal ganglion cells — are luminescent sentinels that discern daylight from darkness. Remarkably, their presence permits even some individuals without sight to detect the presence of light.

Beyond detecting light, our bodies harbor a network of circadian clocks, each organ ticking to its biological rhythm, synchronizing its functions to the day's ebb and flow. These chemical timekeepers regulate everything from when our reflexes peak — typically in the mid-afternoon — to various other physiological and metabolic processes.

But our temporal perception is not bound merely to the daily cycle. Our brains, thanks to the pineal gland, are attuned to the rhythms of seasons too, echoing the cadence of hibernating creatures. Our physiological operations — take hair growth, for instance — shift subtly as the earth orbits the sun, with summer often hastening our tresses.

Even at the most diminutive levels of life, the presence of internal clocks is almost universal — an observation that prompted scientist Russell Foster, the man behind the photoreceptor cells discovery, to muse that such temporal regulation could be an intrinsic trait of living organisms.

The passage of life brings an evolution in our circadian cycles as well. Newborns might immerse in sleep for up to 19 hours daily, while the sleep requirements gradually wane with age. Hence, when teenagers struggle to rise with the dawn, it's not mere indolence; their internal clocks are genuinely desynchronized from the typical adult schedule. Understanding these rhythmic intricacies may bring us one step closer to unraveling the elusive purpose and mechanisms of sleep.

From Y Chromosomes to Childbirth: The Underexplored Terrain of Women's Health

The landscape of medical research is slowly but surely embracing the crucial differences between female and male biology, a field that remained neglected for far too long. The Y chromosome, discovered by Nettie Stevens in 1905, serves as a pioneer symbol of gender variations, though Stevens's contribution was overshadowed by her male contemporaries also unearthing the chromosome around the same time.

This pattern of oversight extends into modern medicine, with research traditionally being male-centric. It wasn't long ago that women were routinely excluded from drug trials, out of concern that their menstrual cycles might interfere with data — ironically ignoring the very real implications of these hormonal cycles on drug interactions.

It has taken centuries to begin unraveling the complexities of menstruation and menopause, and female anatomy has often been shrouded in ambiguity. The ongoing debate over the G spot's existence underscores the discrepancy in anatomical understanding between genders. By contrast, male anatomy, though more thoroughly studied, still harbors its own mysteries, such as the inconclusive data on average penis size.

Pregnancy and childbirth remain some of the most astounding processes yet to be fully decoded by science. Take the placenta, for instance, often dubbed the least understood organ. It stands as a vigilant guardian over fetal development, filtering out toxins, dispensing hormones, and acting as a barrier to potential threats. Many pregnancy complications trace back not to the fetus but to this enigmatic organ.

The onset of childbirth is enigmatic, marked by the sudden evacuation of amniotic fluid and the independent operation of the newborn's heart and lungs. This transformative moment brings a symphony of pain for the mother, as she delivers a child whose head typically surpasses the birth canal's width by a full inch.

Curiously, the very act of traversing the birth canal during delivery imparts the infant's first microbial encounter, passing on a crucial microbial legacy. Recent research hints at the potential long-term health implications for cesarean-born infants, who might face higher risks of conditions like Type 1 diabetes and asthma due to missed exposure to these maternal microbes.

These findings punctuate a broader narrative in medical research — a narrative marked by gaps in our understanding of female biology and an urgent need for deeper exploration into the wonders and workings of women's health and childbirth.

Shifting Tides in the Battle Against Disease

In the panorama of human health, 2011 marked a pivotal transition: deaths from non-communicable diseases, those that do not pass from person to person like heart disease and strokes, began to outnumber those caused by communicable diseases, such as infections. This shift not only reflects advancements in medical science but also underscores the growing influence of lifestyle choices on our health.

Historically, communicable diseases have claimed countless lives. In the West, we've managed to tame many such afflictions, with diseases like diphtheria, once a prolific killer, now nearly extinct in the United States. However, it's smallpox that stands out in our triumph over communicable diseases, a merciless killer eradicated in 1980 after it claimed the lives of around 500 million people in the 20th century alone.

