In Green Equilibrium, award-winning field biologist Christopher Wills explains the rules by which ecosystems thrive, shining light on a set of ecological balancing acts that he calls "green equilibria," rules which keep our world vibrant, verdant, and ecologically intact.

To explain the idea of "green equilibrium," Wills draws on a fascinating range of examples, including coral reefs off the densely populated Philippines, the isolated and thickly forested valleys of Papua New Guinea, the changing Himalayan kingdom of Bhutan, and a Californian ranch being allowed to return to a wild state. Wills travels to Guyana's rainforests and savannahs, for instance, to provide startling vignettes of ecological processes in action. Among other topics, he highlights the astonishing snake-head mimicry that swallowtail caterpillars use to scare off predators, the symbiotic relationship between the exceedingly rare Golden Poison-Dart Frog and the tank bromeliad plant, and the invisible world of pathogens and parasites that helps to drive diversity. All these mechanisms, and many more, maintain the "green equilibria" of Guyana's rainforest ecosystems. Wills also shows how "green equilibria" have shaped the evolution and history of our own species. We now know that a kind of genetic "green equilibrium" helped populations adapt to changing environmental conditions as they spread out of Africa. Striking new evidence indicates that some modern human populations still carry genes from past hominids (such as the Neanderthals) as well as genetic adaptations to local hazards such as malaria.

Traveling to many different ecosystems, from coral reefs to the high Himalayas, and drawing on his own on-the-ground research, Wills illuminates ecological laws in action. Perhaps most important, he introduces us to people, in many countries around the world, who are now using this new knowledge to help heal the planet.