Wondrous, Mysterious, Us

The human body is a wondrous miracle. From the way it functions as a whole, to the individual parts of the body, we never stop to think and consider how it works. Even scientists and doctors, who devote their lives to studying it, find it profoundly strange, complex, and even baffling at times. 

The Body: A Guide for Occupants (2019), by Bill Bryson is an entertaining account of facts that try to explain the functioning of the human body. It helps discover more about the body, right from the various organs such as the heart and brain, down to the hormones that play a vital role in regulating emotions and the sex drive, how sleep plays an ambiguous, role in keeping one healthy. It tells us why it is tough to manage a diet, and what role millions of microbes, living on and inside us, play.

Moreover, it is a journey that each and everyone should embark on to understand their bodies better.

Can We Make A Human?

Scientists have been trying to figure out what would it take to create a human right from scratch. 

The UK’s Royal Society of Chemistry took on a bizarre task in 2013 of estimating what it would take to build actor Benedict Cumberbatch. They calculated a requirement of 59 elements, with 6 elements – hydrogen, oxygen, carbon, nitrogen, calcium and phosphorous – needed in large quantities. They estimated a cost of £96,546.79, just for the elements, not counting labour and tax costs.

Another estimate by the US PBS network’s science program Nova estimated the cost of building a human at a mere $168 in 2012.

While the cost of elements can be debatable, it is the actual act of building a human that is still baffling. Even with all the necessary material at hand, how does one create life? 

No one has been able to specify where life actually begins. While science has pegged the cell as the essential unit of life, it still cannot explain how they coordinate to make the body function, how the genes and chromosomes in the body have been transmitted from generation to generation in the DNA, how the body survives – like a machine – without needing many repairs for decades and how it runs only on water and food?

The fact that the human body is conscious is a wonder in itself, in addition to the fact that it had evolved from only a few cells in the ocean. The evolution of the human body is a series of wondrous accidents.

The Body: A Guide for Occupants (2019), by Bill Bryson
The Body: A Guide for Occupants (2019), by Bill Bryson

A Trillion Microbes

Apart from water and food that the body needs for survival, it would never have even existed without the trillion microbes on and inside it.

About 40,000 species of microbes live in and on our body, of which 900 live in the nostrils alone. The microbes inside the intestines and gut are especially important considering that they give the body 10% of calories by simply breaking down the food we consume. While the human body produces only 20 enzymes, microbes can produce about 10,000 digestive enzymes. The sum of all the microbes on the human body, or the microbiota, practically functions like an organ in itself.

The microbiota contains viruses too. San Diego State University’s Dana Willner states that the human body has about 174 viruses, of which we know only 10%. The microbiota furthermore contains archaea or single-celled microorganisms, which thankfully, do not cause any diseases. It also contains fungi (that have very little effect on the body), and protists (all other microscopic organisms).

Of the trillion microbes that reside, only 1451 are known to be harmful to the body. While it is a good ratio of harmful to harmless, the 1451 disease-causing microbes account for about one-third of all deaths.

Penicillin proved to be an invaluable antibiotic for humanity. Produced in bulk in the US during WWII, it was a fungus that was scraped off a cantaloupe, proving to be highly potent in killing bacteria. All the penicillin we have today descends from that one melon.

While its bacteria-killing function is brilliant, its very efficacy in killing microbes has also proven to be detrimental. Penicillin works on the bad bacteria, true.  But it also kills the good bacteria the body needs. Additionally, since bacteria develop resistance over time, increased use of antibiotics render medications ineffective over time.

The real problem though lies in the fact that antibiotics are too commonly prescribed world-over. In the West, an average person receives antibiotics at least 5 to 20 times before reaching adulthood. Antibiotics are being prescribed to farm animals in large quantities too, adding to antibiotic resistance. This is a looming threat and humans are at the mercy of these microscopic organisms.

The Human Brain

There isn’t anything in the world that is more extraordinary than the human brain. The brain, hidden away inside the skull, is strangely soft and made up of 70-85% of water. It is unique and amazing both, by structure and function.

The saying that humans do not use more than 10% of their brains is a myth. Humans not only use the whole brain all the time but also spend about 20% of their entire energy on it. Babies use 65% of their entire energy to keep the brain functioning. 

In terms of its size and material, it is no different from the brains of animals such as dogs or hamsters, but its efficiency and uniqueness are attributed to the 86 billion or so neurons it contains that form trillions of connections with each other. 

