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.