  Development combines three basic processes asymmetric --- cell division,
signaling and gene regulation --- in a multitude of ways to create an
overwhelming diversity of multicellular life-forms. Here, we attempt to chart
this diversity using a generative model. We sample millions of biologically
feasible developmental schemes, allowing us to comment on the statistical
properties of cell-differentiation trajectories they produce. Our results
indicate that, in contrast to common views, cell-type lineage graphs are
unlikely to be tree-like. Instead, they are more likely to be directed acyclic
graphs, with multiple lineages converging on the same terminal cell-type.
Additionally, in line with the hypothesis that whole body regeneration is an
epiphenomenon of development, a majority of the `organism' generated by our
model can regenerate using pluripotent cells. The generative framework is
modular and flexible, and can be adapted to test additional hypotheses about
general features of development.
