Other Minds: The Octopus and the Evolution of Intelligent Life

by Peter Godfrey-Smith

It’s not that the loss of a shell alone created the evolutionary pressure leading to those nervous systems. Rather, a feedback system was established. The possibilities inherent in this body create an opportunity for the evolution of finer behavioral control. And once you have a larger nervous system, this makes it worthwhile to further expand the body’s possibilities – collecting all those sensors on the arms, creating the machinery of color change and a skin that can see. The loss of the shell also had another effect: it made the animals much more vulnerable to predators, especially fast-moving fish, with bones and teeth and good vision. That put a premium on the evolution of wiles and camouflage. But there is only so much those tricks will achieve, only so many times they will save the animal. An octopus can’t expect to live a long time, especially as they must be active as predators themselves. They can’t just hide in a hole and wait for food to come to them. They have to be out and about, and once in the open they are vulnerable. This vulnerability makes them ideal candidates for the Medawar and Williams effects to compress their natural lifespan; a cephalopod’s lifespan has been tuned by the continual risk of not making it to the next day. As a result, they have ended up with their unusual combination: a very large nervous system and a very short life. They have the large nervous system because of what those unbounded bodies make possible and the need to hunt while b...