Saturday, April 5, 2008

Human Genetics Evolution

See also: Human evolution and Chimpanzee Genome Project

Comparative genomics studies of mammalian genomes suggest that approximately 5% of the human genome has been conserved by evolution since the divergence of those species approximately 200 million years ago, containing the vast majority of genes.[8][9] Intriguingly, since genes and known regulatory sequences probably comprise less than 2% of the genome, this suggests that there may be more unknown functional sequence than known functional sequence. A smaller, yet large, fraction of human genes seem to be shared among most known vertebrates. The chimpanzee genome is 95% identical to the human genome. On average, a typical human protein-coding gene differs from its chimpanzee ortholog by only two amino acid substitutions; nearly one third of human genes have exactly the same protein translation as their chimpanzee orthologs. A major difference between the two genomes is human chromosome 2, which is equivalent to a fusion product of chimpanzee chromosomes 12 and 13.[13]

Humans have undergone an extraordinary loss of olfactory receptor genes during our recent evolution, which explains our relatively crude sense of smell compared to most other mammals. Evolutionary evidence suggests that the emergence of color vision in humans and several other primate species has diminished the need for the sense of smell.[14]

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