The brain is divided into 3 main sections, 

  • The Cerebrum – The home of all sensory processing, personality, and emotion, it is split into 2 hemispheres.
  • The Cerebellum – Containing more than half of the neurons in the brain, it is responsible for movement and balance.
  • The Brainstem – Connecting the brain to the spine and the rest of the body, the brainstem regulates functions such as breathing and sleeping.
  • The Hypothalamus – Peanut sized, it controls the chemical functions of the brain and regulates sexual drive, hunger, and thirst, and how we age. 

Earlier in the 19th century, the disciplines of craniometry and phrenology emerged due to the belief of some scientists that the size and shape of one’s head can help deduce some aspects of one’s personality. 

While these disciplines were termed bogus later on, it is still true that the human head has many amazing features.  The head houses the organs responsible for the 3 key senses – sight, smell, and hearing, which are in turn processed by the brain.

The face has the amazing ability of expressivity. While there is a multitude of expressions, there are 6 universal ones, namely – pleasure, anger, disgust, fear, sorrow, and surprise. Without to ability to independently control the muscles that generate these emotions, no human can fake them.

The Heart And All That Flows Within

Ironically, the heart symbol that is a unanimous expression of love world-over, has no connection to the human heart whatsoever. There is nothing romantic about its shape and neither does it have any connections with emotion. Our notion of its placement to the left of the chest is wrong too.

Yet its remarkability lies in the single, crucial job it does – pumping blood through the body.

Placed more towards the centre, the heart beats an average of 3.5 billion times through an average lifespan and pumps about 260 litres of blood per hour. One powerful thrust of the heart sends blood down 4 feet on average, and then travels back up against gravity, carrying oxygen, transporting chemicals, killing pathogens, eliminating waste and regulating body temperature, all at once! It is a multifaceted function, and a complicated one too, enabling doctors to gain a lot of information through just one blood test.

Blood is made up of four main components.

  • Plasma is the main component of blood, containing various chemicals in 90% of water.
  • The red blood cells are the oxygen delivery boys.
  • White blood cells are the infection-fighting army.
  • Platelets help the blood clot and also help in regenerating tissue.

Today, we casually throw around sentences discussing blood transfusions, without realising how complex the procedures that doctors perform really are. 

Earlier, blood treatments were emblematic of the lack of knowledge we had about blood. George Washington is an important example of this. During his treatment, doctors had let out about 40% of the blood within 2 days; while the world still thinks he died of a throat infection.

Today, our understanding of blood is much better, enabling us to transfuse, store, and even try to create artificial blood (though with little success). Medical advancements aside, we can rest in the knowledge that the heart will go on… pumping what some of the worlds finest cant completely reproduce yet!

Mysterious Hormones

Hormones are truly mysterious. Though they lie in one part of the body, they have the ability to cause effect in another part, by delivering chemicals to different parts of the body. Hormones are diverse and scientists have only recently begun studying them. 

Diabetes is a classic example of how hormones affect the body. Diabetes is caused when the body is unable to produce enough insulin, making the body unable to regulate sugar. Diabetics before 1920 lived a death sentence, with stopping eating being the only defence.

In his book The Discovery of Insulin, Michael Bliss calls the discovery and the ability of scientists to produce insulin, a resurrection for all mankind. The effects of administered insulin were miraculous – a medical triumph.

Robert Waldow of Illinois is another example of the wonders of hormones. Being the tallest person that ever lived, Waldow was over 8 feet tall when he graduated and 8 feet 11 inches tall when he died at the age of 22 of a septic infection he caught due to his leg braces, meant to support his height. He kept growing taller due to a problem in his ‘baked bean-sized pituitary gland that produced too much growth hormone. It is amazing to think that such a small organ can have such huge effects.

Hormones are still a mystery to humankind. While some effects can be explained, many remain mysterious. Oxytocin, for example, is known for generating feelings of affection. However, it also helps direct contraction of the uterus during labour and also helps in facial recognition. The how and why of the connections of these tasks are still a mystery.

The Unique Skeleton

The human body has 206 bones. However, one in every eight people has a thirteenth rib. Additionally, the body also has sesamoid bones – or bones that are sesame-sized – near the hands, feet, and the rest of the body that aren’t counted.

