There is no more urgent question in global affairs today: Can the United States and China find a way to coexist—or are they on a collision course that threatens the entire planet?

In Darwin’s Lock, Joshua Cooper Ramo offers a brilliant new analysis of the most important geopolitical relationship of our time. Beginning with Charles Darwin’s concept of evolution—widely considered the most powerful idea in all of science—Ramo argues that the destinies of America and China are locked together. The choice is not between which nation will win any future struggle, but between what biologists call coevolution and coextinction.

Drawing on more than two decades at the forefront of American foreign policy and China business, Ramo leads readers through a clear-eyed examination of what is really at stake between the two nations. Touching on everything from the history of Chinese urban design to the lessons of nuclear weapons brinkmanship to Ramo’s firsthand experience of the wobbly bridge between the two great powers, Darwin’s Lock presents a truly novel framework for US-China relations.

Can the US and China avoid the killing trap of nationalist competition? Ramo offers a set of innovative science-based experiments that can turn both countries toward a more rational path. It’s an approach that will make each nation more fit, more secure and better able to help the world confront the dangers of our age. Urgent, hopeful and deeply informed, Darwin’s Lock is essential reading for anyone who wants to understand where the world is headed—and what it will take to get there safely.