ABSTRACT
E: We turn to the discussion of the very controversial question: how did consciousness come into the biological world? I think for a start most would agree that animals differ from plants or, shall we say, higher animals differ from plants in that they have a nervous system which is a highly specialized part of the organism that is concerned with picking up information and reacting to it. This gives animals a performance quite different from that of plants, which are essentially organisms that have a much more passive role in their whole existence, sessile and not as a rule evincing any responses except those of growth and turgor. When we come to survey the whole sequence of biological evolution of animal forms and behaviours, then if you wish you can see all kinds of purposive actions in primitive organisms, even in protozoa such as amoeba or paramoecium. If you examine the higher animal level, the multicellular organism, you can see, as in coelenterates, a primitive nervous system that develops appropriate reflex reactions in response to stimuli. So it goes on in the whole of the invertebrate story into quite complex forms with complex reactions as, for example, in the higher insects. We are all familiar with the bee’s ability to learn its environment so that when its hive is changed, it can do a few circuits around and learn the way home when it goes out on its flights. That is a learning response and then of course we are familiar with the information given symbolically in the dance of the bees. Finally at the top of the invertebrate tree there are the still more highly developed nervous systems of the higher molluscs. The octopus for example has been studied in detail by J. Z. Young, who has shown that it has a highly developed brain with most complex responses to signals, and the ability to learn. Now, that is the summit of the invertebrate story and I think we could now question and ask: is there evidence that invertebrates have some kind of responses of their brain which could be classed as giving conscious experiences?