We know for sure that the bones give the body structure, protect the inner organs, store chemicals, and make blood cells. However, in the early 2000s, it was discovered that bones also produce a hormone called osteocalcin, the reason why regular exercise also reduces the risks of Alzheimer’s.

The hand has 29 bones, 17 muscles, 123 named ligaments, and assorted arteries and nerves. Additionally, the forearm has 18 muscles that control these. The manner in which all these are connected and function is so amazing that Sir Charles Bell, the 19th-century Scottish surgeon called flexibility that ensues from these connections proof of divine creation. 

While most primates have an opposable thumb, humans have a unique trio of muscles –the extensor pollicis brevisflexor pollicis longus, and first volar interosseous of Henle – in the thumb that enables effective manipulation of tools.

Bipedal ability also makes humans uniquely different from primates, perhaps as important as the differences in the brain. Evolution, particularly of the long necks, suppler backs, and bigger knees than other primates has enabled humans to walk upright.

However, the same unique evolution of bipedal ability has evolved women to have narrower pelvises. Childbirth for humans is thus uniquely (and excruciatingly) painful and dangerous as compared to other primates. 

Evolutionarily, humans are made for movement. Being hunter-gatherers and being on the move always for procuring food used up a lot of energy. Thus, we can’t digest food while exercising. A positive excuse for couch-slouchers if there was ever one!!

We Are What We Eat

The digestive system of the human body works primarily to kill all the harmful bacteria we ingest. The hydrochloric acid in the stomach kills microbes and helps in further softening the cooked food that is chewed. The food then progresses down to the intestines, where nutrients are absorbed, and bacteria break down fibre.

What isn’t useful comes out of the body as faeces. Faeces are made up of undigested fibre, dead cells from the blood and the intestine, dead bacteria. From all that we consume, that is all that is left. The body is adept at using everything else.

Eating, today, is considered more as a way of satisfying one’s gastronomic pleasures; however, the primary function of eating is to attain energy. Cooking food helps in extracting more energy from the food we eat. Additionally, we need to eat to ensure the body gets its nutrients such as vitamins and minerals from outside sources, as it cannot make these itself. 

Today, the concept of dieting is immensely popular world-over. Despite the innumerable diet plans and methods available, dietary science is still flawed. The body needs the essential five – carbs, proteins, vitamins, minerals and fibre, and it is impossible to ascertain who needs how much of these as every person has a different body make and lifestyle.

However, there is one thing certain. Humans consume much more sugar than they need to. Considering all that the body uses from the food consumed, we need to stop and think – how much sugar are we letting the body consume.

The problem lies not only in the fast-food culture that has taken the world by storm. Even the average fruit has been enhanced and produced to taste sweeter. The WHO recommends only five teaspoons of added sugar a day as the upper limit for consumption. The fact that the average American consumes 22, counting the amount consumed in processed foods is alarming. The odds are certainly stacked against humans, and habits are to blame!

Sleeping Right

We spend about a third of our lifetime sleeping. No one has been able to pinpoint the importance of it. Yet, sleep does so much for the human body. It helps reset the immune system, hormones, our memories, and much, much more.

We lose consciousness when we sleep. While there must be a sound reason for it, no one really knows it. Sleep researcher Allen Rectschaffen, says that sleep either does something very important or is an evolutionary mistake of unique proportions.

There are many processes that help indicate sleeping time to the body. Along with the rods and cones in the eyes, it was discovered in 1999 that the eyes have a third photoreceptor – the photosensitive retinal ganglion cells. These detect brightness, telling the body when its night and day. These cells can also help some blind people know when light is switched on or off. 

The body also has a number of internal circadian clocks – chemical mechanisms found in the pancreas to the kidneys, that respond to the time of the day. Different circadian cycles have their own schedules: one such cycle, for example, prescribes that our reflexes are best in the middle of the afternoon.

The pineal gland in the brain tracks seasons, similar to hibernating animals. This makes the body function differently in different seasons. The faster growth of hair in the summer is one such example.

In addition, stages of life have different circadian cycles. The amount of sleep a human need decreases as we age. A baby needs about 19 hours of sleep, whereas, it is commonly found that the elderly suffer from a lack of sleep. Young adults need more sleep than they usually get, and hence, teenagers seem to be lazier than their parents. 

