Abstract  Even the chemical component of the first life was found, it would not be the essence of life. This gap in understanding is not only a technological neglect, but also an absence of a main concept — positive feedback. All the existent definitions of life have obvious faults, including the Theory of Life as Metabolism, Supple Adaptation, Information and the Heredity. Modern system theories, including the Dissipative Structure Theory and the Hypercycle Theory, have not provided a precise definition of life, either. Self-reproduction is the essential characteristic which is owned by all creatures and not by all non-living things. The premise of evolution of creatures is the survival of their complex structures. The reason of the survival of complex structures is the index increasing of the number of creatures. The reason of index increasing is self-reproduction. Self-reproduction can solve the probability problem of the emerge of complex structure. The definition of life: Life is a kind of relatively steady and complex system with special structure, the structure enables it to have the function of making its structure survive in nature by self- reproduction. The ability to make its complex structure survive by its own properties is vitality. Research of artificial life inspires us that it is possible for life to exist without material like carbon, hydrogen and oxygen.

Keywords  Philosophy of science and technology, origin of life, system science, self-reproduction, positive feed- back

Ⅰ. The Essence of Life and a Main Concept

The origin of life is not only a scientific problem, but also a philosophical problem. It is one of the four origin problems which should be answered in the 21^st century. Although scientists have been able to obtain all genetic maps of human being and other creatures, this is not enough to really understand life. It is knowing hows but not the whys. Most scientists still research the origin of life from chemical component, especially complex organics with carbon. Even the chemical component of the first life was found, it would not be the essence of life. After a chemical way of the origin of life have been found, the second, third and forth ways should be searched continually. The generality of these ways is the essence of life. This gap in understanding is not only a technological neglect, but also an absence of a main concept, this concept is positive feedback.

Ⅱ. Disadvantages of Existent Definitions of Life

The definition of life is related with the origin of life, both of which rely on the the understanding of life. At present, there are two kinds of definitions of life, one is the Definition by Function, which defines life by its properties and functions, and the other is the Structural Definition (or the Entity Definition), which defines life by special structure of life. There are two kinds of the Definition by Function, one is the Cluster Definition which regards life as an assemblage of many properties, and the other is the Root Property Definition, which consider one or a few properties as the essential property of life (Li, 2002, p.24-39). All of these definitions have obvious disadvantages.

Disadvantages of Four Root Property Definitions

Four Root Property Definitions are the Theories of Life as Metabolism, Supple Adaptation, Information and the Here- dity.

The Theory of Life as Metabolism. The Theory of Life as Metabolism considers the continuous process of meta- bolism of material and energy as the basic property of life. Erwin Schrödinger developed the Theory of Life as Metabolism and created the theory of negative entropy in his book What Is Life, “Thus a living organism continually increases its entropy.” “It can only keep aloof from it, i.e. alive, by continually drawing from its environment negative entropy” (Schrödinger, 1992). This opinion is continued by the Theory of Dissipative Structure.

These theories are not right. Although every kind of life is a self-organizational system and a dissipative structure, not all self-organizational systems and dissipative structures are lives. Some non-living things, like laser and internal combustion engine, are capable of self-organization, drawing negative entropy and dissi- pating it, too. So self-organization, drawing negative entropy and dissipation are not sufficient conditions of life.

The essential property of life must be possessed by all creatures, and must not be possessed by any non-living things. If the requirement is relaxed, we can list many properties of life to fit. For example, each life must be matter, and what is not matter is not life obviously.

The Theory of Life as Supple Adaptation. The Theory of Life as Supple Adaptation is provided by Mark A. Bedau at the Reed College in America. He supposed the definition of life as following：

“X is living iff

“X is a supplely adapting system, or

“X is explained in a right way by a supplely adapting system” (Bedau, 1998).

The standard in this theory to decide if a system is supplely adapting or not is not clear. Many non-living things are able to change variously, like river, cloud and sand hill. They can also be regarded as supple adaptation. It is not clear, either, that whether dead creatures and extinct creatures are supplely adapting systems.

What is more, the ability to supplely adapt is a result instead of reason. The ability of supple adaptation of life mainly comes from its enormously complex structure. It will be explained in this article that inheritance is the sufficient and necessary condition for life to maintain the complex structure. Breeding, therefore, is the sufficient and necessary condition of the ability of supple adaptation. Bedau did not point out the relation between breeding and supple adaptation.

