Picture an imperfect hall of mirrors, with gene sequences reflecting wildly: That's the human genome. The duplications that riddle the genome range greatly in size, clustered in some areas yet absent in others, residing in gene jungles as well as within vast expanses of seemingly genetic gibberish. And in their organization lie clues to genome origins. "We've known for some time that duplications are the primary force for genes and genomes to evolve over time," says Evan Eichler, director of the bioinformatics core facility at the Center for Computational Genomics, Case Western Reserve University, Cleveland. For three decades, based largely...