The origin of multicellular animals from their perspective of their unicellular relatives

How animals emerged from their unicellular ancestors remains a mystery. To address this question, we first obtained genome data from the closest unicellular relatives of animals. Comparative genomic analyses demonstrated that the unicellular ancestor of animals was relatively quite complex, with genes involved in cell-adhesion, cell communication and cell differentiation. Moreover, we showed as well that many animal-like features of genomic regulation and spatial cell differentiation were also present in the unicellular ancestor. How those processes were co-opted and expanded, and how different cell types evolved remains unclear, and is the core of our current work. Overall, all the data generated from the closest unicellular relatives of animals allow us to challenge previous views of animal origins and propose a new perspective on how animals evolved.