Peter Godfrey-Smith - Metazoa - Animal Minds And The Birth Of Consciousness (William Collins, 2020) ****½

When does consciousness arise in animals? As of which point can we say that there is such a thing as consciousness? Zoologist Peter Godfrey-Smith has published books on the fascinating lives of the octopus, but in "Metazoa" he gradually works his way up the food chain to establish the different kinds of knowledge plants, microbes and animals get from the outside world and from themselves. 

Starting with the chemical reactions between cells and their environment (through ion channels), he explains how matter and energy start creating senses and brains: "these arrangements are not the causes of mind, they are minds. Brain processes are not causes of thoughts and experiences; they are thoughts and experiences". Because living things need energy to exist, they are in constant interaction with their environment to pick up signals, and to ingest nutrients. 

He gives a brilliant example of having a basic consciousness and a sense of self. Even the simplest animals have to be able to identify whether what they feel - through antenna, feelers, skin, or other - is the result of a predator touching them, or whether it is the result of their own movement touching something. At this stage the animal can discern between "self" and "other", as a prerequisite for survival. 

Godfrey-Smith is a great narrator, and his personal knowledge of marine biology, and especially on the octopus, is impressive and fascinating. Whether he's writing about corals, shrimp, crabs or other sea creatures, he brings it to a different level than just describing life under water. It is all about our brain, our experience, our sense of self, our mind.