Viewing Life and Illness from Multiple Perspectives

A monk asked the Buddha: What is greatest in strength? What is clearest in wisdom?

The Buddha said: Forbearance and patience bring great strength, because one harbors no ill will and is additionally peaceful and healthy. Those who forbear have no evil and will surely be respected by others. When mental defilements are utterly extinguished, pure and flawless, that is the greatest clarity. From before heaven and earth existed until today, all directions—nothing is unseen, nothing is unknown, nothing is unheard; one who obtains all wisdom may truly be called enlightened!

—Excerpted from The Sutra of Forty-Two Sections Spoken by the Buddha

From ancient times to the present, humankind has had an intense thirst for knowledge, hoping to understand the universe and the questions about our body and spirit, and to reach states of "freedom from illness," "freedom from confusion," and "freedom from vexation." From "before heaven and earth existed" to "until today," and even into the future, we are curious about everything. The Buddha said only one who "knows everything, has heard everything, and obtains all wisdom" about all things past and present may "truly be called enlightened." But such people are rare; the vast majority have all kinds of cognitive blind spots and cling stubbornly to their own views. That is why our world is endlessly embroiled in strife, and why so many people live in all kinds of suffering.

From a biological standpoint, life on this planet has evolved for four billion years. Roughly, life is made of three chemical elements—hydrogen, carbon, and oxygen—and 98% of living organisms consist of these three atoms. Genetic differences between animals are not large: we share 98% of our genes with chimpanzees, 97% with gorillas, and 87% with zebrafish, a common laboratory animal.

The body we regard as so precious does not in fact fully belong to us. Over a thousand kinds of viruses parasitize our bodies, along with vast numbers of other microorganisms, such as various bacteria. A considerable portion of the nutrition and calories we draw from food supports those invisible microbes inside us. Of course these microbes also contribute to us: they help us break down food and solve many other problems.

At least 35% of the genes in our genome are useless; apart from consuming calories, they serve no purpose. If we could clear out these useless genes from birth, our bodies would be healthier and we would live longer. We would not need to consume so much food, nor to toil so hard to make a living.

Why is the human genome so complex? Because we have traveled so far down the road of evolution that a great many things have been integrated into our genome. We have always been locked in antagonism with pathogens and other organisms: germs invade our bodies, our bodies develop corresponding countermeasures to fight them, in this struggle the victors survive and the losers are eliminated, and the victors' genomes gain new members produced in the struggle against disease.

In this way nature selects those adapted to the environment, enabling them to reproduce; the offspring of these lucky ones inherit their ancestors' genes. These genes have both beneficial and harmful sides.

For example, genes closely associated with sickle-cell anemia and thalassemia arose in response to malaria. This means the ancestors of patients with these inherited diseases once had malaria and fortunately survived; humans have at least twelve genes conferring hereditary resistance to malaria. The ancestors of osteoporosis patients may have been lucky survivors of tuberculosis; their vitamin D receptor genes were altered. People of different blood types also differ in susceptibility to cholera and malaria: type O is more prone to cholera, yet seems to resist malaria better than other types and may also be less prone to cancer. The genes that determine our blood type are likewise involved in defense against disease.

Over the past four billion years, we evolved from extremely unstable RNA through trial and error into DNA, and from DNA into organisms of ever more complex molecular structure. Our remote ancestor may have been a thermophile; this "Last Universal Common Ancestor," named Luca by biologists, perhaps still lives deep underground in cracks of hot igneous rock.

From the day Earth was born four billion years ago, chemical reactions on the planet have never ceased. Life is merely one of many chemical reactions. What exactly occurred in nature as the simplest life forms evolved into higher intelligent animals such as humans is something humankind keeps exploring, with no final conclusion to this day.

We wish to reproduce; the various microbes parasitizing us also wish to reproduce. The underlying reason is that every gene has a powerful drive to replicate itself. Our flesh is the living space and battlefield of 20,000–25,000 genes; different genes compete and cooperate within us, and each gene is essentially selfish—it wants nothing but to keep copying itself.

But when different genes replicate within the same body, conflict inevitably arises. Cancer cells born of certain mutated genes, for example, want to replicate infinitely, which restricts the living space of other genes. So our genome, to maintain an internal ecological balance, produces a series of mechanisms to resist the unrestrained self-replication of certain harmful cells. The most common approach is to methylate the DNA of those infinitely replicating cells or to generate new antagonistic genes, thereby controlling the overexpression of certain genes.

The most fundamental known element of life is the gene; each gene has its own evolutionary history, and human evolution is essentially the evolution of the human genome. Just as we humans keep evolving, other organisms and microbes also keep evolving, and they have their own genomes. Moreover, those microbes evolve faster than behemoths like us: the number of generations we take tens of millions of years to complete, viruses and bacteria accomplish in mere decades.

