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Key insights from
The Body: A Guide for Occupants
By
Bill Bryson
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What you’ll learn
The majority of you is made up of six elements, and 99.9% of
your DNA is exactly the same as everyone else’s—yet, both the human body
and you are unprecedented mysteries. We’re the only organisms to cry out of
sadness, and our brain shows us the future a fifth of a second before it
actually happens. Enigmas like these riddle human anatomy and continue to
baffle microbiologists, neuroscientists, and psychiatrists alike.
Bestselling author Bill Bryson details the vivid story of the human body,
drawing upon eye-opening facts—like the one that says our eyes don’t really
see a majority of what we think they do—and scientific research to lead us
further into the discovery of ourselves and the world of us.
Read on for key insights from The Body: A Guide for Occupants.
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1. We feel the
world through our skin, the largest organ of the body.
Have you ever experienced that annoying itch that just won’t
go away no matter how hard you scratch? So did a woman referred to as M.,
who in getting rid of that irritating skin sensation, actually scratched
straight through to her brain. She didn’t even realize she was doing it,
either; most of her itching took place while she was asleep. Don’t worry,
though—this is a medical anomaly. Still, it speaks to the greater mystery
of the human body since scientists not only have no clue why M. simply
couldn’t satisfy her itch, but they also have no idea why we even
develop an itch in the first place.
Despite the inevitable mystery surrounding our human
anatomy, there’s plenty scientists do know about skin. For instance, skin
is our largest organ, and it’s a part of something called the cutaneous
system which houses both our dermis and our epidermis. Rather morbidly, the
author notes, our epidermis, or the outer portion of our skin, is made up of
entirely dead cells. The inner layer of your skin is the dermis, and it
contains receptors that allow you to experience the world. Some of these
receptors are called Meissner’s corpuscles, the kinds of sensors that allow
you to pick up on the most delicate touch, like on your fingertips or your
lips. How you perceive the world through your senses is due largely in part
to these sensors, but the brain also plays an integral role. The author
notes that your brain actually tells you how a touch should feel depending
on who or what it’s coming from and the setting you are in.
The science of skin also proves that race doesn’t really
exist. According to paleobiologist Nina Jablonski at State College in
Pennsylvania, what we see as race is accounted for by a single tiny
molecule that adds color to our skin and to the features of various
animals. This molecule is called melanin, and it’s the source of differing
skin tones, the only known biological difference in people of different
racial backgrounds. Due to a process called phenotypic plasticity, skin
tones evolved in the past according to the particular environment the
person lived in, and continue to change now in response to sun exposure.
The author observes that melanin is what gives us dark freckles after a long
day in the sun, as our body works to protect us from the harmful rays.
Our skin is a powerful mechanism that does more than simply
keep our organs in place. While there’s still much to discover, like why
exactly we have dermatoglyphics (those are fingerprints), what we do know
about skin is scintillating.
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2. You aren’t as
clean as you think—you have 40,000 species of microbes in your body right
now.
Bacteria, fungi, viruses—these are just a few of the
microbes that make you uniquely you. If it wasn’t for bacteria, we wouldn’t
be able to breathe. The author notes that 80% of the air we fill our lungs
with is actually nitrogen, not oxygen. Bacteria are the microbes that
convert this into something we can use. Out of the 40,000 types of microbes
floating inside you right now, only 1,415 actually lead to diseases.
Viruses like the common cold may seem threatening, but
science proves that they’re much more common than we think. In 1900 while
studying tobacco plants, a botanist and the world’s first ‘virologist,’
Martinus Beijernick, discovered a microbe smaller than any bacteria. It was
a virus. To have an impact on organisms, viruses must find a place within a
cell. Fortunately for us, most viruses lodge in bacterial cells and have no
outward impact on our health. There are exceptions to this, of course, and
one of them is the infamous virus known simply as the ‘common cold.’
Despite valiant attempts at avoiding this virus through efforts such as
washing your hands every time you touch a door handle or keeping hand
sanitizer with you at all times, the cold is nearly impossible to elude.
Immunity from the common cold is so difficult to attain because this virus
is actually an accumulation of various kinds of viruses.
Bacteria can be equally challenging to get rid of despite
the fact that some of them have a positive impact on your body. You’ve no
doubt heard of penicillin and the story of its accidental discovery by the
renowned Alexander Fleming in the 1930s, but you may not know that all
penicillin produced today is derived from one moldy cantaloupe. It was
still extremely difficult to make penicillin after its discovery, so in the
1940s, pharmaceutical researchers sent requests to fellow scientists to
bring in any mold samples they found. A woman named Mary Hunt responded to
this request, and pharmaceutical companies have been fueled ever since.