Genetic maladies comprise around seven thousand known non-communicable diseases, such as pycnodysostosis—a rare condition thought to have affected the artist Henri de Toulouse-Lautrec, halting the growth of his legs at puberty. Afflictions like this, often confined to a small number of individuals, are commonly sidelined in research, leaving effective treatments elusive.

Professor Daniel Lieberman of Harvard introduces us to "mismatch diseases" — illnesses birthed from the incongruence between our evolutionary heritage as hunter-gatherers and our modern sedentary lifestyles. Diabetes and cardiovascular diseases are prominent members of this category, many of which could be mitigated or avoided altogether through healthier living.

Today, cancer looms large as one of our most daunting health adversaries, resulting from runaway cellular division turning our bodies on themselves. While treatments are progressively advancing, the complexities of cancer are vast, and the paths to cures are long and winding.

Pain is a notorious companion of cancer, yet it often arrives too late to serve as a warning. Dubbed "the apogee of pointlessness" by neuroscientist Patrick Wall, cancer-related pain exemplifies chronic pain, a dysfunction of the body's alert system. Unlike acute pain, which warns us of immediate harm, chronic pain serves no such protective purpose.

Our bodies, for all their complexity and wonder, are not without their flaws. Whether battling a disease that has persisted through the ages or confronting the consequences of modern living, it's evident that while we've come far in our medical conquests, the journey towards understanding and perfecting human health continues.

Measures of Mortality: The Inevitability of Life's End

Medicine's leaps in advancement since the early 20th century have drastically changed our prospects for health and longevity. As Lawrence Henderson, a venerable Harvard physiologist, poignantly observed, the odds of benefiting from a doctor's care crossed the fifty percent threshold for the first time around 1912, and have only improved since.

British epidemiologist Thomas McKeown made a groundbreaking observation in the 1960s: the decline in deaths from diseases like tuberculosis and measles began even before medical treatments were available, implicating enhancements in sanitation, nutrition, and transportation infrastructure in the overall elevation of public health.

Yet, with all our advances, immortality eludes us. The aging process, its causes shrouded in biological mystery, marches on indiscriminately. Daniel Lieberman suggests that a wholesome lifestyle could steer us toward the 80-year mark, but surpassing that typically hinges on our genetic script.

Speculation about the lifespan of contemporary youth varies wildly. While some experts forecast a future where living 50 percent longer becomes the norm, others entertain the prospect of reaching a millennium. Currently though, the centenarian club remains exclusive, with merely one in ten thousand individuals celebrating a one-hundredth birthday.

Globally, we witness around 60 million human departures each year — that's about 0.7 percent of the population. A segment of these exits are abrupt, another portion unfolds with little forewarning, and the majority are slower descents, as life ebbs away with the worsening of chronic conditions.

The cessation of life is a universally recognizable event. Interestingly, a deceased body harbors life still, as microbial inhabitants continue their existence. Nonetheless, the individual's personal odyssey, once animated by consciousness, draws to a close. Medicine may continuously push the frontiers of life expectancy, but the finitude of existence remains a universal human experience.

Embracing the Mysteries of the Human Body

Within the rich tapestry of scientific discovery, the human body remains a source of wonder and enigma. Our exploration has revealed astonishing facets of our physical being — from the trillions of microbes that aid our survival to the intricate dance of hormones regulating everything from emotions to childbirth. The feats of the brain, the steadfast rhythm of the heart, our evolutionary triumphs, and the triumphs yet to come in medicine and health all paint a portrait of a body that is a marvel of the natural world.

As science deepens its understanding, so too do we realize the vast expanse of knowledge that lies undiscovered. Our treatments, diets, and lifestyle choices can be optimized, influenced by the legacy of our evolutionary past and the promises of future research. Even as we decode the mechanisms of aging and disease, the ultimate mystery of existence — the sheer marvel that we live, breathe, think, and feel — remains a profound truth to ponder.

The essence of our bodily existence is this interplay between the known and the unknown, a journey of constant discovery that reminds us of the precious complexity and beauty of life.