I have seen estimates that show civilization at its current size is only possible when energy gains are 12 to 1 or better (energy return on energy invested in energy projects). We are quite near that 12 to 1 ratio. That implies devolution – minimizing the cost of administration.

( About 7 and 1/2 minutes )

Neocortex size as a constraint on group size in primates – R. Dunbar 1991