Insects and Other Animals Have Consciousness, Experts Declare
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Welcome to the Quanta Science Podcast. Each episode we bring you stories about developments in science and mathematics. I'm Susan Vallett. A group of prominent biologists and philosophers announced a new consensus: there's a realistic possibility that insects, octopuses, crustaceans, fish, and other overlooked animals experience consciousness. That's next.

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In 2022, researchers at the Bee Sensory and Behavioral Ecology Lab at Queen Mary University of London observed bumblebees doing something remarkable. The diminutive, fuzzy creatures were engaging in activity that could only be described as play.

Given small wooden balls, the bees pushed them around and rotated them. The behavior had no obvious connection to mating or survival, nor was it rewarded by the scientists. It was, apparently, just for fun.

The study on playful bees is part of a body of research that a group of prominent scholars of animal minds cite, buttressing a recent declaration that extends scientific support for consciousness to a wider suite of animals than has been formally acknowledged before.

For decades, there's been a broad agreement among scientists that animals similar to us, the great apes for example, have conscious experience, even if their consciousness differs from our own. But in recent years, researchers have begun to acknowledge that consciousness may also be widespread among animals that are very different from us, including invertebrates with completely different and far simpler nervous systems.

The April of 2024 Declaration, signed by biologists and philosophers, formally embraces that view. It reads, in part, The empirical evidence indicates at least a realistic possibility of conscious experience in all vertebrates, including all reptiles, amphibians, and fishes, and many invertebrates, including, at minimum, cephalopod mollusks, decapod crustaceans, and insects."

The document is inspired by recent research findings that describe complex cognitive behaviors in these and other animals. It represents a new consensus and suggests that researchers may have overestimated the degree of neural complexity required for consciousness.

The four-paragraph New York Declaration on Animal Consciousness was spearheaded by philosopher and cognitive scientist Kristen Andrews of York University in Ontario, philosopher and environmental scientist Jeff Sebo of New York University, and philosopher Jonathan Birch of the London School of Economics and Political Science. It's been signed by more than 280 researchers.

The Declaration focuses on the most basic kind of consciousness, known as phenomenal consciousness. Roughly put, if a creature has phenomenal consciousness, then it is like something to be that creature, an idea enunciated by philosopher Thomas Nagel in his influential 1974 essay, "What is it like to be a bat?"

Even if a creature is very different from us, Nagel wrote, fundamentally an organism has conscious mental states if and only if there is something that it is like to be that organism. We may call this the subjective character of experience. If a creature is phenomenally conscious, it has the capacity to experience feelings such as pain or pleasure or hunger, but not necessarily more complex mental states such as self-awareness.

Neuroscientist Anil Seth, who signed the declaration, says he hopes it draws greater attention to the issues of non-human consciousness and to the ethical challenges that come with that idea. Seth, who's based at the University of Sussex, says he hopes the declaration sparks discussion and informs policy and practice in animal welfare. He says it galvanizes an understanding and appreciation that we have more in common with other animals than we do with things like chat GPT.

The declaration began to take shape last fall, following conversations between SIBO, Andrews, and Birch. Here's SIBO. The three of us were talking about how much has happened over the past 10 years, past 15 years in the science of animal consciousness. And my perspective has been that a lot of people, especially advocates, policymakers, other changemakers, a lot of people are dimly aware that

that a lot of exciting progress has been made in this field. And in particular, that scientists are gathering more evidence that possibly invertebrate species are conscious and capable of pleasure and pain and happiness and suffering. But nobody knows where to look to find a clear, concise statement endorsed by a lot of people that expresses where this field is currently at.

We now know, for example, that octopuses feel pain and cuttlefish remember details of specific past events. Studies in fish have found that cleaner wrasse appear to pass a version of the mirror test, which indicates a degree of self-recognition, and that zebrafish show signs of curiosity. In the insect world, bees show apparent play behavior, while some fruit flies have distinct sleep patterns influenced by their social environment.

