Both evolution from unicellular to multicellular organisms and development of complex organisms from one cell to the final body plan require specific cellular features. Unicellular organisms or fertilized eggs are virtually pluripotent. As body plans complexify and pluricellularity emerges cells will become specified and more and more differentiated and they will have to realise specific tasks. Therefore, organisms will have to develop means of cellâ cell communication, cells will have to maintain cohesion and adhesion between each other, organisms will have to find ways to reproduce and to repair or regenerate specific cells or tissues. We will review points that characterise this passage from unicellular to pluricellular organisms using specific examples taken from evolution and development.