The understanding that even bees have feelings is changing our view of consciousness

I recently discovered some scientific research that struck me to the core. I have spent many years exploring biology and the interconnectedness of life. Yet here was something that cut through all the knowledge I thought I had acquired: scientists have found that if male fruit flies are deprived of sex with females, they turn to alcohol. I immediately headed to the kitchen – not for a drink, but to watch some fruit flies I had seen earlier around a slice of lime my daughter had failed to clear away.

I took my hand lens, carefully snuck close to a Drosophila and peered into its red, mosaicked eye. We might be separated in evolutionary time by some 780 million years, I thought, but we share fundamental similarities. Natural selection has equipped us both with a brain that functions to improve our survival and that of our offspring. Is this why both flies and humans, on occasion, seek to douse flames of sexual rejection with alcohol? Just because flies don’t write poetry about it doesn’t mean they don’t experience a rich inner life.

My encounter with the fruit fly in the kitchen led me on a mission to understand the feelings experienced by other animals, including insects – to explore from a non-human point of view what it means to be conscious. Only a few decades ago, it was scientific taboo to suggest that even chimpanzees had personalities or feelings. Now, evidence of complex inner worlds in a wide range of non-human animals is mounting. Even “simple” animals make a good case. Fish seem to know themselves. Bees can be pessimistic. Cuttlefish plan for the future.

This is serious stuff, and it is incumbent on us to understand the extent of animal consciousness so that we can treat our fellow organisms with the respect they deserve. But the quest also sheds light on how this most murky and mysterious of attributes evolved, and what it actually means.

The big question is around what philosophers call phenomenological consciousness: having a subjective view of the world. The aptly named “hard problem” of consciousness is to explain not only why we have feelings at all, but to describe the physical basis of that subjective sense. Examining the lives of non-human animals can help tackle this notoriously difficult problem, says philosopher Tim Bayne at Monash University in Melbourne. “If we assume there is a kind of subjective experience in an animal,” he says, “what might it be like? What reason would it have to be conscious?”

I turn to Lars Chittka, a behavioural ecologist at Queen Mary University of London. His team’s work has shown that bumblebees engage in what can best be described as play. Chittka made a mini ball pit near the bees’ nest and found that the insects rolled the balls for extended periods. Not only that, but they seemed to enjoy it, going out of their way to go back to the play area. “It looks like subjective experience. It looks likely they are having emotion-like states,” he says.

Other insects seem to engage in play, too. Last year, researchers made an insect amusement park and found that some fruit flies sought out rides on a spinning carousel. Play is fun, but it has a function. In this case, perhaps the spinning motion helps the flies learn self-perception to fly and navigate better.

I asked Chittka about the haunting finding that male fruit flies drink alcohol if they can’t have sex. Flies that had recently mated and those that were prevented from doing so were both offered either regular food or food laced with 15 per cent ethanol. The sexually satisfied males ate both types equally, while the thwarted males strongly preferred the booze. The scientists also identified a neural system that links the rejection to the alcoholic reward. “For me, the observation that if you deprive male fruit flies of the opportunity to have sex, they turn to something that likely makes them feel better, it is highly suggestive that they are experiencing a negative feeling [that] can be remedied with a drug, in this case alcohol,” says Chittka.

You might object and say that neither play nor self-medication with alcohol is evidence of consciousness. Yet, to many scientists, the findings suggest there is a subjective sense of self held by these animals.

“I don’t know how to prove if another individual is conscious, even with humans,” says psychologist Nicola Clayton at the University of Cambridge. But she has tried to probe several animals’ subjective experiences. In one experiment, her team performed a version of the famous marshmallow test on cuttlefish, testing to see what the creatures would do when offered a choice between one treat (a live shrimp) immediately or two if they waited. Like some children, cuttlefish were able to delay gratification. “It’s an important part of planning for the future,” says Clayton. “I would say that’s good converging evidence that this animal has consciousness.”

A few years ago, when I visited Clayton’s aviary in Cambridge, I experienced something I can’t explain without endowing birds with consciousness. The aviary housed four or five young jays and, as Clayton opened the door and we entered, the birds first came to see her, but then, on seeing me, a stranger, they ran behind a nest box as if to hide. The birds started vocalising – it sounded like they were saying: “sorry – sorry!” I looked to Clayton in astonishment. “They are apologising for running away. It’s because they don’t know you,” she said.

This instinctive interpretation may be hard to prove, but Clayton and her colleagues have shown that jays can relive past moments and anticipate future ones. In one 2024 experiment, food was hidden under one of a line of distinctive cups. The watching jay was then removed while the order of the cups was shuffled. When the bird returned to the test chamber 10 minutes later, it could remember the correct cup. This is good evidence for episodic memory – long-term, event-based memory – and is evident in the wild: jays have evolved to cache food and retrieve it later, and adjust their behaviour to deceive others if they are being watched.

As I assimilate this new thinking on animal consciousness, I find myself moving through the world in a different way. I notice some honeybees landing on cyclamen flowers, and watch the bees carefully for signs of caution. Chittka has shown that if bees encounter crab spiders lurking in flowers, they become nervous when visiting other plants.

That makes sense, because crab spiders are dangerous predators of bees. “Their demeanour changes – they fly slower,” says Chittka, “but false alarms happen.” They will sometimes check out a flower that has no predator, yet still reject it. “It’s as if they’ve seen a ghost,” says Chittka. “Anthropomorphically speaking, it’s like we see in PTSD when people conjure up a threat of something not there.”

