Owing to interaction of a genotype and the external environment the genotype is shown in it in the form of a number of signs (phenotype): the number of signs has compliance with number of genes.
The most harmonious interaction of an organism through a phenotype with the environment is noted by natural selection in competitive struggle of organisms with fixing in chromosomes of the genes corresponding to these signs, with the subsequent inheritance of the fixed genes. Descendants thereby receive genes which determine emergence of these or those signs. Material for natural selection are, as a rule, random changes (mutations) of the genotype as a whole or any part of it. Mutations can be harmful or beneficial for the organism depending on the conditions of its existence [1. Ch. 3].
In this short description there are no answers, at least, on two major questions: from where emerged the first simplest organisms with predetermined programs on the protein carrier. and why the genotype of organisms began to become complicated.
Indeed, the spontaneous formation of the simplest programs on the protein carrier has the probability close to zero, even in the calculation for billions of years. This fact implies the impossibility of spontaneous appearance of the living beings, who, however, has appeared on Earth.
Complication of the elementary organisms the genetics explain by the arbitrary character of this phenomenon, that in itself isn't scientific, inasmuch the complex process of natural selection is given at the mercy of arbitrariness, whereas any live organism acts in strict accordance with the program which is available in the genome. This program assumes use of any failures (mistakes) during realization, in particular, the programs of replication, by means of remembering and application, at their positive influence on the reproduction process, fixing these failures in the available program, i.e. adding an extra combination of links to the former links, recorded in the program.
Thereby this procedure, on the one hand, increases number of combinations of links in a genome, complicating it, and on the other hand, this process of use of new links, positive for replication, in effect, means gradual formation of some kind of reflexes on the remembered irritation that, naturally, is reflected on a phenotype.