According to this recent physics study, cooperative behavior is stimulated by literal fluid flow.

“In a new study, physicists at the University of Notre Dame examined how the mechanical properties of an environment may shape the social evolution of microbial populations. Through computer simulations and analytical calculations, they determined the necessary properties of diffusion and flow that allow microbes to evolve stable social behavior. Their findings also allow for speculation that the evolution of single-cell organisms to multicellular organisms may have taken place in flowing fluids like rivers or streams as opposed to larger bodies of water such as oceans and lakes.”

Turns out “go with the flow” is much more than a metaphor. We need to circulate among each other to survive, let alone to thrive.