Bees aren’t the only seemingly simple creatures with signs of consciousness: the more experiments scientists conduct, the more they uncover animals with complex inner lives. Magpies are one of a growing number of species to have passed the mirror test, and were the first non-mammals shown to do so. This test aims to assess whether an animal has a sense of self based on its interaction with its own reflection. Perhaps it’s not too surprising that a magpie can do this, but more startling is the finding that a fish – the cleaner wrasse – has also passed the mirror test.

Will Sowersby at the Arthur Rylah Institute in Australia and his colleagues noted the speed and ease with which cleaner wrasse habituated to a mirror in their tank and started using it to inspect their own bodies. But then they saw a fish take a piece of shrimp, drop it in front of the mirror, and watch it fall in the reflection. It was as if the fish was a kind of physicist, performing an experiment. “What we were seeing is evidence that an animal can undertake hypothesis testing,” says Sowersby. “The cleaner fish used a piece of shrimp to test the properties of the mirror. A remarkable observation.”

Sowersby’s colleague Shumpei Sogawa at Osaka Metropolitan University in Japan is more measured. “What is particularly striking,” he says, “is that such behaviour can look extraordinary to us because we tend to underestimate what fish normally do.”

Amid the various tests, animals’ ability to learn from experience is increasingly considered one of the most important signifiers of consciousness. Jonathan Birch, a philosopher at the London School of Economics, has been working with neurobiologist Simona Ginsburg and geneticist Eva Jablonka on a framework they call unlimited associative learning, or UAL. To evaluate consciousness, they propose measuring five aspects of an animal’s capacity to learn.

One important aspect is the ability to learn to associate one stimulus with a second, novel stimulus. The classic example is Pavlov’s dogs: the canines learn to associate a bell with food, then they salivate at just the sound of the bell. Fruit flies and honeybees can do this, so these animals, and dogs, tick that box in the UAL checklist. This sophisticated learning reflects animals’ consciousness, says Birch. “Animals are not just calculators. They don’t just solve puzzles. They also have emotions. They have inner lives in which they feel things, and we can make inferences about these things as well.”

Birch, Ginsburg and Jablonka have combed through the scientific literature to build the case for UAL, and therefore consciousness, in a range of animals. Their work suggests consciousness independently evolved at least three times, says Birch: in vertebrates, where it led to consciousness in birds and mammals; in cephalopod molluscs, where it led to sentient octopuses and cuttlefish; and in arthropods, which created conscious insects, spiders and crustaceans, such as lobsters. “In at least those three lineages, they’ve gone from a non-conscious starting point to having a form of consciousness,” says Birch.

What we are learning from animals helps sharpen the thinking on why consciousness evolved, says Bayne. “The basic purpose of consciousness is to alert you to critical bodily needs: do I need food? Am I too hot? Am I too cold? Am I in danger? Is this a mating opportunity?” he says. If the purpose of consciousness is to address those variables, then it makes sense why bodily sensations like thirst are so vivid and salient, and so central to consciousness.

The advantage of UAL is that it doesn’t get bogged down in some bigger grand theory for the mind, such as integrated information theory or global workspace theory. “You say, ‘I don’t care about theories of consciousness. I’m just going to look for behavioural and neural signatures of consciousness and see if they’re similar to what happens in humans,’” says Anil Seth at the University of Sussex, UK.

These approaches avoid directly trying to answer the hard problem of why a physical process is accompanied by a conscious feeling. “I don’t think we make the best progress by going after the hard problem directly,” says Seth. “I think we go after it indirectly, and this is one way of doing that.”

“We don’t need to solve the hard problem to have evidence of consciousness in other systems,” says Birch. “Indeed, it might lead over the longer term to better solutions, because the more evidence you have, the better position you’re in to develop theories about the nature of consciousness.”

These recent discoveries in animals raise some serious questions about welfare. “What I hope is that the growing awareness of there being a kind of inner life in many animals, including invertebrates like octopuses, does lead to changes in the way people treat them,” says Birch. We have seen this in the opposition to octopus farming. “People have seen [that] octopuses are these amazing beings with rich mental lives,” he says. “It’s inappropriate to pack 20 or 30 of them into tiny spaces.”

The key question for whether we have a right to exploit an animal, says philosopher Simon Brown at Ashoka University in Sonipat, India, is “whether they have genuine interests where you can do things that matter to them, in the sense that they have a perspective from which certain things are good or bad for them”.

It seems there is a strong case that insects, spiders, lobsters and crabs, as well as fish, cephalopods and all vertebrates, have this self-perspective. Insects such as crickets and black soldier flies are raised in their billions to be processed for food, mainly for animals, with next to no thought for their inner lives. “They are killed by microwave,” says Chittka. “We can do better, though, and minimise suffering.”

I thought back to my close encounter with the fruit fly in the kitchen. Insect compound eyes are constructed such that a black dot called a pseudopupil can appear when you look at the eye head-on. This had the unsettling effect, when I peered at it with my lens, of making it seem like the fly was gazing intently into my eye. Drosophila has been the subject of countless experiments. As well as hitting the booze, males prevented from mating exhibit various responses, such as enhanced aggression, that scientists describe as “frustrative-like”. This can’t help but give you an insight into what it is like to be a fly.

“Knowing that about Drosophila changes, at some level, your appreciation of the kind of thing it is, and gives you access to it,” says Bayne. “Many people would take very seriously the idea that insects are conscious.”

Billions of individual flies, maybe trillions, have been bred and investigated and mutated, with little or no regard for their welfare. This sends a shudder through me, and I hope it does you, too. And even with an awareness of the danger of anthropomorphising them – male fruit flies aren’t like men in their taste for alcohol – it is hard to deny that there is something wonderful and unifying about what we are learning about the feelings and inner lives of our fellow creatures.