Gene duplication has had a significant impact on all genomes and the human genome is no exception, as gene duplication contributes much of the raw material from which natural selection shapes novel genes. In the context of human evolution, interest in gene duplication has been intense as the human genome is particularly rich in duplicated genomic regions. These duplicate genes contribute to genomic instability, leading to genome rearrangement and speciation. Recent evidence suggests that duplicated genes have undergone greater diversification than other loci in the human lineage, and so have been key in the evolution of uniquely human traits.