Comparing primate genomes is an approach that can help scientists understand the genetic basis of the physical and biochemical traits that distinguish primate species. James Sikela and colleagues, for example, collected DNA from humans, chimpanzees, bonobos, gorillas, and orangutans to identify variations in the number of copies of individual genes among the different species. Their work is published in this month's issue of the open-access journal, PLoS Biology.
Overall, Sikela and colleagues found more than 1,000 genes with changes in copy number in specific primate lineages. All the great ape species showed more increases than decreases in gene copy numbers, but humans showed the highest number of genes with increased copy numbers, at 134, and many of these duplicated human genes are implicated in brain structure and function.
Because some of these gene changes were unique to each of the species examined, they will likely account for some of the physiological and morphological characteristics that are unique to each species. One cluster of genes that amplified only in humans was mapped to a genomic area that appears prone to instability in human, chimp, bonobo, and gorilla. This region has undergone modifications in each of the other descendent primate species, suggesting an evolutionary role. In humans, gene mutations in this region are also associated with the inherited disorder spinal muscular atrophy. This fact, along with the observation that there are hu