Meanwhile, crayfish display anxiety-like states, and those states can be altered by anti-anxiety drugs. These and other signs of conscious states in animals that had long been considered less than conscious excited and challenged biologists, cognitive scientists, and philosophers of mind. Here's Sebo again. A lot of people have now accepted for a while that, for example, mammals and birds are

are either conscious or very likely to be conscious, but less attention has been paid to other vertebrate, especially invertebrate taxa. In conversations and at meetings, experts largely agreed that these animals must have consciousness. However, this newly formed consensus wasn't being communicated to the wider public, including other scientists and policymakers.

So the three researchers decided to draft a clear, concise statement and circulate it among their colleagues for endorsement, says Sebo. Not, of course, to be in any way comprehensive, but to point to where we think the field is now and where the field is headed and to indicate that there, as we say in the Declaration, is at least a realistic chance of consciousness in all vertebrates and many invertebrates and that this is reason enough for welfare risks to be considered in policymaking. The Deck

The Declaration updates the most recent effort to establish scientific consensus on animal consciousness. In 2012, researchers published the Cambridge Declaration on Consciousness, which said that an array of non-human animals, including but not limited to mammals and birds, have the capacity to exhibit intentional behaviors, and that humans are not unique in possessing the neurological substrates that generate consciousness.

Seth says the latest declaration expands the scope of its predecessor and is also worded more carefully. He says it emphasizes what we should take seriously regarding animal consciousness and the relevant ethics given the evidence and theories that we have. Seth says he's not in favor of avalanches of open letters and the like, but he ultimately came to the conclusion that this declaration was very much worth supporting.

Peter Godfrey Smith, a philosopher of science at the University of Sydney, who has worked extensively with octopuses, believes that the complex behaviors those creatures exhibit, including problem solving, tool use, and play behavior, can only be interpreted as indicators of consciousness. Encephalopods, in many cases, generally, they've got this attentive engagement with things and with us and with novel objects that make it very hard not to think that there's

quite a lot going on inside them. It just seemed like a natural inference to draw. Now, then you have to be critical and ask yourself, is this misleading? Might we find out things later on that show that this was all an illusion? And the way things have proceeded has definitely not been along those deflationary lines. I think in the case of octopuses, the first impression of a kind of conscious engagement with their world is

looks more and more like a reasonable impression. Godfrey Smith points to recent papers looking at pain and dreamlike states in octopuses and cuttlefish. Which are extremely intriguing. Octopuses, along with a lot of other animals, have several phases of sleep, quiet sleep and active sleep, in the way that humans have slow wave and REM sleep. They have all these different things. The pain work and the dream work are very different, but they

to some extent do point in the same direction towards there being a lot going on, towards experience as being a real part of their lives. While many of the animals mentioned in the declaration have brains and nervous systems that are very different from those of humans, the researchers say that this needn't be a barrier to consciousness. For example, a bee's brain contains only about a million neurons compared to some 86 billion in the case of humans.

But each of those B neurons may be as structurally complex as an oak tree. The network of connections they form is also incredibly dense, with each neuron contacting perhaps 10,000 or 100,000 others. By contrast, the nervous system of an octopus is complex in other ways. Its organization is highly distributed rather than centralized. A severed arm can exhibit many of the behaviors of the intact animal.

philosopher and cognitive scientist Kristen Andrews says there's an upshot. Kristen Andrews: What we are learning is that not as much as we used to think is going to be necessary. So one of the things people often have written in the past is like, well, the nematode worm can't be conscious because it only has 300 and some neurons. And so it seems just implausible that such a thing could be conscious.

But I think people are coming to the realization, like, we don't know why, like how many neurons would be necessary, you know, the C. elegans are able to integrate information in their neural ring, and make decisions based on multimodal perceptual stimuli. This is recent science that's come out about nematode worm neurophysiology. And that sounds like you can do a lot of it, you can

integrate information with 300 and whatever it is neurons in the nematode worm.

So we might not need nearly as much equipment as we thought we did. Andrews points out that even a cerebral cortex, the outer layer of the mammalian brain, which is believed to play a role in attention, perception, memory, and other key aspects of consciousness, may not be necessary for the simpler phenomenal consciousness targeted in the Declaration. There was a big debate about whether fish are conscious.

