In Science this week, researchers at the University of Washington School of Medicine and members of the 1,000 Genomes Project, along with their industry colleagues, report their analysis of the "diversity of human copy number variation and multi-copy genes." In their investigations of 159 human genomes, the team found more than 4 million "'singly unique nucleotide' positions informative in distinguishing specific copies," as well as "human-specific expansions in genes associated with brain develop