many worlds. Data companies face increasing bandwith demands. They develop new ways to transmit video. Application developers create fresh tools to compress their signals. The whole system gets faster. Such co-evolution is common when linked systems press into one another.?5! If you look back at biological history, at our planet’s seething life at it’s most profound moments of transition, you find co-evolution in nearly every case. The biologists John Maynard Smith and Eors Szathmary, in their masterwork The Major Transitions in Evolution, chronicle the miraculous march of life towards ever-greater complexity — from cells to humans to societies — as a story of ceaseless, successful co-evolution. “Complexity is hard to define or to measure,” they write. “But there is surely some sense in which elephants and oak trees are more complex than bacteria, and bacteria than the first replicating molecules.” The essential, facilitating feature of our biological hop-scotch from mitochondrial snot to Beethoven sonatas has been an ability to change together, not merely to compete. While we humans tend to consider evolution in murderous you win/I lose Darwinian terms, the biological world around us seethes with a more nuanced logic: Cooperation is every bit as important to survival. Smith and Szathmary identified eight major transitions in their work - the evolution from single cell to multiple cell organisms, for instance. And in each case they find a kind of cooperative, co-evolving logic serving a catalyst to survival. “The applicability of the concept,” Smith and Szathmary conclude, “extends across the whole of social and natural sciences.” Inside cells. In ecosystem webs of coral or rainforest. In traffic management. Successful evolution was, they found, always co- evolution. “It should need little persuasion to acknowledge that links we make with others change in time,” they wrote. “That all of us age, that our roles in life evolve, and that the society we are a part of may