The human and chimpanzee genomes vary by just 1.2 percent, yet there is a considerable difference in the mental and linguistic capabilities between the two species. A new study showed that a certain form of neuropsin, a protein that plays a role in learning and memory, is expressed only in the central nervous systems of humans and that it originated less than 5 million years ago. The study, which also demonstrated the molecular mechanism that creates this novel protein, will be published online in Human Mutation, the official journal of the Human Genome Variation Society.