This was a breakthrough in modern pharmaceuticals, but its side effects
aren’t all promising to our health.
Unfortunately, antibiotics are prescribed to cure a wide range
of infections, even those that are not bacterial and are proven to be
unresponsive to such medicine, like viral maladies. Over time, our microbes
learn how to resist these antibiotics until they’re practically useless.
Increased resistance is in turn passed down through bacterial generations,
which means that no one is immune from the impacts of a societal
overreliance on antibiotics. Estimates predict that deaths due to
antibiotic resistance will grow to ten million, making the issue a
wide-reaching public health dilemma that people must become aware of.
The human body is both healer and protector, waging
countless tiny wars inside us. As stewards of so much, we must be
thoughtful and informed about what we put inside our bodies. Even something
as small as a microbe can change us.
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3. You have a
personal internet in your head; Nature Neuroscience says that your brain
carries 200 exabytes of knowledge.
Weighing in at just three pounds, your brain uses
approximately 20% of your energy to construct the world as you know it.
Memory, color, reality, thinking—your brain dictates the functioning of
each of these experiences. Inside your brain are cells called neurons,
which are complete with an axon tail and dendrites that branch out from
there. Neurons communicate with each other through synapses, and this
determines intelligence. The cerebrum at the top of your brain is separated
into two hemispheres with four regions called the frontal, parietal,
occipital, and temporal lobes. Located at the back of your head right
beneath what you see when you think of the brain is the cerebellum, which
is also right near the brainstem. The brain helps us know our world, yet
itself cannot be known.
Scientific studies and medical history prove that the region
of your brain called the frontal lobe dictates a large portion of who you
are as an individual. Human nature and personality cannot be confined to
the brain, but science does tell us some pretty interesting things about
ourselves. The frontal lobe is in charge of our emotional functioning, our
thinking, and various other factors that comprise who we are as people.
Unfortunately, scientists failed considerably before landing on this
discovery. Before we knew the impact the frontal lobe has upon human
personality and mental well-being, scientists developed a procedure meant
to reduce ailments ranging from epilepsy and schizophrenia to OCD and
general disobedience. In 1949, the doctor Walter Jackson Freeman adopted
the methods of neurology professor Egas Moniz and popularized the frontal
lobotomy throughout the United States. The process was excruciating and
left people depleted of individuality and uniqueness.
Thankfully, the 1960s brought about Freeman’s retirement and
the end of the lobotomy. Neuroscience is still a long way from
understanding the brain in its entirety (if that’s even possible), but it
has progressed greatly from brutal and unethical medical procedures to
practices that recognize the frailty and value of all human beings, no
matter how quirky or disobedient.
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4. Historically,
bleeding was seen as a cure-all—people believed that releasing blood
released illness.
Our blood has a rather winding history, much like the 25,000
miles of blood vessels that wrap and wind throughout our body. Within our
blood are red cells, white cells, platelets, and plasma. While red blood
cells are plentiful in our veins, delivering oxygen to the rest of our
body, white blood cells make up less than 1% of our blood and are
responsible for waging war on diseases, viruses, and any other threatening
force that finds itself inside us. The majority of our blood consists of
plasma, which delivers various nutrients and other necessary components
throughout the body. Additionally, platelets help our blood clot when we
experience cuts or other causes of bleeding. Each of these components is as
necessary to blood as blood is necessary to life.
Now imagine a world in which esteemed doctors believed that
in order to cure a patient of, say, a simple sore throat, one must drain
the body of its blood, its life force and source of vitality. The author
notes that medicine up until the 19th century was approached in a more
holistic way. A simple cold signified a more widespread ailment, and in
order to address the sickness in its fullness, it must be treated on the
bodily level. That’s where the method of bleeding was introduced, along
with various other treatments that expunged the body of any presumed
illnesses. George Washington himself suffered an agonizing death through
bleeding for a sore throat with the loss of 40% of his blood. Another
American leader, the highly intelligent and fatally misled doctor Benjamin
Rush was known as the “Prince of Bleeding,” and he administered bleeding
treatments to many until his eventual death by bleeding as well. It’s easy
to view these treatments as ridiculous, illogical displays of scientific
ignorance, but at the time, very little was known about blood, and this
procedure was lauded as a common cure-all. In all things, medicine
included, darkness precedes clarity, and ignorance is a prelude to understanding.
Still, even today with our progressive science and medical
know-how, there remain gaping holes in our knowledge. Currently,
researchers like Dr. Allan Doctor at Washington University are
experimenting with ways to create artificial blood through nitric oxide in
hopes of avoiding the danger of real blood transfusions. Their efforts have
proven unsuccessful so far, so doctors are simply limiting the number of
blood transfusions to mitigate any danger.
