The Surprisingly Sophisticated Mind Of An Insect

Insects appear to be more intelligent and emotionally complex than we give them credit for. Perhaps, new research suggests, they are even conscious.


Sandro Rybak for Noema Magazine

Carrie Arnold is a freelance health and science writer living in Virginia.

At the age of 20, I committed my first mass murder. I didn’t, of course, mean to. But my good intentions meant nothing to the small mound of deceased fruit flies in the bottom of the vial.

My goal was simply to anesthetize them and then search their wrinkled, vellum wings and bulging eyes for mutations. It was a classic introductory genetics experiment, one taught to countless aspiring biologists for a century. I doused a cotton ball with ether, the fruity-smelling liquid that would render the flies temporarily unconscious (and easier to count). The instructor warned us to make sure the flies were completely knocked out, so they didn’t wake up mid-experiment. So I left the ether-soaked cotton on the vial an extra minute or two. Just to be safe.

It wasn’t the first time I killed an animal in the name of science. I dissected a fetal pig in a high school biology class. I massacred bacteria by the billions as a student research technician and budding microbiologist. The only twinge of guilt I felt when dissecting worms as a 12-year-old was when my mom served spaghetti with meat sauce for dinner, and the noodles on my plate looked all too similar to the slimy earthworms I had earlier dispatched to Valhalla with a scalpel. 

And so I told myself that the flies had lived a good life, with plenty of overripe bananas and opportunities to swipe right on Drosophila Tinder. They died for a good cause. 

I’m not heartless. Had I accidentally gassed several dozen kittens, I would have yeeted myself off the nearest building, overcome with guilt. These were flies. It was no big deal.

Most biologists would agree with me. “When I started studying bees in the late 1980s, the prevailing view was not just that they’re not conscious, but that they are just incapable of any kind of emotion,” Lars Chittka, a sensory and behavioral ecologist at Queen Mary University of London, told me recently. “The whole notion would have seemed just absurd.”

However, a growing collection of new experiments is challenging the old consensus. Far from being six-legged automatons, they can experience feelings akin to pain and suffering, joy and desire. When Chittka gave bumblebees an extra jolt of sucrose, their favorite food, the bees buzzed with delight. Agitated, anxious honeybees, on the other hand, responded with pessimism when researchers shook them to simulate a predatory attack. Other researchers found that they “scream” when under threat. Ants display rudimentary counting abilities, can understand the concept of zero and make tools. Fruit flies learn from their peers. Cockroaches have complex social lives. Fruit flies drown themselves in booze when deprived of mating opportunities. Some earwigs and other insects play dead when threatened by a predator.

In other words, insects have thoughts and feelings. The next question for philosophers and scientists alike is: Do they have consciousness?

Nearly 400 years ago, the French philosopher and polymath René Descartes formulated a devastatingly simple answer to the question, “What is consciousness?” Cogito, ergo sum —I think, therefore I am. Hidden in that three-word Latin phrase is the assumption that humans are the only thinking animals. No matter how emphatically you ask a monkey or a snail whether they are alive and conscious, they will never answer. As the only species endowed by God with a soul and rational mind, humans, Descartes believed, sat at the summit of all life on Earth.

Cutting-edge research over the last few years has begun to shift this view. 

“Humans are no longer seen as at the pinnacle of creation,” Catherine Wilson, a philosophy fellow at the Institute for Advanced Study in Berlin, told me. “There’s a greater modesty and awareness in which we are just one species — and maybe not even the most important species.”

To Wilson, the biological basis of consciousness arises from the separation of self from the world. “Animals need to know what their movements are and what is happening in the world,” she said. That gives rise to an experience, which is the fundamental building block of consciousness. It’s an idea that builds on a 1974 essay by the philosopher Thomas Nagel, who tried to answer the question of consciousness by asking: “What is it like to be a bat?” Unlike most humans, who move through the world guided mostly by sight, many bats are nearly blind and navigate by sound. And while many of us may have imagined life as a bat, only bats can know what it’s like to be a bat.

“Cockroaches have complex social lives.”

“Yet if I try to imagine this, I am restricted to the resources of my own mind, and those resources are inadequate to the task,” Nagel wrote. “I cannot perform it either by imagining additions to my present experience, or by imagining segments gradually subtracted from it, or by imagining some combination of additions, subtractions and modifications.”

If any creature has a sense of what it’s like to be that creature, Nagel’s argument goes, it’s conscious. Whether we humans can understand what it’s like is beside the point. As I was re-reading Nagel’s essay recently, a group of cardinals alit on the bird feeder outside my office window. My cat perched on the sill, ears forward like furry satellite dishes, her tail swishing in preparation for a pounce. She even called out to them, a raspy chirp of eckeckeckeckeck.

My cat almost certainly has a sense of what it’s like to be a cat, and a bat has that same sense for itself, but do flies and other insects? And if they do have this sense, where does it come from? 

Whereas Descartes could claim that human consciousness was a gift of the divine, modern scientists and philosophers don’t treat consciousness as if it were miraculously bestowed upon the world, all neatly tied up with a big red bow. Consciousness, then, is a natural phenomenon, not a religious one. 

That meant consciousness had to have a biological explanation. That explanation immediately focused on the brain. To Descartes and like-minded philosophers, consciousness is inextricably linked to the human mind. 

