Within the nuclear eukaryotic genome there are two different information areas. One of these zones corresponds to coding DNA in which "structural genes" or "lower genes" can be found. On the other hand, disperse in the genome, there is the non-coding DNA, where redundant DNA can be found. In the latter area there are non-transcriptional genes or "higher genes" which arose with eukaryotic organisms as a result of coevolution. Viruses could have had an important role as natural vectors in the genomic evolution.