What evolutionary mechanisms might account for the origin and persistence of cell-to-cell signaling in unicellular prokaryotes?

The concept of cell signaling is a communication network that is responsible for majority of the cellular activities. It is important that if the cell is deprived of this ability it will soon die. Since a cell is able to correctly interact with it's environment and perceive it, they are able to repair tissues, develop, and become immune to normal tissue homeostasis.