What on Earth is Life？
Wu Zhi
What is life? A good many people offer many answers to it; however, to find out the genuine definition of life is not an easy job. As a matter of fact, human beings follow the course from easy stages to difficult ones and then to complicated ones in quest of the cognition of life, so there appear different versions of interpretations for the definition of life, arrived at by different people from the different perspectives, which may stand to reason in a sense. They only reflect a certain profile, a certain feature of life, yet none of them genuinely discloses the true essence of life.
What's the difference between a living man and a dead man? They have no difference viewed from the perspective of substance because substances in a living human body also exist in a dead human body and these substances are identically arranged. However, the greatest difference between a living man and a dead man lies in that a living man can move while a dead man can not anyhow. A living man has the inner activities and the external activities which in essence is the very expressive form of the inner activities.
As it is, life is not a certain substance but a certain activity. Life takes three different forms of activities, respectively physiological activity, psychological activity and physical activity. And the controlling center of the three movements is the human brain, thus engendering the illusion that life exists in the human brain. The three different movements of life, in the final analysis, should be attributed to the chemical movement.
The chemical movement represents the movement of changes of inner space and structure of the substances. Thus substances defined here refer to particles and their organic combinations body. All substances smaller than atoms are collectively called “particles” but not “elementary particles” because a elementary particle are not an elementary unit and can be further segmented into smaller particles. According to this definition, substances can be arranged in the following sequence:
Particle — Atom — Molecule — Macromolecule — molecular group — big molecular group — huge molecular group
Human, elephant, whale and tree are all organic combinations body, belonging to the category of the substance, and can be deemed as the huge molecular group. Whereas, iceberg and ocean, simply piled up by ice and water, can be deemed as objects. As a matter of course, it is not a blunder in a sense if they are deemed as a group of substances, but here we don't take them as substances for the time being.
If a substance undergoes a change process from small to large, it is also called “polymerization process”；on the very contrary, if a substance changes from large into small, it is called “Decomposition Process”. These two processes are actually the chemical movement, also called “Chemical Reaction”（Note: this definition is a little broader than the general definition in terms of the denotation）. The chemical reaction hereby represents a process where one kind (category) of substance increases while the other kind (category) of substance decreases.
Development of life consists of two separate processes, respectively polymerization process featuring the change of substances from small to large and the decomposition process featuring the change of substances from large to small. If polymerization is larger than decomposition, the individual substance becomes gradually enlarged; if decomposition is larger than polymerization, the individual substance becomes gradually diminished; if polymerization is equal to decomposition, the individual substance will remain unchanged. Anyhow, polymerization and decomposition are both the processes of chemical reaction.
By this token, life is a kind of chemical reaction or a process of chemical reaction and a form of chemical reaction, so life and chemical reaction are congruent. A living man has life mainly because there is chemical reaction within his body while a dead man has no life mainly because there is no chemical reaction in his body (to be specific, there are only weak another kinds of chemical reactions). Human is just a mass of substance under chemical reaction and also a mass of substance under sustainable combustion. The carbohydrate, fat and protein in the human body are in constant combustion and the carbon in these substances is taken away by oxygen and produces carbon dioxide which is discharged out of the body. “Light” and heat is released in the combustion process and the so-called light is also the infrared ray, but it is a kind of a slow combustion process, so we might as well name it as subcombustion. If we refuse to admit that burning of the wood is life, the burning within the human body will neither be deemed as life. If so, the human life is water without a source, and a tree without roots. When the combustion process ceases within the human body, human life will be gone. This demonstrates that combustion is life and life is combustion. That is to say, chemical reaction is life and life is also chemical reaction.
A human being can either senses the existence of his life or cannot sense it, but everything depends on whether a human being has a brain with a sound sensory function. There exists life in the human vegetable but he or she can not sense the existence of life; everything in the universe there is life, however, the majority of lives do not sense the existence of their life. A stone, a car and a celestial body have their own life; they don't sense the existence of their life, though. Nevertheless, the objective existence never depends on the subjective sense. Even a normal man does not sense the existence of his life while he is sound asleep. In all conscience, sense of life is relative and it is not absolutely true that when we think there is no sense inside life body. Even if there is no brain, there is still faint sense. In view of the current knowledge of human beings, cells don't have a brain, however, a cell has a sense of the external stimulus and surely a cerebral cell shows stronger sense of the external stimulus. Or otherwise, the brain cells can not assemble many weak senses and gradually enlarge them. As a consequence, we can give a more essential definition of life: life, in a broader sense, refers to all chemical reactions; while life, in a narrower sense, refers to the orderly combined and intricate chemical reactions.
