Peter Godfrey-Smith, the scuba-diving philosopher, examined the evolution of sentience in Other Minds. In Metazoa he asked how that consciousness shaped and was shaped by animal bodies.

Now, in Living on Earth, he takes that line of questioning a step further, asking, how has life shaped and been shaped by our planet? He explores the last living stromatolite fields, examples of how cyanobacteria from the sea first began colonising the land and belching oxygen into the atmosphere as they photosynthesised the sun's light.

Oxygen meant life, and so began a riotous tangle of coevolution between plants and new animals. And then, in our own evolutionary line, an initially unremarkable mammal changed in new ways, forming societies and technologies. This led eventually to change to the atmosphere itself, as carbon that was buried and transformed to oil was deliberately burned with life-derived oxygen, to power the elaborate world of humanity.

Humans belong to the infinitely complex system that is the Earth, and our minds are products of that system, but they are also an acting force within it. We are creatures of Earth, and we hold Earth's future in our hands.