The Theory of Life as Information. Jianhui Li claimed that the Theory of Life as Information pay attention to the delivery of information in the process of growth and breeding of life. An entity is life if it has the ability of self-reproduction or breeding in style of Von Neumann(Li, 2002, p37). This definition is right if the word “delivery of information” means self-reproduction or breeding. But Jianhui Li did not emphasize the special way of the delivery of information in life. Nor did he criticize teleology by the theory of breeding.

A lot of non-lives are able to deliver information. So the ability to deliver information is not the main standard to identify life. It is right to say that the essential property of life is information or delivery of information, but it is not right to say that the essential property of non-life is not information or delivery information. Only those who can deliver all structure information of themselves are life. Computers can deliver information, but most of these information have nothing to do with their own structure, or are not all structure information of themselves.

The Theory of Life as Heredity. J. Maynard Smith said, “entities are alive if they have the properties of multiplication, variation and heredity” (Smith, & Szathmáry, 1997). While the definition of J. Maynard Smith had, in fact, made major answer clear, it has a few dis- advantages. First, multiplication is the same as heredity in terms of the essence of life, they can not be put side by side. Second, variation is not a characteristic exclusively owned by life. What is more, J. Maynard Smith said, the definition of his own “is inadequate if we want to understand the origin of life.” “To explain the origin of life requires that we explain the origin of metabolism as well as of replication” (Smith, & Szathmáry, 1997). But he did not provide a definition of life to explain the origin of metabolism and replication.

Cluster Definition of Life

Some definitions of life were made by listing a series of characteristics of life. It is clear that among the characteristics, many are not general and necessary conditions of the origin of life. This kind of definition brings a puzzle that whether a system is life if it has only some of characteristics in the assemblage. For example, growth and cellular differentiation are the characteristic owned exclusively by life, but not all lives. Virus and protozoa do not have these characteristics.

The list of Mayr is the most influential:

l All levels of living systems have an enormously complex and adaptive organization.

l Living organisms are composed of a chemically unique set of macromolecules.

l The important phenomena in living systems are predominantly qualitative, not quantitative.

l All levels of living systems consist of highly variable groups of unique individuals.

l All organisms possess historically evolved genetic programs which enable them to engage in teleonomic processes and activities.

l Classes of living organisms are defined by historical connection and common descent.

l Organisms are the product of natural selection.

l Living processes are especially unpredictable (Bedau, 1998; Mayr, 1982).

Some of these characteristics are phenomena instead of essence, some are not special characteristics of life.

l The reason why living processes are especially unpredictable is the complex structure of life. The reason why life can maintain complex structure is the breeding of life.

l Historical connection is due to breeding, too.

l Non-living things can also be unique, variable and being product of natural selection, these characteristics are not owned exclusively by life.

l The ability of evolution comes from inheritance and variation. Inheritance is the essential property of life, but variation is not essential property of life. There is no difference between variation of non-life and that of life, maybe except their names.

l It only proves how complex life is that the important phenomena in living systems are predominantly qualitative, not quantitative. Research of quantitative of life, however, is increasing rapidly by the development of science.

In conclusion, the Cluster Definition of life is not able to separate life from non-life. Sometimes, it is said some non-life are vital like flame, river or the Earth, just because they have some of upper characteristics.

Structural Definition of Life and Molecular Biology

Friedrich Von Engels said, “Life is the existing status of proteins. The essence of the existing status is the continual reconstruction of chemical component of these proteins by themselves” (Marx, & Engels, 1994).

After 1950s, this view changed by the discovery of double helix of DNA and its inheritance. Nucleic acid which is able to reproduce itself and carry hereditary information began to be treated as the molecular basis of life.

At the beginning, molecular biology was expected to help us to discover the essence of life. During a long period after the revolution of molecular biology, however, most philosophers and biologists seemed to have forgotten the question of the essence of life. Why?

The major method of molecular biology is reductionism aiming at component. This method was successful in finding the essence of matter. Material consist of molecule, molecule consist of atom. This reductionism have found generality of all material which is a few kinds of components and their simple combination.

The generality of life is special ways of combination of positive feedback and negative feedback, which determine the characteristics of life. The generality of life have nothing to do with components. Molecular biologists, therefore, cannot find the generality of life by reducing simply to components like physicists. What is more, molecular biology is not able to tell whether chemical ways are necessary conditions of the origin of life.

Ⅲ. Progress of System Theories

System theories pay attention to structure of system instead of components. So it is not surprised that system theories plays important role in research of life. The starting point of system theories is the belief that function is determined by structure. The reason why life has different characteristics with non-life is that life has different structure.

