hundred years of dominance starting in the 16 century. The Romans managed centuries of Mediterranean control. The secret of those long-running orders was something that will be familiar now: Each possessed tools of power which permitted assembly of empire at an unusually low cost in lives and gold and effort. Kauffman and his colleagues, as they considered the results of their survey, noticed each long-lived empire pioneered an administrative design that embodied an efficiency much like that of our own network dynamics. The addition of new territories brought more that they cost to masters of long imperial orders. Like new users on a social network, or Baran’s fish- nets, they married easy expansion and high returns. “Rome rose because it combined the strengths of traditional Republican institutions with innovations that gave it a unique capacity for inclusion of foreigners,” they explain. “Magadha was the most administratively durable of the ancient Indian states; and Qin, with the self- strengthening reforms of Shang Yang - economic reforms and military conscription as well as bureaucratic innovations - developed the most penetrating and brutally effective state structure in its international system.” The Incas, the Han, and nearly every long-standing empires glistened with this attractive logic. The secret to hegemony, to avoiding a violent power shifts every few decades, is a structure that grows without additional, destructive costs. When Machiavelli coldly called Rome a “republic for expansion”, this was what he had in mind. Enduring empires have been engineered, like a modern network, for growth and prosperity. It’s too early for us to know if this logic will obtain in our age. But networks evolve, as we've seen, to what makes them most efficient. They crave speed and growth. And this means they want cooperation; it’s the essential fuel for co-evolution. The traditional view of the international system as anarchic is not wrong, but we've seen how when you sna