“…In addition to amino acid substitution, divergence at a transcriptional level, such as cis-regulated gene expression divergence and the gainand-loss of genes, is likely to be an important factor in the genomic evolution of organisms to create phenotypic complexity (King and Wilson, 1975;Enard et al, 2002a;Heissig et al, 2005;Marques et al, 2005;Rockman et al, 2005). Although gains-and-losses of genes might cause a larger phenotypic effect than single amino acid substitutions (Olson and Varki, 2003), fewer studies have described lineage-specific gains-and-losses of genes among higher primates (Chou et al, 1998;Stedman et al, 2004;Hahn and Lee, 2005;Hayakawa et al, 2005;Wang et al, 2006), with the exception of the frequent births and deaths of genes in large multi-copied gene families (Meyer Olson et al, 2003;Fortna et al, 2004;Gilad et al, 2005;Go et al, 2005). Using the human and chimpanzee genome sequence, we could conduct a genome-wide survey of species-specific pseudogenes, which carry null mutations in the coding region either in the human and chimpanzee (Hahn and Lee, 2005;Wang et al, 2006).…”