U.S. geneticists believe they know why humans are so different from chimps, although sharing most of the same genes: it's how the genes are used.
After studying the regulatory sequences adjacent to 6,280 genes in the DNA of chimps, humans and the rhesus macaque, scientists determined the differences center mainly on traits involving brains and diet. It's rather like the same set of notes being played in very different ways.
Positive selection, the process by which genetic changes that aid survival and reproduction spread throughout a species, has targeted the regulation of many genes known to be involved in the brain and nervous system and in nutrition.
Although many studies have looked for significant differences in the coding regions of genes relating to neural system development and failed to find any, the Duke team believes its study is the first to take a genome-wide look at the evolution of regulatory sequences in different organisms.