150 was the estimated maximum size of neolithic tribes.

150 is the typical splitting point of a Hutterite farming village.

150 was the basic unit size of professional armies in Roman antiquity and has been ever since.

150 was set as the maximum number of people working in any one of their offices by the Swedish tax authorities in 2007.

150 is the average number of Facebook friends people have.

150 is the number of people human beings can, on average, maintain close, meaningful and personal relationships with. It’s the way we’re wired. Anything more, and we need to put structures in place that maintain social order, that provide guidelines that make social cohesion possible.