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.