Early system theories was not influential because they did not find relations of feedback. Later, negative feedback was discovered. As a result, the Cybernetics progressed quickly. After that, the Dissipative Structure Theory and the Hypercycle Theory discovered some phenomena about positive feedback, so they won the Nobel Prizes.

System theories have not provided a correct answer of the essence of life yet. The Dissipative Structure Theory noticed that order and self-organization are possible when system is in the state of non-equilibrium by consuming energy (Prigogine, Nicolis, & Babloyantz, 1974). But it did not notice that neither the state of non-equilibrium nor consuming energy is necessary conditions or sufficient conditions of order, let alone necessary and sufficient conditions of life.

The Dissipative Structure Theory takes openness, nonlinear and fluctuation as the essence of self- organization. But they are not important though they are necessary conditions of self-organization. At least they are not essence of life. Because openness, nonlinear and fluctuation are not special characteristics of self- organizational systems, let alone special charac- teristics of life. There is not any closed objective system in the world. There are fluctuations everywhere. There are many kinds of nonlinear processes. As a kind of nonlinear process, sine wave has nothing to do with self- organization.

Zheng Weiming said, “Breeding is a promoting power by which creature manages to survive and develop, it is a kind of positive feedback.” “Autopoieses, autocatalysis, self- organization and so on are all positive feedback which is the reason to promote systems evolving ” (Zheng, 1998). But he did not explain whether the origin of life is the result of positive feedback, nor did he provide a definition of life.

The Hypercycle Theory by Manfred Eigen (Eigen, & Schuster, 1979) was a breakthrough of life science which has been regarded as a classical theory. But Eigen did not provide a definition of life. Nor did Eigen noticed that Hypercycle is not the sufficient condition of life origin. For example, a system with tricarboxylic acid cycle is perhaps not a life.

Hu Hao demonstrated the mechanism of self-organization, “Positive feedback like the triple molecule model (2X+Y=3X), make system create effect of cooperation on quality and amplification effect on quantity. Because of this kind of interaction chains in which reasons are also results, a fluctuation used to be in a limit scope is possible to be amplified to the whole extent during a short period, and become a new orderly structure. Interactions of this kind of positive feedback is the micro-mechanism of system evolution in subsystem level” (Hu, 2002). Hu Hao explained the most important mechanism of self- organization clearly, but he did not use this micro- mechanism to explain the origin of life.

The book of Erich Jantsch The Self-organizing Universe analyses deeply the effect of positive feedback. But as the same mistakes of I. Prigogine, instead of treating auto-catalysis or self-reproduction as the essence of self-organization, Jantsch regarded non-equilibrium and metabolism as the essence of self-organization, and regarded fluctuation and openness as the essence of realizing order (Jantsch, 1980, p.55). He did not regard self-reproduction as the sufficient condition of the origin of life (Jantsch, 1980, p.103). What is more, Jantsch had some wrong concepts in his book. For example, he criticized reductionism (Jantsch, 1980, p.3), and said, “Autopoietic system is characterized by a certain autonomy vis-à-vis the environment which may be understood as a primitive form of consciousness corresponding to the level of existence of the system” (Jantsch, 1980, p.15-16). Nor did Jantsch provide a precise definition of life. So the book became less influential than it ought to be.

Ⅳ. Probability of Super Orderly Structure

of Living System

In 2010, an article on Science noted that a kind of bacterium called “GFAJ-1” in mono lake seems to be able to synthesize DNA and other molecules using arsenic instead of phosphorus, which has not been heard in other creatures (Simon, 2011).

This, however, is not strange, because the essence of life is structure instead of element. Life can not only be created on the basis of Carbon, Phosphorus and Arsenic, but also on the basis of Silicon. Artificial intelligence will become life if it is capable of self-reproduction.

The structure of life is the same as or more important than properties, for the complex structure is the sufficient condition of order and all kind of life properties. So the only puzzle of life is that why complex structure is possible to survive during billions of years.

Complex structure is difficult to emerge and easy to be destroyed. Creature is normally made of material of macromolecule, most structure of which are especially complex. Structure of non-living things is much simpler than that of living things in nature, because complex non-living things are not capable of self-reproduction.

All kinds of non-living things are continuously emerging and breaking. Some non-living things are always emerging with large quantity, like ice and rust. Some non-living things are difficult to be destroyed, like sands and noble gases. So these things are easy for us to find. There are, however, many non-living things which is slow to emerge and rapid to disappear, for instance, metal like natrium and kalium will be oxidized rapidly in the air. So these things are difficult to find in nature.

