His lab studies the evolutionary processes that give rise to genetic and phenotypic differences between individuals, populations, and closely related species. They use mathematical models to better understand these processes, and statistical analyses to identify their footprints in data and make inferences about them. Current work in the lab focuses primarily on the evolutionary causes of adaptation and disease, but also on a variety of other topics. Before joining Columbia, Sella was a faculty member at Hebrew University (Israel) and a visiting professor at Stanford University.