In a recent paper in the Proceedings of the National Academy of Sciences, School of Biological Sciences Associate Professor William Ratcliff and Emma Bingham, student in the Interdisciplinary Graduate Program in Quantitative Biosciences, put forward a brand new idea, which they tested in a computational model. Bingham and Ratcliff suggest that the way prokaryotic and eukaryotic genomes respond to population size may make or break their chances of evolving multicellularity. It’s a fascinating hypothesis, and if further work bears it out, it could fundamentally change how scientists conceive of this transition and challenge a key assumption they make about evolutionary forces.