When we use antibiotics against bacteria, the bacteria strive to evolve drug-resistance genes; when we use anticancer drugs against cancer cells, the cancer cells evolve new genes that can counter the drugs. In nature and in the human body, such antagonistic relationships are everywhere. Precisely because of them, life grows ever more complex, the contents of the human genome ever richer, and human intelligence ever higher.

This is life in the biological sense: a gene-driven, continuously evolving series of biochemical reactions under various internal and external conditions. It explains why the world contains such a rich variety of species, where many diseases come from, and many phenomena we previously could not understand. Biologists like to regard the discovery of genes as a highlight of human wisdom and one of the greatest scientific discoveries in history.

From this perspective we see that the essence of life is a set of chemical reactions. But when I decided to study biology and, not understanding many concepts, asked my middle-school son for help, we also had some debates.

For example, I asked him: if life is purely a chemical reaction, then thought and emotion are also chemical reactions, and the same chemical reaction should yield the same result. Why do different people think differently about the same thing? Why does the same event provoke different emotional responses in different people? My son said it was meaningless for me to bring a philosophical question into the domain of biology. I also asked a biology PhD; he could not explain it clearly either and could only fob me off with remarks like neurology being the most complex thing of all.

Life is wonderful, and everyone experiences and focuses on it differently. For instance, while I read biology, genetics, and medical books with relish, my wife sits beside me laughing loudly at Guo Degang's crosstalk. To her, headache-inducing terms like genes, the DNA double helix, chromosomes, and methylation are far less interesting than good food and films. Occasionally she leans over to see what book her husband is reading, reads a few lines, and cannot go on.

She may never do much research or thinking about the life sciences, yet she will live as happily as I do, or more so. I often study and ponder the questions of life; while I may thereby uncover its mysteries, I may also go astray, lose interest in ordinary life, and fall into a nihilistic trap induced by science. Some biologists in history have indeed been melancholy—Paul Hermann Mller, the 1948 Nobel laureate in Physiology or Medicine, is said to have sunk into deep depression.

Fortunately my understanding of life is pluralistic. While reading biology and modern medicine, I also read TCM classics, classical literature and philosophy, and even religious works. In each kind of writing we find a different interpretation of life.

And when I fall ill, I do not cling to any one doctrine; I simply use the most convenient method to solve the problem. For example, a few days ago I rode outdoors thinly dressed, caught a bit of wind-cold, and woke the next morning dizzy and spinning, nauseated and wanting to vomit, with diarrhea; I knew I was ill.

Should I explain this with biochemical reactions? With TCM theory? With plain common sense? Or should I panic and worry I had caught COVID-19?

In fact, in that deeply uncomfortable state I thought about nothing; I just had my son brew me two packets of Gegen Tang (Pueraria Decoction) granules, drank them, then turned on a hair dryer and blasted my neck. Once I broke into a sweat, I covered my head and slept. After an hour or so I woke needing to urinate; getting up to go to the toilet, I found I had recovered.

I simply followed, out of habit, the TCM principle of "treat heat with cold and cold with heat": having contracted wind-cold, I used medicines and methods that expel wind-cold to solve the immediate problem, without being bound to any fixed method.

The illness may indeed have arisen because I was thinly dressed and caught cold, or because I picked up some pathogen outdoors, setting off certain biochemical reactions in my body. And in this crude, swallowed-whole treatment, did other chemical reactions occur that returned my body to normal?

If one insists on explaining it deeply, it may be something like that. But to express this process of falling ill and recovering precisely in chemical equations, few people in the world besides me—perhaps no one—would be capable. The complexity of even such a simple illness and cure far exceeds what textbook knowledge can handle.

Human ability is very limited; we have only a limited understanding of life and disease. Many genes in our genome act in concert rather than singly, which makes the problem extraordinarily complex. We will continue to evolve on this planet, and the pathogens around us will continue along that evolutionary highway. I used to think that one day we might solve all disease problems; now I know that is impossible.

After we solve old diseases, new ones arise; and whether we treat disease with our own immune system or with drugs, unpredictable side effects are possible—for example, the thalassemia and osteoporosis mentioned above are side effects produced when our immune system fought malaria and tuberculosis. Likewise, when we invent a drug to treat a disease, the causative pathogen keeps evolving into more virulent offspring. As long as we live in nature, new pathogens will attack us as we interact with it, and new elements will join our genome.

I have gradually realized that my earlier rejection of fatalism was not entirely correct. Some diseases, such as Huntington's disease, are caused solely by genes and have nothing to do with other factors. For such a disease, falling ill is a kind of fate: either you carry the Huntington mutation and will get it, or you do not and will not. No matter how well a person knows how to preserve health, if his family carries this mutation and he carries it himself, he will develop the disease at a certain age.

So for such fellow human beings, we can only deeply sympathize with their misfortune. And those of us who can live relatively healthily and easily must humbly recognize that much of our good fortune is a gift from heaven. Heaven has bestowed more blessing on us, not because we are superior to those who have suffered misfortune, making us healthier and smarter.