Theorem: Material of any structure can exist for a long period only when the speed of generation of its structure is faster or equal to the speed of its breaking.

This seems to be nonsense, but it is very important in fact. Darwin did not make the meaning of the word fittest clear because he did not find this theorem.

Ever existent kinds of non-living structure must be much more than that is now existent, including something much more complex. But complex non-living things are slow to generate and fast to break. So there is not any of them now. The more complex their structures are, the more difficultly they generate and the more easily they break. So there is no non-living thing which is as complex as living things are.

Why are living things so complicated then? Senior creatures have properties which make their structure steady like regeneration and immunization, while many other creatures have not. How do other creatures make their structure exist continuously with large quantity?

Friedrich Cramer studied life science together with system theory, he asked the same question in his book Chaos and Order. He believed that high degree of order in living systems is an extremely improbable state.

DNA consists of four kinds of nucleotides. Each nucleotide has different base pair. If four letters A, B, C and D are ranked, there are 24 sequences: ABCD, ABDC, ACBD ……. There are large quantity of nucleotides in human DNA, and there are colossal sequences, while only one of them is correct. If it is wrong, man will be ill or die.

Scientists have learned the DNA blueprint, in particular the amount of genetic information and molecular structure of bacterium Escherichia coli (E.coli). It is possible to calculate the number of ways these genetic plans might have been arranged in the blueprint and thus how many different ways the bacterial cell could have been constructed. The real molecule structure of bacterium E.coli is only one of these possibilities. For a E.coli, the probability of correct result by pure chance is one in 10^2400000. Even an intelligent machine could check these countless results at the rate of one per second, the time it costs would be far more than the universe age (10¹⁷sec) since the Big Bang. The universe age is infinitesimal compared with the time needed for the emergence of order by pure chance (F.Cramer, 1993, p.14). So Cramer believes that it is impossible for real molecule structure of bacterium coli to emerge by pure chance. Life could not have arisen by a series of random events.

There is a thought experiment of Monkey and Printer, which is also called as the Theorem of Infinite Monkey.If many monkeys play on many printers, they can finally get the works of Shakespeare. According to someone’s calculation, it may cost 200 billion years. If the order is produced in this way, it is impossible for us to exist.

Ⅴ. Why Creature Has Super Complex Structure

Cramer's conclusion leads to that only an infinite powerful immortal can raise the probability of life origin to realistic level. But this goes against the scientific spirit which began from Renaissance. How to solve this problem? The puzzle of life has always puzzled us in this way.

The faith in science means it is believed that life originated in a series of random events. Science has to explain why random events are able to give rise to life. There are two cases of that life originated in random events. One is extremely improbable, namely very lucky, not inevitable. If it plays again, life may not originate. Another is that life originated inevitably in a series of random events. No matter how many times it plays, life is able to emerge. Understanding life does not only need to explain why random events can make life, but also need to explain the inevitability of the origin of life.

Fortunately, one of the immortals is accepted by science who is called positive feedback. An old legend of India shows its power.

King Shirham wanted to reward his grand Prime Minister Sissa for inventing and presenting to him the game of chess. The desire of the clever minister seemed very modest.

“Majesty,” he said kneeling in front of the king, “give me a grain of wheat to put on the first square of this chessboard, and two grains to put on the second square, and four grains to put on the third, and so on, doubling the number for each succeeding square, give me enough grains to cover all 64 squares of the board.”
   “You did not ask for much, oh my faithful servant,” exclaimed the king. “Your wish will certainly be granted.” And he ordered a bag of wheat to be brought to the throne. But when the counting began, it soon became clear that with all the crop of Indian the king could not fulfill his promise to Sissa.
   To do so would have required:

18,446,744,073,709,551,615 grains!
   Assuming that a bushel of wheat contains about 5 million grains, one would need some 4×10¹² bushels to satisfy the demand of Sissa. Since the world production of wheat averages about 2×10⁹ bushels a year, the amount requested by the minister was that of the world's wheat production for the period of some two thousand years! (http:// www.rrting.com/English/othertm/57031/)

This is a kind of index increasing, i.e. a catastrophe or an emergency. The reason of this emergency is positive feedback. The more the number on an square of chessboard, the more the quantity to increase, the more the quantity to increase, the more the number on next square. So powerful the positive feedback is, that professor Cramer's puzzle could be easily solved.

