DNA sequencing reveals that the genomes of the human, gorilla and chimpanzee 
share more than 98% homology. Comparative chromosome painting and gene mapping 
have demonstrated that only a few rearrangements of a putative ancestral 
mammalian genome occurred during great ape and human evolution. However, 
interspecies representational difference analysis (RDA) of the gorilla between 
human and gorilla revealed gorilla-specific DNA sequences. Cloning and 
sequencing of gorilla-specific DNA sequences indicate that there are repetitive 
elements. Gorilla-specific DNA sequences were mapped by fluorescence in-situ 
hybridization (FISH) to the subcentromeric/centromeric regions of three pairs of 
gorilla submetacentric chromosomes. These sequences could represent either 
ancient sequences that got lost in other species, such as human and orang-utan, 
or, more likely, recent sequences which evolved or originated specifically in 
the gorilla genome.