Living on Earth by Peter Godfrey-Smith 

The eagerly anticipated conclusion to Peter Godfrey-Smith’s three-part exploration of the origins of intelligence on Earth, which began with the bestselling Other Minds in 2018 and continued with Metazoa in 2020.

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 visits the largest living stromatolite fields, examples of how cyanobacteria began belching oxygen into the atmosphere as they converted carbon dioxide and water into living matter using the sun’s light. The extraordinary increase in oxygen in the atmosphere resulted in an explosion in the diversity of life. And so began a riotous tangle of coevolution between plants and animals, as each changed the environment around them allowing others to utilise these new ecosystems and thus new species to evolve. From cyanobacteria, through algae on to ferns or trees or grasses, and from protists , through invertebrates and fish through the dinosaurs and on to birds and mammals – our planet has seen an explosion of life forms, all reacting to their environment and all creating new environments that allow other life to evolve.

In our own evolutionary line, an initially unremarkable mammal changed in new ways, evolving to come out of the trees to inhabit new savannas and then onto inhabit the whole planet. One of the most adaptable species ever found on Earth, and arguably the species causing the most change, humans are still part of this 3.8 billion year history of life forms changing the world around them.