Back in 2008, a miniature mystery unfolded at Sea Star Aquarium in Coburg, Germany. Staff turned up for work in the morning to find the aquarium was eerily silent and dark. It transpired that the entire building’s electrical system had short-circuited. The technical difficulties were fixed until the problem was reported the following morning. And again the day after.
Sensing something was off, a few staff members decided to spend the night at the aquarium and stake out the situation, but nothing untoward was seen. It wasn’t until one morning when the director of the aquarium, Elfriede Kummer, turned on the lights and saw their resident octopus, six-month-old Otto, had climbed to the edge of his tank and was spitting water at the bright spotlight above his tank.
For whatever reason – perhaps out of annoyance, perhaps boredom, maybe just for fun – Otto had taken issue with the equipment and found an ingenious way to turn it off.
There’s always a risk of anthropomorphizing behavior like this, but it’s hard to deny that Otto the octopus was displaying the behavior of a calculating and highly intelligent individual. Could this act of mischief even be the expression of a truly sentient being? It seems very likely.
Sentience is a tricky concept to define, yet it has a profound importance for how we interact with other living things (and perhaps even things we should consider non-living).
“There are lots of ways we could define sentience, and some of those ways end up trivializing it and losing sight of why it’s important,” Dr Jonathan Birch – a world-leading expert on sentience and an Associate Professor at the London School of Economics and Political Science’s Department of Philosophy, Logic, and Scientific Method – told IFLScience.
“If we just defined it as responding to stimuli, then it’s very easy to achieve, but also not very important ethically. What we’re looking for is an ethically significant experience,” he continues.
“To me, it’s very closely linked to the capacity to suffer, to the capacity for pleasure or pain. But I think it would be a little bit too narrow to define sentience as just the capacity for pleasure or pain, because we care about other aspects of mental life as well, in states like boredom, anxiety, joy, and comfort. These are all ethically significant experiences as well.”
It’s not hard for humans to feel a sense of sentience in some animals, especially if they share similarities with us. Chimpanzees and other great apes are the most obvious examples, but many people would argue that dogs, cats, and other household pets are complex individuals with a strong capacity to love and suffer.
Things are a lot messier when we try to recognize sentience in invertebrates, such as octopuses, which bear very few similarities to us on the surface.
Although evidently capable of high levels of cognition, the octopus brain is radically different from any mammal or vertebrate animal. It features a vertical lobe, which plays a key role in learning, memory, and problem-solving – the complex functions that are typically associated with the cortex in the human brain.
However, most of the neurons of an octopus are distributed throughout its eight arms, rather than its brain. These networks of neurons can act somewhat independently – even coordinating with each other – in the absence of input from the central brain (although the arms don’t have minds of their own).
When we consider the vastly different hardware for perceiving reality that octopuses and humans possess, it’s almost impossible for us to imagine how octopuses must experience the world around them.
“When we’re confronted with an octopus, separated from them by over 500 million years of evolution, they seem very alien. The brain organization is very, very different. It’s quite likely that they’ve evolved their own form of sentience by a very different route, just as they’ve evolved their own form of eyes by a very different route,” Birch explained.
“We don’t really know how accurate human terms like ‘pain’ or ‘pleasure’ are in the case of the octopus, but we have every reason to think there’s some sentience of some kind there – and that’s enough, I think,” he notes.
Perhaps brain structure is not the most useful to approach this predicament. A huge amount of significance is placed on the neocortex of humans, a relatively recently evolved structure that’s often attributed to our “higher cognitive functions” such as language, personality traits, emotion processing, and more.
Given its “advanced” qualities, some argue that the neocortex may be the physical seat of consciousness in the brain, while others argue that it’s likely to be just one part of the puzzle.
“You’ve got a whole group of theorists who say the importance of the cortex has been exaggerated and that it’s really more of a graphics card than a CPU, as it were,” Birch notes.
“It greatly enriches the content of our experiences. It gives us the full Technicolor of our ordinary conscious state. But that if you lost it, you’d still be sentient,” he explains.
Birch was the lead author of a 2021 report for the UK Government that explored whether cephalopods, like octopus and cuttlefish (as well as decapod crustaceans, like crabs and lobsters) could be considered sentient beings.
The conclusion was yes – well, probably yes – and, in response to Birch’s report, the UK’s Animal Welfare Act 2006 was amended to include octopus, crabs, and lobsters.
We say “probably yes” because sentience can be extremely awkward to prove with utter certainty, at least with our current understanding of consciousness and the vocabulary to explain it. Simply put, we don’t even have a strong grasp of how the human brain works, let alone other lifeforms with vastly different neural equipment.
“You have to err on the side of caution because you aren’t certain. You don’t you don’t know if the animals are feeling anything, but you recognize a risk that it might be,” Birch notes.
It isn’t just animals we have to worry about when it comes to the possibility of sentience. Along with human fetuses and “mini-brain” organoids in a test tube, there are the fiddly cases of people in comas or so-called “vegetative states.”
Moreover, it’s likely that humanity will soon have to grapple with the question of whether artificial intelligence (AI) possesses some level of sentience. René Descartes proposed that “language is the only certain sign of thought hidden in a body,” but large language models like ChatGPT are already challenging that idea.
“We can’t just see it as a sci-fi possibility anymore,” said Birch.
“The markers [of sentience] we look for in animals – behavior, how they react to stimuli, things like that – have no application to an AI that is a disembodied system with no biological brain at all. At the same time, we can’t just assume that because there’s no biological brain, there’s no possibility of sentience,” he added.
Many of these ideas are explored in Birch’s latest book – The Edge of Sentience: Risk and Precaution in Humans, Other Animals, and AI – which is available to read for free online.
Despite the heaps of uncertainty that laden the topic, Birch’s central argument is that we need to start developing an evidence-based approach to grapple with the concept of sentience before it’s too late. Until we have clear answers, it’s an issue we must approach with the utmost caution and care.
“It’s just an incredibly difficult problem that the science of consciousness is not yet mature enough to solve,” concluded Birch.