And a lot of that had to do with them lacking the brain structures that we see in mammals. But when you look at birds and reptiles and amphibians, they have very different brain structures and different evolutionary pressures. And yet some of those brain structures we're finding are doing the same kind of work that a cerebral cortex does in humans. And then we don't even know if the cerebral cortex is involved in conscious experience. There's so many different theories about what parts of the brain are involved. Godfrey Smith agrees. But the architecture...

does not have to be one way or the other. You don't have to have a vertebrate-like architecture to have at least all these experience-relevant looking behaviours, you know, these pain-like behaviours, these dream-like behaviours,

All of those can exist in an architecture that looks completely alien to a vertebrate or human architecture. Andrew says the approach being taken in philosophy and science is recognizing that none of our theories of consciousness are secure. And some researchers are working within the framework of a theory to see if they can provide evidence for or against it.

But they recognize at the same time the theory is not secure. So we're not going to be able to answer questions like what parts of the brain are necessary for consciousness until we make some progress on developing a secure theory of consciousness. While the Declaration has implications for the treatment of animals, and especially for the prevention of animal suffering, philosophers

and environmental scientist Jeff Sebo says the focus should go beyond pain. If we do want to treat, for example, animals in captivity well, then we need to do more than prevent them from experiencing bodily pain and suffering. We also have to provide them with

the kinds of enrichment and opportunities that allow them to express their instincts and explore their environments and engage in social systems and otherwise be the kinds of complex agents they are. And so this research really fills out that picture and shows us not only how sophisticated their minds are, but

also how many different issues we would need to think about in order to care for them properly. But the consequences of bestowing the label of conscious onto a wider array of animals aren't straightforward.

particularly with regards to animals whose interests we're not used to considering. Godfrey Smith points to a pesky example. The relationship we have with insects as humans, it's in many cases inevitably a somewhat antagonistic one. I mean, they eat crops, they do all sorts of stuff. Mosquitoes are a huge problem for human well-being, especially in tropical parts of the world.

So, the idea that we could just sort of make peace with the mosquitoes, I think is, it's a very different thought than the idea that we could make peace with the fish and the octopuses and the others. Similarly, little attention is given to the well-being of insects, such as certain fruit flies widely used in biology research.

Matilda Gibbons researches the neural basis of consciousness at the University of Pennsylvania and has signed the declaration. "I'm not saying that the whole world needs to change and we need to like care about every single ant we step on and stuff. I'm not necessarily saying that. I'm just saying that we think about the welfare of livestock and mice in research, but we never think about the welfare of the insects." While scientific bodies have created some standards for the treatment of lab mice, it

It's not clear if the declaration will lead to new standards for the treatment of insects. But new scientific findings do sometimes spark new policies. For example, Britain enacted legislation to increase protection for octopuses, crabs, and lobsters after a London School of Economics report indicated that those animals can experience pain, distress, or harm.

While the declaration makes no mention of artificial intelligence, the issue of possible AI consciousness has been on the minds of animal consciousness researchers. Here's Sibo. I think current AI systems are very unlikely to be conscious, but it does give me pause and make me want to approach the topic with caution and humility and the same kind of rigorous systematic analysis.

that researchers are now using for the study of animal consciousness. I think instead of simply asserting or dismissing that AI systems are conscious, we need to

look to existing scientific theories of consciousness and identify behavioral and architectural features, indicators, or proxies of consciousness that can be applicable to AI systems, and then really go look at those AI systems and use the best evidence available to try to make rough estimates about the probability that there might be consciousness according to certain theories. Andrews hopes that the declaration will spark more research into animals that have often been overlooked.

a move that has the potential to further expand our awareness of the scope of consciousness in the animal world. I'm proposing a methodology that I think will help us make progress on a theory. And that methodology is study a wider array of subjects, especially focus your attention on simpler subjects. All these nematode worms and fruit flies that are in almost every university,

Study consciousness in them. You already have them. Somebody in your lab is going to need a project. Make that project be a consciousness project. Imagine that. That would be cool.

Arlene Santana helped with this episode. I'm Susan Vallett. For more on this story, read Dan Falk's full article, Insects and Other Animals Have Consciousness, Experts Declare, on our website, quantamagazine.org. Make sure to tell your friends about the Quanta Science Podcast and give us a positive review or follow where you listen. It helps people find this podcast.