Genomes, or the biological information needed to create and maintain a living organism, have been partially mapped for a number of species, including humans. The guidelines in a genome are encoded in an organism's deoxyribonucleic acid, hereditary material which provides a blueprint for replicating individual examples of the organism. By comparing sequences of DNA from humans and other species, researchers have discovered close and unexpected connections.
Numerous studies have established a near-total match between human DNA and that of chimpanzees, with 95 to 98 percent correspondence. Although the match between humans and other apes such as monkeys and gorillas is slightly less, these figures indicate that the gap between humans and apes is small. Ongoing research on the human and ape genomes focuses on exploring those differences, which appear to account for human characteristics such as speech and some cognitive patterns.
Although chimpanzees are the nearest relatives of humans, a number of other mammals also share significant amounts of DNA with humans. Portions of the human chromosome 6 have a match in DNA samples from pigs, cows and domestic cats. Dogs, rats, mice and even chickens also share DNA sequences with humans. Since mapping of the human genome and those of other animals continues, more correspondences are expected to emerge.
Matches have been found between sequences of human DNA and those of other types of creatures, such as the reef building coral (Acropora millepora), whose DNA contains sequences that correspond to human genes which map the nervous system. Studies of these correspondences hold promise for research into diseases of the nervous system and for the broader examination of evolutionary processes leading to differentiation in DNA sequences.