The concept of organic evolution implies descent of all living and extinct forms from one or more common ancestors in the distant past of earth history. During recent decades, traditional phylogenetic deductions from the anatomy of living and fossil organisms have been supplemented by a vast and growing new body of molecular evidence. Each living creature contains a genome consisting of linear sequences of DNA bases, millions or billions of them, which determine all the developmental, anatomical and physiological characteristics of that species. This DNA is transcribed into messenger RNA (mRNA) which uses the machinery of the cell to make proteins. The sequence of mRNA bases determines the sequence of amino acids of the resultant protein (Lowenstein, 1986).