- 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.