All multicellular organisms are made up of cells with distinct fates. What mechanisms ensure that cells know how to divide, move, and differentiate in ways that will ultimately generate a functional organism? Can we answer these questions without a priori knowledge of the genes they express or the molecules they contain, in a way that might be generalizable to other organisms? I will describe the results of our efforts to do just that, using a cricket laboratory model organism, quantitative image analysis, mathematical and computational models, and physical manipulation of developing embryos. We found that mechanisms that can explain some of early development in the fruit flyDrosophila melanogaster, cannot explain analogous processes in the cricket Gryllus bimaculatus. Instead, our observations suggested a novel nuclear-density-dependent mechanism regulated the first steps of cricket development. This model was supported by the results of experiments where we increased or decreased nuclear density within early embryos. I will discuss whether and how we think this model might apply to other insect embryos or animal cells, and how such mathematical modeling approaches might allow us to understand general principles governing the function and evolution of developmental mechanisms.