How multicellular life forms evolved out from unicellular ones constitutes a major problem in our understanding of the evolution of our biosphere. A recent set of experiments involving yeast cell populations has shown that selection for larger aggregates leads to the appearance of stable clusters of cells that are able to split into smaller aggregates. It was suggested that the observed evolutionary patterns could be the result of evolved programs affecting cell death. Here we show, using a simple model of cell-cell interactions and evolving adhesion rates, that the observed patterns in cluster size and localized mortality can be easily interpreted in terms of diffusion-limited growth dynamics. An experimental test of this scenario is proposed. This simple mechanism would have played a key role in the early evolution of multicellular life forms based on aggregative development. The potential extensions of this work and its implications for natural and synthetic multicellularity are discussed.
Emergence of multicellularity in a model of cell growth, death and aggregation under size-dependent selection
Salva Duran-Nebreda, Ricard V. Solé