Peter Godfrey-Smith is an Australian philosopher and diving enthusiast, with particular interest in cephalopods, which goes someway to explaining this book. I did find it quite hard to absorb and switched to an audiobook part way through. I possibly missed something important but it seemed to drift from topic to topic and not really explain how the octopus can show us how human intelligence evolved.

You have to go a long way back the evolutionary tree to find a common ancestor between humans and octopus; our intelligence evolved in parallel. The book starts out explaining how single cell organised evolved into more complex creatures, how eyes might have coming into being and most importantly, the development of the nervous system. There was plenty of interesting bits but it was hard to just sit down and read it for long periods of time. It is a little dry in the delivery.

Godfrey-Smith recounts some of his experiences diving with cephalopods, including quite a moving scene where he sees cuttlefish at the ends of their lives; slowing decaying into the water. These creatures only live a couple of years and he ponders why they are as intelligent as they are in such a short lifetime. I loved the fact that Octopolis exists, a community of, usually anti-social, octopus living together off the coast of Australia.

Some of the experiments documented will be distressing to animal lovers, and octopus have only fairly recently been granted honorary invertebrate status to help protect them from cruelty.

It's not all about cephlapods though. There is a chapter about inner voice, how it's an important part of our intelligence. However it's not something scientists think octopus have, so I can only guess it was put in to show how we evolved differently.

If you are particularly interested in marine biology, I would say it's worth reading but it wasn't a very engaging "popular science" type book.