Women And Childbirth

Sexism has, unfortunately, affected gender sciences too. Women have been studied far lesser than men have. In fact, Nettie Stevens, the female scientist who discovered the Y chromosome that men have and women don’t, did not even get the credit for her discovery because a man discovered it too, roughly at the same time in 1905.

Until recently, a number of drug trials have excluded women due to the fact that menstrual cycles could skew their results. However, it is essential to account for menstruation in drug trial results. It is an important determiner why some drugs affect women differently.

While the male anatomy has been widely researched, the female anatomy is grossly under-researched. Menopause and menstruation were not studied at all.

Childbirth and pregnancy are under-researched too. For example, the placenta plays a vital role in the development of the foetus. It filters toxins, kills anything that could harm the foetus and even distributes hormones. Yet it is one of the least understood organs. Most of the problems women face during pregnancy result from problems in the placenta rather than the foetus itself.

Childbirth itself is miraculous and strange. Just as the womb drains away from the amniotic fluid, a baby’s heart and lungs start working. No one yet knows what triggers it. 

A newborn baby’s head is, on average about an inch wider than the birth canal, owning to why childbirth is so excruciatingly painful. 

Another wondrous thing about the body and childbirth can be seen in the long-term effects of birthing a baby naturally (through the birth canal) and via Caesarean section. Though still developing, research indicates that microbes present in the birth canal could be the reason why children delivered via the Caesarean section could have a greater chance of developing Type 1 diabetes and asthma. Exposure to a mother’s microbes may make a notable difference to the long-term health of individuals.

Fighting Diseases

We have treaded a long successful path when it comes to fighting diseases. In fact, 2011, a notable year in the history of fighting diseases, saw more deaths from non-communicable diseases than communicable ones. Deaths due to stroke and heart failure topped lists, whereas there were lesser deaths caused by viruses. This can be attributed to medical sciences as well as changes in lifestyle.

Earlier, communicable diseases wreaked hell on humanity. Diphtheria once killed as many as fifteen thousand people a year in the US alone. Today, deaths caused by diphtheria are rare. Medical sciences have been able to render smallpox – one of the world’s most rampant infectious diseases  – extinct as of 1980.

Science knows about seven thousand non-communicable genetic diseases. Furthermore, there are some non-communicable diseases, which are extremely rare. pycnodysostosis is one such example, where the growth of the legs stops after puberty. There have been only 200 known cases so far. Diseases such as pycnodysostosis, due to their rarity aren’t studied as much and thus have no effective treatments.

Professor Daniel Leiberman of Harvard also names a category of diseases mismatch diseases. These diseases are caused due to the discrepancy between current lifestyles and the evolution of the human body to match the hunter-gatherer lifestyle of our ancestors. Cardiovascular diseases and Type 2 Diabetes are examples, where changes in lifestyles can help avoid them.

Another disease that instils fear among humans is cancer. The study of the uncontrollable division of cells that causes the body to attack itself is still in its nascent stages, despite having improved treatments year on year. Cancer, according to Neuroscientist Patrick Wall, is the ‘apogee of pointlessness’. The pain caused by cancer in the later stages, and chronic pain (though a veritable indication of danger) are examples of how the body, though wondrous and miraculous, can malfunction anytime.

The Inevitability Of Death

According to Harvard physiologist Lawrence Henderson, at some point between 1900 and 1912, the chances of a patient having a successful doctor’s visit improved by 50%. Medical progress kept improving from that point onwards.

British epidemiologist Thomas McKeon hypothesized that since the beginning of the 19th century, in addition to improvements in medicine; there was a clear improvement in living standards such as better sanitation, better diet (owing to the fact that railways facilitated the delivery of fresher food to many places). The decline in deaths caused by a number of diseases including measles and tuberculosis started even before the treatments were available.

Scientists still do not know why humans age. However, treatment for diseases is only a temporary solution to stave off death. The lifespan of an individual depends on a number of factors. However, according to Lieberman a person, on average, can live till the age of 80 following a healthy lifestyle. However, the chances of an individual living longer than that depend on genes.

There are many theories stating that today’ younger humans will be able to live 50% longer in the future. But we are still a long way from turning these theories into reality.


The human race has come a long way in discovering some of the secrets of the human body. Medical sciences have unlocked the mysteries of many functions of the body. Despite the discoveries and the knowledge we have gained, it still amounts to a mere drop in the vast ocean. 

We still have much to learn and understand about the functioning of the human body, the diseases that affect us, and the world surrounding us.