In his book Other Minds – the octopus and the evolution of intelligent life Peter Godfrey-Smith goes back 600 million years to find the common ancestor of octopuses and humans. It was probably a simple worm-like creature, living at a time when no organisms had made it on to land.
Octopuses,squid and cuttlefish are all cephalopods, a class of molluscs. It also includes nautilus, which have distinctive external shells. Cephalopods are found all around the Australian coast, including on the Reef. PGS writes “Because our most recent common ancestor was so simple and so far back, cephalopods are an independent experiment in the evolution of large brains and complex behaviour. …evolution built minds twice over. This is probably the closest we will come to meeting an intelligent alien”.
The giant cuttlefish and octopuses that feature in Other Minds are remarkable animals. Octopuses have three hearts that pump blue-green blood, using copper as the oxygen-carrying molecule (our red blood uses iron). They are able to sense light and colour with their skin as well as with their highly developed but colour-blind eyes. They can recognise individual human faces and are clearly quite smart. They are able to morph their colours and shapes across a bewildering range of possibilities, making it very difficult to know if the animal you saw a few moments ago is the one you are seeing now. Some are masters of camouflage and impersonation.
This is a photograph of an octopus:
Here it is again, with labels
Octopuses are able to get from A to B by jet propulsion which they achieve by squirting water through an organ called a ’siphon’. Compared with us, their central brains and distributed nervous systems are more integrated, less separate. This is called “embodied cognition”.
Octopus and cuttlefish are just two examples. There are the countless other species of life in the sea, each wondrous in its own way. They are especially concentrated on coral reefs.
Other Minds provides a superb illustration of why marine science is important and worth supporting. The final sub-chapter begins with this observation: “The mind evolved from the sea. Water made it possible. All the early stages took place in water; the origin of life, the birth of animals, the evolution of nervous systems and brains, and the appearance of the complex bodies that make brains worth having.” It concludes: “When you dive into the sea, you are diving into the origin of us all”.