Cephalopods and the evolution of the mind.

Abstract

IN thinking about the nature of the mind and its evolutionary history, cephalopods — especially octopuses, cuttlefish, and squid — have a special importance. These animals are an independent experiment in the evolution of large and complex nervous systems — in the biological machinery of the mind. They evolved this machinery on a historical lineage distant from our own. Where their minds differ from ours, they show us another way of being a sentient organism. Where we are similar, this is due to the convergence of distinct evolutionary paths. I introduced the topic just now as ‘the mind.’ This is a contentious term to use. What is it to have a mind? One option is that we are looking for something close to what humans have — something like reflective and conscious thought. This sets a high bar for having a mind. Another possible view is that whenever organisms adapt to their circumstances in real time by adjusting their behaviour, taking in information and acting in response to it, there is some degree of mentality or intelligence there. To say this sets a low bar. It is best not to set bars in either place. Roughly speaking, we are dealing with a matter of degree, though ‘degree’ is not quite the right term either. The evolution of a mind is the acquisition of a tool-kit for the control of behaviour. The tool-kit includes some kind of perception, though different animals have very different ways of taking in information from the world. It includes some form of memory and learning, means by which past experiences can be brought to bear on the present. In some cases it includes problem-solving and planning. Some tool-kits are more elaborate and expensive than others, but they can be sophisticated in different ways, with different tools present and more investment in one technology than another. One animal might have better ways of tracking the environment through its senses, while another may have simpler senses but more sophisticated learning. Different tool kits go with different ways of making a living. The ordinary term ‘mind’ is awkwardly or misleadingly applied to an animal with a very simple behavioural repertoire, but it is parochial to apply it only to humans.