New complex structures of non-living things and original creatures come from interaction between relatively simple materials or between simple material and environment. These interaction are random with low probability. But the probability of new complex structure is able to increase when the number of simple materials increases.

Each kind of creature, different from non-living things, is able to set up an index increasing of their body by breeding, which is a kind of positive feedback (with some certain environment). The more the basic quantity of a kind of creature is, the more the number to increase. The more the number to increase, the more the quantity of next generation is, just like the wheat. What is more, such processes have not only repeated for 64 times, but many billions of years. E. coli reproduces itself once per 20 minutes, in which rate it costs almost 304 years to reach 10^2400000. Man's cell divides once per 8-48 hours. If it is assumed 2 days, to reach 10^2400000 needs 44000 years, which is only a short instant in the evolution process.

What is self-reproduction? It is a special repro- duction.

Definition: If the motivity of reproduction is the function of the model and the process does not need any help from outside complex systems, this kind of reproduction is self-reproduction.

It should be noticed that self-reproduction does need helps from outside systems, which are simpler than itself, but does not need help from outside complex systems.

Self-reproduction formula of macromolecule is:

1 macromolecule + several micromolecules = 2 macromolecules

If more complex reproduction is considered, self- reproduction formula is:

Model + material = model + product (same as model)

There were only micromolecular non-living things and seldom macromolecular non-living things on the original earth before life originated. Once a kind of macromolecule got to have a simplest function of self-reproduction in nature, and it was quite steady in nature condition (breaking speed was quite slower than increasing speed), the number of this kind of structure would possibly increase as index curve to an overwhelming number which is called catastrophe. So this kind of structure would certainly exist steadily for a long period with large quantity. There had been always some of them survival within most kind of disaster. In this way, their special structure could exist continuously, namely their non- equilibrium structure could exist continuously, which means life had originated.

There are mistakes in self-reproduction, especially when the first life was RNA instead of DNA (Smith, & Szathmáry, 1997, p.37-39). But successful self- reproduction with a low speed is also possible to create index increasing, though it needs a long time, say, thousands or millions of years. Such a period of time, however, was only a second in the long river of evolution.

Because the natural selection and variation are always available everywhere, the continuous existing of macro- molecule was the most important condition for them to evolve continuously, which could certainly lead to a great variety of life. The main reason for life structure to exist continuously is the index increasing of its number, and the reason of index increasing is self-reproduction.

The death speeds of original life, which is same as non-living things, are determined by environment. The speed of emerge of non-living things is determined by environment while the speeds of creature generation can be increased by their own function. Self-reproduction of life cause index increasing, so the generating speed of life structure gets bigger than its death speed. Namely, the self-reproduction makes life adaptive to environment. Therefore, self-reproduction is sufficient condition of the origin of life.

The natural selection destroys systems with bad properties. The natural selection itself does not have any constructive function. So there could have been no life origin and evolution, if there was only natural selection without over-breeding. Variation of non-living thing can only affect a single body, the variation of life can affect a batch of bodies.

Ⅵ. The Sufficient and Necessary Conditions of

Life Origin and the Definition of Life

Theorem: The sufficient conditions of the origin of life is as following:

l A kind of material has relatively complex structure.

l It is able to self-reproduce in nature.

l This kind of structure is fit of some certain environment, i.e., it can make an index increasing of its number.

Anything which meets these conditions is life by all means, no matter whether it is constituted by protein or nuclear acid or other materials, no matter whether it transfers information for other life process, even no matter whether it is capable of metabolism.

Self-reproduction needs many conditions, maybe including certain materials, temperature, humidity, pressure, etc. But these conditions are not considered here in the sufficient conditions of the origin of life. If a system is able to self-reproduce, it has already had these conditions.

Self-reproduction includes simple self-reproduction and self-reproduction with characteristic of hypercycle. Self-reproductions in all of existent creatures need to be catalyzed by proteins which come from the translation of RNA. Hence all of these self-reproductions have charac- teristic of hypercycle.

The first life is called Luca. There must had been a lot of very complex non-living things before Luca occur. Complex things are difficult to emerge and easy to break. Though the world has trend of automatic evolution, the achievement of evolution cannot survive if its speed to emerge is smaller than the speed to break. Therefore, those complex non-living things cannot be seen by human. This would never have changed without self-reproduction. Hence, self-reproduction is the necessary condition of life origin. It is self-reproduction that makes it possible for complex structure to break the prison of the Second Law of Thermodynamics.

