Based on a systematic analysis of the mitochondrial genome, Radek Szklarczyk and Martijn Huynen at Radboud University Medical Center in The Netherlands were able to estimate that "the mitochondrial proteome expanded at least 50% since the common ancestor of human and yeast." The authors' work, which appears this week in Genome Biology, found that gene duplications led to the expansion in humans, and that the most common of these are intra-mitochondrial and inter-compartmental.