With the sequencing of human genome nearing completion, there was a lot of interest in applying comparative genomics approaches to help unlock the secrets of the human genome. Dr. Roskin worked with David Haussler as part of the Mouse Genome Sequencing Consortium. Their goal was to analyze the genomic differences between mammalian species to find regions of the human genome that are conserved not by chance but because of evolutionary constraint. To that pairwise analysis, Dr. Roskin added data from the Rat Genome Sequencing Consortium to allow triangulation of evolutionary events across the whole genome.
A major result in the Mouse genome paper was Dr. Roskin's estimate of the share of the human genome under purifying selection. He developed score functions to detect unusually conserved regions in the human genome by comparing it to the mouse. By looking at the distribution of conservation scores genome-wide compared to the scores of regions under neutral section, he estimated that 5% of human genome is under purifying selection. This percentage is much higher than the fraction of the genome that codes for proteins and spurred new interest in function non-coding elements of the human genome.