"Other Minds: The Octopus and the Evolution of Intelligent Life" by Peter Godfrey-Smith

This is a beautifully written book about the intelligence of octopi and cuttlefish which are cephalopods. “If we can make contact with cephalopods as sentient beings, it is ... because evolution built minds twice over. This is probably the closest we will come to meeting an intelligent alien.” (p 9) Along the way it becomes an enquiry into what it means to have a consciousness. “For some animals, there's something it feels like to be such an animal. there is a self, of some kind, that experiences what goes on.” (p 10)

It starts tracing the evolution of the nervous system. After all, even bacteria can react to stimuli and therefore may be said to have some version of sentience:

• “The bacterium will swim in a straight line as long as the chemicals it senses seem better now than those it sensed a moment ago. If not, it’s preferable to change course.” (p 17)

The crucial factor is that the bacteria can in some sense detect the actions they themselves take. This feedback loop between sensory input and action and sensory input is the beginning of self awareness. And because one bacterium can detect things that other bacteria do it is the beginning of communication and socialisation. So when cells begin to get together in multicellular organisms we have the rudimentary mechanisms for a nervous system.

• “The receptors on the surfaces of bacterial cells are sensitive to many things, and these include chemicals that bacteria themselves tend to excrete” (p 18)
• “If a chemical is both produced and sensed by a particular kind of bacteria, it can be used by those bacteria to assess how many individuals of the same kind are around.” (p 18)
• “Chemicals that are made because they'll be perceived and responded to by others ... brings us to the threshold of signalling and communication.” (p 19)

At this stage I was getting excited. After all, Andy Clark in Surfing Uncertainty, working in the world of artificial intelligence, suggests that a computationally frugal solution for intelligence involves an organism making an expectation and comparing the sensory data with the expectation so that a simple error reduction algorithm can improve the expectation. This involves a feedback loop and here we see something similar being evolved from the simplest forms of cellular life.

G-S gives an example in technology developed to aid the blind. There is a system that uses a camera to change vision into tactile sensations on the skin of a blind person. The person soon learns to experience “objects located in space” BUT “only when the wearer is able to control the camera.” (p 80)

Of course, multicellular life had to evolve before cell specialisation could start developing proper nervous systems. But this wasn't as difficult as it might at first look. It has evolved independently more than once. “The transition to a multicellular form of life occurred many times, leading once to animals, once to plants, on other occasions to fungi, various seaweeds, and less conspicuous organisms.” (p 20)

And once predation begins (probably in the Cambrian) each organism must be aware of the others which adds further urgency to the evolution of sensory-action feedback loops. “From this point on, the mind evolved in response to other minds.” (p 36)

The only thing that makes animals different is that they have greater capacity to take actions and so need to be even faster at sensing their own actions. “All living things affect their environment by making and transforming chemicals, and also by growing and sometimes by moving, but it is muscle that gives rise to rapid, coherent action on large spatial scales. It makes possible the manipulation of objects, the deliberate and rapid transformation of what is around us.” (p 82) This “interaction between perception and action” is critical. (p 83)

And the next stage for feedback loops is our own thoughts. G-S suggests that the internalization of language, “Vygotsky’s transition ... was also an important evolutionary event.” (p 152) He spends some time on inner speech:

• “When we look inside, most people find a flow of inner speech, a monologue that accompanies much of our conscious life.” (p 138)
• “Ordinary speech functions both as input and output ... We both speak and hear, and we can hear what we say. Even talking to yourself out loud can be a useful way of approaching a problem.” (p 144)
• “In speech, the creation of an efference copy enables you to compare your spoken words to an inner image of them; this can be used to work out whether the sound ‘came out right’.” (p 145)
• This then means that we can “put together sentences that we don't intend to say, sentences and fragments of language that have a purely internal role. ... We can put things in order, bring possibilities together, can list and instruct and exhort.” (p 147) This is particularly useful for Kahneman’s [ref Thinking, Fast and Slow] “System 2” thinking, the “slow, deliberate style of thinking we engage in when we encounter novel situations ... [which] tries to follow proper rules of reasoning, and tries to look at things from more than one side.” (p 147)
• This resonates with the “workspace theory of consciousness” (p 149)
• Inner speech is especially prominent when “we bring attention to bear on our own thought processes, reflect on them, and experience them as our own.” (p 152)
• “When you write something for yourself to read ... it is a communication between your present self and a future self.” (p 155)

There is also an interesting argument about ageing. Why do species age at different rates: trees last hundreds of years, humans perhaps a hundred, cephalopods mostly two? The idea is that “When molecular accidents put mutations into the population ... the late-acting mutations will be cleaned out less efficiently than early-acting ones.” (p 166) “So mutations with good effects early in life and the bad effects later in life will accumulate; natural selection will favour them.” (p 167) Therefore some populations have evolved such that the bad mutations tend to affect them later in life ... and it seems like spontaneous ageing. The life-span is thus partly a matter of evolutionary chance and partly governed by the balance of reproduction and predation. When the octopus lost its hard shell it became much more susceptible to predation which meant that it had to live its life a lot quicker because, sooner or later, a sharp-toothed fish would eat it. Presumably humans are mostly prey to diseases which, sooner or later, will get them, so they are able to evolve genes which allow then to fight the diseases for a while even at the cost of dying later.

Other thoughts from this brilliant book:

• Cuttlefish sometimes deeply ignore visitors to their watery world. “Being ignored so deeply makes you wonder if you are entirely real in their watery world, as if you are one of those ghosts who does not realise they are against.” (p 118)
• “When animals did crawl onto the dry land, they took the sea with them. All the basic activities of life occur in water-filled cells bounded by membranes, tiny containers whose insides are remnants of the sea.” (p 200)

A readable and intensely thought-provoking book. March 2018; 204 pages

The author has now written a sequel: Metazoa: Animal Minds and the Birth of Consciousness

This review was written by the author of Motherdarling  and The Kids of God