I was not surprised when scientists recently confirmed that skin was the first organ of a multi-cellular organism (sponge) to evolve. I would argue that without a skin a multi-cellular organism is just a bunch of cells, not a multi-cellular organism. The skin determines what’s in and what’s out and in doing so needs some type of identity. Then the cells need to communicate with each other, specialise and so forth. The rest is evolution.
The same goes for multi-cellular organisms forming organisations, organisations forming societies and societies forming not-sure-yet-what.
Klaas⋄Live 