Updated 17 April 2021
Who would expect to see complex social behaviour demonstrating cognition in a manta ray or an octopus? Yet both species have the brain structures necessary to support consciousness and both display advanced cognitive behaviours. By any objective crieria, such as those expressed in The Cambridge Declaration on Consciousness> (pdf), they are conscious, sentient beings like ourselves. They are chaning our ideas on what it means to be human.
One day Freckles got some fishing hooks caught under an eye. Some marine researchers had been diving in her area regularly and she had got used to them. But what happened next was unprecedented. She swam up to them and asked for them for help, repeatedly rearing up to show them the problem until one of them could get the hooks out. They spent a moment more close to each other, then she circled him, apparently in a show of gratitude, before swimming off.[1]
Many fishermen claim that fish are too simple and primitive to feel pain, they are not sentient beings. But of all the weird and random things that can happen to a manta ray in the untamed oceans, why should Freckles single out the fish hooks for medical attention if they did not hurt like blazes?
The manta ray clearly feels pain, or at least some cognitive equivalent. But does that necessarily mean that it is consciously aware, that it subjectively experiences something like creativity and pain? Might its abilities simply be hardwired by evolution?
Behaviourism was a theory, very fashionable at one time, which held that scientifically speaking even the human mind was hardwired, or at least programmed, in this way. The harder behaviourists regarded that as carte blanche to treat inner experience as fundamentally nonexistent, an extreme which even its arch protagonist, B.F. Skinner, confined only within the laboratory. Nowadays we are sophisticated enough to have demonstrated the crudity and inadequacy of behaviourism in explaining the human mind. Yet for simpler creatures with no significant brain at all, its tenets still serve us well and have sunk in so deep as to no longer be thought a distinct "ism" from the rest of animal biology. Where do we draw the line?
Our inner life is deeply connected to the information our cognitive bran structures process. Indeed, there is a growing view that "consciousness is what information feels like to itself when it reaches a certain level of complexity". Cognitive behaviours are defined precisely by the existence of such information processing going on in the background. Yet there are signs that even in the human brain, much of this processing goes on at an unconscious level, with our consciousness being informed of the outcome anything up to a second or so after the event.
One must assume that much of the manta ray's cognitive processing is similarly unconscious. But is there a sentient consciousness in there, an experiential awareness of the outcome? The human brain has identifiable "consciousness circuitry" forming large parts of its outer cortex. We may assume that any creature whose brain exhibits similar structures must also be supporting similar subjective experiences. The manta ray does not have such highly evolved structures as ours, but that does not necessarily mean that it does not have sufficient for sentience.
Cognition is not just about receiving and processing sense imporessions from your environment, but about understanding what those impressions are telling you and modifying your behaviour accordingly. Freckles' behaviour can only be explained if she has some cognitive model of the world around her and some ability to think her way round problems. She unmistakably knew what she was doing. And she knew that she wanted those fish hooks gone. That combination of pain, understanding and flexible or general intelligence can only be explained as a sentient consciousness.
At least some species of octopus are also known to be sentient like ourselves. Since the days of our last common ancestor, probably a humble flatworm with a nominal nerve chord along its body, the physiology of the octopus has evolved entirely separately from ours. Not only is it eight-armed and boneless but it has three hearts with blue blood running through its veins. Its eyes have the light-sensitive retina in front of all the supporting nerve fibres and blood vessels; the opposite way round to ours and a far more efficient arrangement. Its nerves and brains are similarly alien – the nerve fibres are much thicker than ours and lack a myelin sheath, it has eight separate brains for each tentacle and a ninth wrapped round its digestive tract.
Yet under close examination the central brain is found to have evolved a thinking cortex – an area known to be linked to consciousness – that comprises exactly the same network of cross-linked nerve columns (like the ratlines of an old sailing ship) as does our own; its brain has all the necessary features for consciousness. Moreover its behaviour displays advanced cognition. The common octopus even appears to dream in its sleep; like us it alternates between two sleep modes, one quiescent and one active in which its eyes move, its arms twitch and suckers contract, and it changes skin colour and texture. This corresponds closely to our REM mode of sleep, which is when we have most of our dreams.[2]
Professor of Marine Biology David Scheel took an example of a species known as the day octopus home. The octopus, called Heidi, solved complex puzzles, recognised individual humans, gooshed them up the arm or activated a light outside its tank for attention, even swam over to the side of the tank, bugged out its eyes and watched TV with the rest of the family.[3] What sensations does such an alien mind experience? What subjective qualities do those sensations possess?
Craig Foster struck up a similar relationship with a wild octopus, befriending it over much of its life. He found a remarkable amount of common ground.[4] This provides evidence that even brains evolved with quite different physiologies and anatomies will, when it comes to intelligence and sentience, display a degree of convergent evolution. This in turn suggests that, at the information processing level, there is only one way to do intelligence and sentience.
The Cambridge Declaration on Consciousness already acknowledges the octopus among our cognitive cousins when it states:[5]
“The absence of a neocortex does not appear to preclude an organism from experiencing affective states. Convergent evidence indicates that non-human animals have the neuroanatomical, neurochemical, and neurophysiological substrates of conscious states along with the capacity to exhibit intentional behaviors. Consequently, the weight of evidence indicates that humans are not unique in possessing the neurological substrates that generate consciousness. Non-human animals, including all mammals and birds, and many other creatures, including octopuses, also possess these neurological substrates.”
Birds shown to have exhibited suitably high-level cognition include several species each of the parrot and corvid (crow) families. Besides the octopus, I am not sure whether its relatives the squid and nautilus share those same neurological substrates. I should love to know too whether Freckles has the equivalent. But whether she does or not, we now know of at least four separate evolutionary lineages to sentience, Wow! That strongly suggests that wherever animal-like life arises, in due course sentient beings will apear.
The manta ray is merely the latest in a long list of creatures with brains large and complex enough to demonstrate advanced cognitive and mental abilities. And what a way to make its entrance!
And where do we draw the line? If a species shows a mere residual cognition, is there necessarily some sentient consciousness accompanying it? Even the bee, one of the more intelligent insects, is beginning to raise such questions. It has more of a nerve complex than a real brain, but its behaviour is proving more sophisticated than hitherto suspected and is increasingly being described in the language of cognition. What information might lurk within those patterns of nervous activity? Perhaps one day we shall find out.
Science is finally beginning to admit what has been so obvious to so many of us for so long; it is beginning to learn and document for itself just how full of inner experience the animal kingdom must really be.[6] The stories of Freckles and Heidi are a real wake-up call. Moralists, neurologists, psychologists, philosophers and computer scientists can no longer get away with assuming that all animals are "dumb". Society can no longer stumble on in the belief that abuse of individual animals is as acceptable as the abuse of individual plants.
It is harder to say "stop fishing" or "go vegetarian", for pain, mayhem and death are inevitable accompaniments to the sentient circle of life. Few creatures outside of human captivity have ever died of old age. But let us at least be honest about it and as sensitive and humane as possible.