Despite the fact that there’s still so much left to improve
upon, at least we’re miles away from the days of injecting humans with
wine. And it’s good to hold onto our blood, too; we may need it, after all.
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5. Take a walk,
then a nap: frequent movement and regular sleep are vital.
Despite the importance of exercise and rest to your overall
bodily health, a majority of people are failing to get enough of
either—only 20% of people engage in adequate regular activity, and the
average amount of sleep has decreased from eight-and-a-half to seven hours
per night. This is a plague with the potential to cancel any efforts you
make to remain healthy through proper diet and nutrition. Movement and
sleep simply cannot be replaced. In fact, our bodies were literally born to
run.
Due to the nuchal ligament located at the back of the skull
and the neck, the mechanism that maintains the balance of your head, the
author notes that we are made to run long distances. If that sounds like a
little too much movement for you, don’t worry, walking can be just as effective
to your health. After a long, immobile day at work, nothing is more welcome
than stretching your legs for an hour outside, especially as the sun’s
setting and the sky’s darkening. The author notes that daily walks decrease
the rate of having a heart attack or a stroke by an astounding 31%. And
it’s so easy, too. There’s no need to head out on a long run, unless you
want to, of course—the benefits of that are even more plentiful. A study of
joggers in Denmark showed that those who run often actually live five to
six years longer than those who do not. While there may be several
confounding variables in studies like these, the main point is inarguable.
For better health, sit less, and move more.
After that long walk, make sure to get a refreshing night’s
sleep, too. Though we spend one-third of our lives curled up in bed,
researchers have no clue why sleep is so integral to our health. Everyone
knows that feeling of needing sleep so badly it’s as if a weight was placed
on your eyelids. That sensation is called sleep homeostasis, the building
desire to fall asleep due to an accumulation of chemicals in the brain.
Imagine never being able to slip into that detoxifying, restorative state;
illness, confusion, and general discomfort would abound. In 1986, a new
disorder was uncovered in a family of people who literally could not sleep.
This wasn't your typical case of pulling an all-nighter, either. Rather, it
was a case of what is now known as fatal familial insomnia, a rare
condition in which the victim’s thalamus is attacked by a protein called a
prion, ending in her inevitable death due to complete exhaustion. While the
condition is a rare medical anomaly, it attests to the absolute necessity
of sleep.
Our bodies always know something we don’t. Science may not
know why we need sleep, or exactly how much exercise is the optimal amount,
but still, it proves that movement and sleep contribute greatly to our
quality of life and health. So next time you’re feeling restless, listen to
your body and go for a walk. You need it more than you know.
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6. Your cells get
older, too—aging is inevitable on the molecular level.
In 1937, Gunda Lawrence was perhaps the most fortunate
cancer patient and mother alive. Both her sons had occupations in science,
but one of them, Ernest Lawrence, was an esteemed physicist at a radiation
lab which had access to a powerful X-ray machine. The two sons targeted
their mother’s stomach and shot a deuteron beam into the core of her cancer.
In a poetically moving and medically groundbreaking act, two sons healed
their dying mother and started what is now known as radiation treatment.
Stories like this abound in 20th century medicine. During this
century, medical science experienced rapid growth. Though cancer became the
second most common cause of death in the early 1900s, this shift only came
about due to a decline in infectious diseases. Now, even cancer rates have
seen a decline, dropping by 25-90% in the last 25 years.
Despite greater life expectancy, more hygienic lifestyles,
and various treatments for diseases and illnesses of all kinds, death is
fundamental—our cells actually put the process of getting older on full
display. In 1961, scientist Leonard Hayflick found that in experiments,
cells appear to divide up until a certain point and then die shortly after.
This is now known as the Hayflick limit, and it was further expanded to
show that as cells are dividing, things called telomeres decrease to a
particular length. Telomeres are DNA located at the bottom of chromosomes,
and their function is also thought to be a possible link to finding a
stable cure for cancer. Though the process of growing old was thought to be
just another facet of human experience conquerable by science, our cells
say otherwise.
Still, there are measures we can take to prolong our life
and lengthen our telomeres. Kind, compassionate, and loving relationships
are proven components of extending both the quantity and quality of your
years on earth. Your son might not be a world-famous physicist, but lasting
relationships with loved ones will prevent and heal a whole host of
illnesses.
The human body is truly a miracle, a puzzle that confounds
the greatest scientific minds of today. Thankfully, we don’t need to
understand it all to live—the body does that all for us.
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