Creatures have many properties, including metabolism, growth, heredity, evolution and reflection, but not all kinds of creatures have all these properties. Self- reproduction in nature is the only property possessed by all creatures. The simplest creature can live without metabolism and growth, but cannot live without breeding.

Theorem: The necessary conditions of the origin of life is:

l A kind of material has relatively complex structure.

l It is able to self-reproduce in nature.

l This kind of structure is fit for some certain environment, i.e., it can make an index increasing of its number.

Therefore, these conditions are sufficient and necessary conditions of the origin of any life.

Openness, fluctuation, variation and natural selection are also necessary conditions of the origin of life, but they are not rare resources and are not considered here.

Bedau said, “To surmount the notorious difficulties of defining life, we should evaluate theories of life not by whether they provide necessary and sufficient conditions for our current preconceptions about life but by how well they explain living phenomena and how satisfactorily they resolve puzzles about life” (Bedau, 1998). But, if the real necessary and sufficient conditions for life are found, we shall be able to explain living phenomena and resolve puzzles about life in the easiest way. What is more, it is easy to deduce the definition of life after knowing the sufficient and necessary conditions of life origin.

Definition: Living substance is a kind of relatively steady and complex system with special structure, the structure enables it to have the function of making its structure survive in nature by self-reproduction and other positive feedback. The ability to make its complex structure survive by its own properties is vitality (life).

A lot of non-living things are able to survive steadily for a long time, but that depends on environment instead of properties of themselves. Some non-living systems have properties of positive feedback, for instance, laser, Benard instability, Belousov-Zhabotinskii reaction. But these structures of positive feedback are extremely unsteady, which is difficult to emerge and easy to break in nature. So they are not life.

There were more than 1 billion years before life emerged after the Earth had formed. What condition was absent for life origin during those years? All conditions had existed including natural selection, variation, fluctuation, openness, negative entropy and self- organization, except self-reproduction. The history of life began once the ability of self-reproduction emerge.

Ⅶ. Artificial Life

Research of artificial life has progressed greatly since 1987 when the first International Conference of Artificial Life was held. Artificial life, in fact, is nothing else than a kind of computer programs which are able to show some characteristics of life. The research of artificial life enlightens that it is possible for life to exist without components of carbon, hydrogen, oxygen, phosphorous and so on. Therefore, chemical ways is not necessary conditions of the origin of life.

Like molecular biology, though research of artificial life has progressed greatly it has not provided a precise answer of definition and essence of life finally. Though practice may promote the development of theory, it is not able to substitute theory, and needs guidance of theory. As products of man, some properties of artificial life can be added or eliminated, in order to prove whether these properties are sufficient and necessary conditions for their living. Experts of artificial life will do this kind of experiments, if they are aware that it is important to search sufficient and necessary conditions of life to solve the puzzle of life. It will be discovered by these experiments that none of characteristics, including metabolism, growth, evolution, adaptation and so on, is the sufficient or necessary conditions of the origin of life, and only self-reproduction is the sufficient and necessary condition of the origin of life.

On the other hand, artificial life is not real life, because it can only live in man-made environment. Artificial life dies once the electricity is cut down. Artificial life may be treated as real life with the premise of neglecting this condition. The research of artificial life only has value in theory, no value in practice has been found.

The second kind of artificial life is produced by scientists using biological technology, which is said to have become true (Gibson et al., 2010). But it, in fact, belongs to the product of genetic engineering, because not all materials of it are non-living things. Even it was possible for scientists to produce life with non-living materials completely, it is doubtful whether it would have more practical value than genetic engineering.

Two other kinds of artificial lives have real practical value, including nanometer robot and artificial intel- lectual robot. Nanometer robot is going to become life in natural environment without any premise, if it is able to reproduce itself. Nanometer robot is being studied in many countries with enormous investment. It will play positive role in many fields including engineering and medicine. At the same time, nanometer robot may bring huge disaster to human being. Nanometer robot may reproduce itself continuously without finish. They can even change all materials on the Earth including people and all products of people into nanometer robot. This is degeneration instead of evolution, and is the real disaster of the Earth.

By comparison, artificial intelligence is completely different with nanometer robot. Artificial intellectual robots will become real life once they are able to reproduce themselves. The development of artificial intelligence is evolution, even if they would massacre all human being just as many people worried (Garis, 2009). We do not need to worry about that, because artificial intelligence is able to learn the law that do not impose on others what you yourself do not desire. Man has faced various disasters. The risk of artificial intelligence is worthy to take, we should treat them as our children. Only artificial intelligence is able to eliminate all other disasters of people in the future.

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