He helped develop the process of separating helium from natural gas and participated in the creation of the bureau’s mine-safety division. He was director (1922–27) of the Fixed Nitrogen Research Laboratory of the U.S. Department of Agriculture, where he helped develop the synthetic ammonia ...
So then you can have societies of millions of people, and lots of specialist niches and efficient division of labor, and a cool pyramid to model the hierarchy, and large accumulations of capital and land and labor so you can do the big things like dams and roads that create civilization....