“It’s all about the cortex,” Christopher Hill, a philosopher at Brown University, told me. The cortex is the brain’s folded, wrinkly cap — what science communicator Ze Frank calls “the thinky thinky parts.” The swollen cortex of a person controls many of the features that we typically consider make us human: things like rational thought, awareness and language. If consciousness were a purely human phenomenon, then its origination in the cortex makes sense. The human cortex is so much bigger than other species’ that it’s part of what makes Homo sapiens neurologically special. 

Despite their reputation as mindless automatons, insects have three blobs of neural tissue that, taken together, form a brain. What insects don’t have is a cortex — nothing that even resembles one. To Hill, this means they can’t have consciousness. Without this dense, gray lid of neurons, consciousness is just not possible.

Other researchers aren’t so sure. They have begun to question whether consciousness originates from a place at all, spurring a rethinking of why it exists in the first place. However overgrown it might be in humans, the cerebral cortex didn’t emerge fully formed out of nowhere. It evolved over time, as did other neural structures. And if consciousness also evolved, then maybe the cortex isn’t the be-all, end-all of consciousness. Maybe consciousness is far more primitive. 

Insects might lack the hardware called a cerebral cortex, but they have plenty of other neural real estate. Could their brains perhaps contain the basis of consciousness? 

Like most good collaborations, it began over beer. Colin Klein, a philosopher, and Andy Barron, who studies the neural mechanisms of animals, then both working at Macquarie University in Sydney, met at a science pub night. They had a pint and struck up a conversation on what researchers call the neural correlates of consciousness. 

In the beginning, they agreed that insects were not conscious. But as they talked, they started to punch holes in their assumptions. They remembered that, in 2007, the Swedish neuroscientist Björn Merker argued that consciousness didn’t originate in the highly advanced cortex, but in a more primitive section of the brain at the top of the brain stem. Klein and Barron honed in on one part of that area, the tongue-shaped segment of neurons about an inch long called the midbrain, which controls a variety of involuntary functions, such as vision and motor control, as well as processing some sensory input. It was this latter task that attracted Merker’s attention for its potential role in consciousness. 

Klein and Barron found Merker’s argument compelling — and if it was true, insects might very well be conscious. In a 2016 paper in the Proceedings of the National Academy of Sciences, they argued that insects do have the functional equivalent of the human midbrain, which means they could very likely have some form of consciousness. 

“Consciousness is a sense of yourself in the world. It’s suffering. It’s bliss.”

Not many people believed the conclusion, Klein told me. A big mistake, he pointed out, is thinking that insect consciousness is like human consciousness. Humans tend to think of consciousness as the ability to worry ourselves into knots about future events that have an infinitesimal chance of happening — or to question whether other species have consciousness. But consciousness itself, Klein says, is much deeper and more primitive. It’s a sense of yourself in the world. It’s suffering. It’s bliss.

It’s hard to get more primitive than pain and pleasure. Even bacteria know kinds of pain and pleasure — they are hardwired to swim toward some signals but away from others. So do fish. And insects.

But so what? If insects have consciousness, what does that even mean?

A moral philosopher who has pondered this question is Peter Singer. Singer stopped eating meat in the late 1960s as a student at Oxford University, after a friend told him about the abuse of animals in the meat industry. Singer’s 1975 book “Animal Liberation” — widely considered to be the founding philosophy of the animal rights movement — laid bare the problems of overlooking suffering in everything from scientific research to food. 

But at first, insects weren’t on his radar. “I was always unsure about invertebrates, such as cephalopods and crustaceans,” he told me. “I wasn’t thinking very much about it. I was just hoping that they weren’t sentient and there wasn’t an issue there.”

Over the years, however, Singer has continued to ask himself about the nature of animal suffering and what enables it, biologically. He has come to the same conclusion as Klein and Chittka: that insects do have some sort of consciousness. 

But Singer takes it one step further: If insects are conscious, how should humans treat them? Take agricultural pesticides. Anything that causes mass suffering and death in its intended victims is problematic, he said, because whether or not those victims are conscious, they can feel pain. Thus, farmers should use whichever one causes insects to immediately lose consciousness — “the equivalent of a humane slaughter law.” 

I asked Singer if there was some sort of suffering math that could be calculated. If, say, a cricket is one-tenth as conscious as a chicken and can thus only suffer one-tenth as much, but it requires 100 crickets to get the same protein as a chicken, would we then be increasing the suffering in the universe by an order of magnitude? 

Singer paused for a minute, then nodded. “Maybe,” he said. It’s not that simple, he went on, but it’s something most governments should be thinking about, and they aren’t.

Most, but not all. Last November, the British government recognized crustaceans and cephalopods (octopi and squid) as sentient, and proposed legislation would make it illegal to boil lobsters alive. There are already laws barring the same cooking method in Switzerland and elsewhere.

In the end, I don’t know whether insects have consciousness or not. Nobody else can say for sure, either. I do, however, think the question is worth asking: What is it like to be a bee or an ant? We lose little by elbowing humans out of the center of every decision-making process, instead asking how our actions impact other animals, even small ones we think are dumb and gross. As Wilson put it: “We are living, suffering and enjoying beings in a whole world of other living, suffering and enjoying beings. And we should not be depriving them unnecessarily of their experiences.”