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The epigenome regulates the gene expression of all differentiated cells and indicates which specific genes must be transcribed. It is argued that the expression factors that act in specific genes of the somatic cells involved in a behavior also act in the partial transcription of the same genes in the most undifferentiated cells of the germ line. It is proposed how a probabilistic view of the random mutation can explain the evolution of the phenotypes and integrate all the evidence pointing to a conjunct evolution with the environment.
A paragraph was added that argues the relationship between the levels of transcription and the presence of isochores. Two new addresses were added as a proposal to the field of study. Two references were withdrawn due to because they were considered not relevant information. The ideas and arguments origunals remain the same as in the first publication. With the addition of four new references, the previous bibliographic information has been enriched.