What is orderly combination and intricate complexity? As a matter of fact, it refers to all types, all scales and all strata of chemical reactions and the chain reaction as per a certain rhythm and sequence. Human is the substance, carrier, stove and reactor of chemical reactions. The combustion within the human body and the burning of wood are both the process of chemical reaction and also an expressive form of life, however, the former is a life process in a narrower sense while the latter is a life process in a broader sense. In the eyes of astronomers, the sun is alive while the moon is dead, which is not only a literal description and a metaphor but also well-founded because there are chemical reactions in the sun but there is not chemical reactions in the moon (comparatively). The earth is also a life body，but it is a lower form of life because the basic and main chemical reactions of the earth take place in the earth core and the reactivity of the chemical reactions are lower than the chemical reactions on the sun, yet higher than chemical reactions on the moon. As for the different levels of life, we can sum them up as follows:
Animals, plants and microorganisms are advanced life. The more types and more extended combinations chemical reactions take, the more complex and advanced forms life takes. Therefore, living things can be further demarcated in terms of the life classification, and human beings had also categorized living things into lower animals and higher animals etc. Of course human life is the most advanced life form because each cell in the human body is a reactor which can conduct many different chemical reactions. There are many different chemical reactions with various scales taking place simultaneously or by turns within human body. As far as the number of chemical reactions is concerned, it comes near to an astronomical figure; in terms of types of chemical reactions, the number is too numerous to enumerate; and there are more than 2,000 catalysts (enzymes), which correspond to at least 2,000 or more chemical reactions because more chemical reactions are not likely to depend on any catalysts. Nevertheless, how large the number is remains to be studied by human beings. Viewed only from known situations, chemical reactions in the human body represents the most complexity in the universe, so human is the most complicated substance and the most advanced life-form in the universe, it's the case at least judging from knowledge of mankind. As a matter of course, the human body can be, as a whole, regarded as a chemical reactor which can take in gas, liquid and solid and get them mixed for the chemical reactions, producing gas, liquid and solid, which are then discharged out of the human body. And the other substances within the human body also participate in the chemical reactions.
Chemical reactions have two important characteristics: one is inertial motion. Once a reaction takes place, an immense force will thrust it until the chemical reaction is thoroughly conducted unless another more immense force puts the brakes on it. This kind of thrusting force is can called as “Chemical Thrust” while this kind of resisting force can be called as “chemical resistance”. The other is the chain occurrence. A chemical reaction can trigger off a cluster of chemical reactions. When one point is affected, the rest will be affected correspondingly, similar to the domino effect. Just because the two characteristics exist, life can be generated and extended, or otherwise there will be no life in a narrow sense. The ovum is activated by the catalyst (enzyme) taken by the sperm and the chemical reactions take place in a dynamic way. So a chemical reaction triggers off ten, hundred, thousand, ten thousand and incalculability chemical reactions until a human being breathes his last. The oxidation reaction is the most common forms of chemical reactions within the human body; when food and oxygen is taken into the body, the oxidation reaction just occurs in turn, ultimately producing water and carbon dioxide etc., which as wastes shall then be discharged out of the human body, so the human body obtains the energy from the chemical reactions.
There are three commonly-seen inducing factors enabling the chemical reactions within the human body: one is triggered off by relevant chemical reactions; the second is directly triggered off by external substances and the third is triggered off by the secretion of the enzyme inside the human body. Many psychological activities and physiological activities are triggered by the secretion of the enzyme. Occurrence of emotions and desires particularly tend to rely on the secretion of enzyme. In the course of the body development and reproduction, human body is also subject to stimulation of all kinds of enzymes. So it follows that enzyme exerts a catalytic action in the chemical reactions within the human body. As a matter of fact it is a kind of catalyst, but human beings still have a smattering of knowledge of enzyme.
The physical movement, physiological movement and psychological movement of life can be either referred to as “Chemical movement” or as the expressive form of chemical movement.
Physical movements of the human such as running and jumping are expressive forms of chemical movements, and the direction and force of the human body movement are the very results of the chemical reactions in different parts and with the different intensity. The explosive chemical reaction should get the explosive force while slow chemical reaction should have a lasting force. All actions including physical movements within the human body are expressive forms of chemical reactions: chemical reactions of the brain evoke chemical reactions of the muscles.
The human physiological movement is also a kind of chemical movement, and the cellular movement, tissue movement and organic movement are entirely the movement among chemical reactions. The blood circulation and the bioelectricity belong to the category of physical movement but they are the derivative movement or accessory movement of the chemical movement. The chemical reactions of heart cells cause the heart to pulse and promote the blood circulation. The blood movement is a kind of material flow, namely the surrounding substances that participate in the chemical reactions flow into the stoves of the chemical reaction--- all cells of the human body and the blood flow comes from the chemical reaction and serves the chemical reaction, so this kind of physical movement is derived and affiliated to the chemical reaction. Chemical reaction at the nerve terminal makes nerve of the conductor lose electrons which freely float in the nerve; meanwhile, chemical reaction take place at another terminal, which need electrons, so pushing the electrons at one end and dragging the electrons at another end induce electrons to move in the nerves, thus forming the electric current. This kind of physical movement is completely an expressive form of the chemical movement, constituting a part of the chemical movement. Certainly, the electric current in the nerves is a very important part to the formation of life, playing a vital role as a bridge linking up chemical reactions and this bridge makes it possible that the chain chemical reactions take place.
