While humans differ from chimpanzees in approximately 1-2% of the "letters" (nucleotides) of their genome, a new paper shows that as much as 80% of human proteins are different from those of chimpanzees. This shows how a small degree of genetic difference may have large overall effects.
Gene (Article in Press)
Eighty percent of proteins are different between humans and chimpanzees
Galina Glazko et al.
The chimpanzee is our closest living relative. The morphological differences between the two species are so large that there is no problem in distinguishing between them. However, the nucleotide difference between the two species is surprisingly small. The early genome comparison by DNA hybridization techniques suggested a nucleotide difference of 1–2%. Recently, direct nucleotide sequencing confirmed this estimate. These findings generated the common belief that the human is extremely close to the chimpanzee at the genetic level. However, if one looks at proteins, which are mainly responsible for phenotypic differences, the picture is quite different, and about 80% of proteins are different between the two species. Still, the number of proteins responsible for the phenotypic differences may be smaller since not all genes are directly responsible for phenotypic characters.