The Current State of the Science of Insect Sentience

The more we study sentience among nonhuman animals (animals) the more species are added to the sentience arena—the biodiversity of sentience is forever growing—and ethical questions about pain and suffering in many different animals, including insects, come to the fore.^1,2 For example, the emotional lives of insects are richer than many of us have ever imagined—not just in the ever-popular bees, but also in flies, mosquitoes, cockroaches, and termites too. (Darwin himself thought this! In 1872, he wrote that insects “express anger, terror, jealousy and love.”) A recent and detailed review of the evidence by Matilda Gibbons and her colleagues titled “Can insects feel pain? A review of the neural and behavioural evidence" makes it plausible that various insects are indeed sentient and feel pain.

Because science clearly shows that numerous animals other than ourselves are sentient beings, a shift in attitudes is in progress. Given what we know about animal sentience, it's time for more action—to use what we know on behalf of other animals.

Source: Egor Kamelev/Pexels.

Given the attention being directed to insect sentience, I'm thrilled that Dr. Bob Fischer, an expert on this topic, could answer a few questions about the state of the art of research in this area.

Marc Bekoff: How did you get interested in insect sentience?

Bob Fischer: I got interested in insects because I wanted to know how to eat. It’s easy to know what not to eat! Factory farms cause a lot of unnecessary harm; so, we have good reason to avoid the meat, eggs, and dairy products that come out of them. But that leaves lots of open questions about what you should eat instead. Just plants? What about bivalves? What about bugs? It all seemed very complicated at the time!

MB: How can we know whether insects are sentient?

BF: Great question! The short answer is that we can look at their behavior, we can look at their neurophysiology, and we can think about the evolution of sentience.

Let’s start with evolution. Remember: sentience didn’t just pop into existence! It evolved. And good theories about why it evolved can help us think about whether insects are likely to have it.

So, why did sentience evolve? Some hypotheses are: it lets animals represent what’s good and bad for them (via good and bad feelings), it motivates animals to get the good and avoid the bad, and it helps them set priorities (where stronger feelings signal more value or disvalue).

Those are pretty basic needs for organisms that need to move around in the world, balancing risks with opportunities. It’s plausible, then, that sentience evolved early in the history of life. And if so, then it would make sense for insects to have it!

On the behavior and neurophysiology side, insects have lots of the traits that scientists take to be indicators of sentience. They’ve got nociceptors, which means that they can detect negative stimuli. They have brains that can integrate information from different senses (including information from their nociceptors). We know that fruit flies appear to be less bothered by noxious substances when they receive pain-killers; that bumblebees make flexible tradeoffs between rewards and threats; that moth caterpillars tend their wounds; and that ants can learn to avoid things that might harm them.

None of this is a guarantee. But the more we learn about insects, the more impressive their abilities. When my team tried to compare the experiences of insects and other animals, we found differences but not huge ones. I think we underestimate insects because we can’t see them well; because they’re often framed as pests; and because it feels like they’re “cheap,” replaceable animals. But they aren’t! No animal is.

Last thing: Yes, there are lots of open questions here, but we shouldn’t make too much of our uncertainty. Usually, no one’s even tried to figure out what these animals can do. We need more research. This is one reason why I’m excited by groups like the Insect Welfare Research Society that are trying to draw attention to the needs of these neglected creatures. (To learn more about their work, join the listserv.)

MB: Who do you hope to reach with your work?

BF: Everyone! For now, though, I’m especially interested in reaching entomologists and other scientists who work with insects. The first step is to get the research community to take insects more seriously as individuals. As the people who know these animals shift their thinking, I hope that they’ll begin studying ways to reduce the conflicts between what’s good for humans and what’s good for insects. Yes, some insects carry diseases; some insects damage crops. However, the more we learn about how to deter and manage them humanely, the easier it will be for the rest of us to have better relationships with these animals.

MB: Why is this becoming such a "hot" field of research? Why are insect sentience and welfare attracting the attention of more and more researchers?

BF: I think it’s mostly a natural progression: people used to wonder whether birds were sentient; then, it was fish; after that, large invertebrates, like octopuses and lobsters; now, it’s insects. As I see it, researchers are just now “getting around” to some of the most abundant animals on the planet.

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As for the recent interest in insect welfare, that’s largely driven by the rise of insects as food. Because of worries about how we’re going to source protein as the human population grows and incomes increase, people are hunting for sustainable alternatives to the status quo. Some think that insects are going to be a big part of a greener food system and, as a result, there’s a lot of money flowing into intensive insect production. But as you might imagine, that raises lots of questions about how these animals are going to be reared and slaughtered. Since the scale is huge—we’re talking about trillions of individuals—researchers are realizing that it’s important to investigate how best to take care of these animals.

MB: Are you hopeful that as people learn more about insect sentience they will treat these amazing animals with more respect and compassion?

BF: I am. In fact, I’m one of the converts! I was pretty skeptical of insect sentience at one point; I didn’t think that insects mattered. But the more I’ve learned (here’s a great primer), the more I’ve come to care about them. And the more I care about them, the more hopeful I am that others will join me. Insects are fascinating and humbling creatures. I hope we can do more and better for them.