Human psychological movements are inexplicable movements for human beings, but when they are matched with corresponding chemical reactions, the mysterious intricate untraceable psychological activities will expose themselves in their true colors. Sensation: the chemical reactions of sensory organs evoke the chemical reactions of the corresponding zones of the brain. Memorization: the chemical reaction of the past experiences is repeated. Emotion: Stimulated by some substances or information from either external or interior of the body, certain chemical reactions occur or change. Desire: when normal chemical reaction is subject to interference or the chain chemical reactions are impeded, a kind of driving chemical reaction is thus evoked.
The life process is a sustained process of chemical reaction, so life is terminated with the end of the chemical reaction. All kinds of factors can contribute to the termination of life because chemical reactions follow a tightly-linked circle one after another. So if one link is damaged in the chemical reaction, the whole reaction will cease, terminating the life that way. It is too many life links that accounts for the vulnerability of life as one of the reasons.
On balance, everything related to a human being has something to do with the chemical reaction and only chemical reaction can unveil the mystery of life. Life is the continuation of chemical reactions; death is the cessation of chemical reactions; ageing is slowdown of chemical reactions and disease is disorder of chemical reactions. There are thousands upon thousands of diseases tormenting human beings, the majority of which are difficult to eradicate in that there is a great variety of chemical reactions within the human body and human beings have not figured out what kind of chemical reaction disorders generate the diseases. Compared with the chemical diseases, physical diseases are easily visible and tractable. A broken leg or arm can be transplanted while a clogged coronary artery can be dredged by building a new bridge.
Any kind of disease can be explicitly explained by chemical reaction; any kind of therapy can also be explained by chemical reaction, and so can any kind of food. For example, human beings only know the importance of Vitamin but don't know why. Vitamin actually is a kind of catalyst or its auxiliary molecule playing the role of a catalyst, accelerating certain kinds of chemical reactions within the human body. Medicines and injections just transmit the raw materials or catalysts to the human body for chemical reaction, so the chemical reactions within the pathogens are destroyed and maintain the chemical reactions beneficial to the human body.
Conclusion: Since only chemical reaction can account for life, life is in essence a chemical reaction. In the final analysis, life is only represented by some chemical reactions and the life body is a block of substances under chemical reactions. Substances aggregate and chemical reactions occur in turn, so the substances aggregation constitutes the life body. Advanced life is only a more complex form of chemical reaction more closely related with each other and lasting a much longer period of time. As it is, advanced life is in essence an aggregation of substances with physical and chemical properties and without ultimate distinction from other substances.
Since life is a chemical reaction, the research objective of Life Sciences is clear-cut. Fundamentally speaking, Life Sciences are the research and study of the chemical reactions of the life body. Let's put it more specifically, firstly, try to find out all chemical substances in the life body, particularly all kinds of chemical compositions in the cells. Secondly, try to find out all chemical reactions of the life body, particularly all kinds of chemical reactions within the cells, including the reactants, catalysts and resultants, and find out all chemical mechanisms related to the cellular evolution and biologic evolution. Thirdly, try to find out all relationships among chemical reactions within the life body, including how they relate, their sequential arrangement, causes and effects, scale, priority and length etc; Fourthly, try to find out all information and information carriers of the life body, that is to say, decipher the life languages including gene language, communicative language, control language (control activities and control life and death) etc. Categorized by the language carrier, it can be divided into chemical language and physical language, say, bioelectricity etc. Fifthly, try to find out all relationships between life and the environment including how they interact with each other. Certainly, Life Sciences should also include other research contents.
On the whole, Life Sciences focuses on the study of deep and essential things of the life body, namely exploring the mystery of life, representing the study of the molecule strata and fundamentally a microscopic science; Bioscience is mainly oriented toward the study of the superficial and intuitional things of life body, namely the study of the body, the individual, the group, the community and the collectivity of living things, certainly including the inner conformation and working principle of the organism, fundamentally representing a macroscopic science. Put it simply, Life Sciences studies “shebang” while Bioscience studies “objects”; Life Sciences studies “small things” while Bioscience studies “large things”. Although shebang and objects, small and large are not inseparable in terms of magnitude, yet their key point and purpose are quite different. Surely, the two sciences are partially overlapping as interdisciplinary sciences, but the study of the essence can not divorce from superficial representation; the study of microscopic view is heavily reliant on macroscopic and the study of part is inseparable from the entirety.
As far as the present human knowledge is concerned, we can only explain life to the stratum of chemical reaction. With rapid development of human sciences and enrichment of knowledge, in-depth exploration of the essence of life shall be tremendously enhanced. For example, the essence of the chemical reactions can be explained: the essence of chemical reaction is the expressive form of energy, which is the most active element in the universe and is in constant change. And the change of energy is represented by substance. So in a sense, substance is only the external shell of life and energy is actually the essence of life. This kind of exploration is never-ending because substance is changing indefinitely, so is energy. And science is eternally inexhaustible.
No reference. All arguments presented herein are based upon the college textbooks and popular science readings, which is an integral part of the human knowledge, so this author does not cite the research results or findings of any other scholars, including their personal ideas or arguments. In addition, no reference is because many arguments from my own body and the environment around.
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