This summer entomologist Lars Chittka made another plea in Scientific American for the recognition of insects as capable of emotion. It’s been shown that bumblebees can learn “specific strategies for opening a puzzle box” by mimicking the behavior of previously trained bees. But, he says, it goes beyond that:

Bees, for example, can count, grasp concepts of sameness and difference, learn complex tasks by observing others, and know their own individual body dimensions, a capacity associated with consciousness in humans. They also appear to experience both pleasure and pain. In other words, it now looks like at least some species of insects-and maybe all of them-are sentient. 

LARS CHITTKA, “DO INSECTS FEEL JOY AND PAIN?”, SCIENTIFIC AMERICAN, JULY 1, 2023

He decided to test also for “joy” and “pain”:

Some years ago we trained bumblebees to roll tiny balls to a goal area to obtain a nectar reward — a form of object manipulation equivalent to human usage of a coin in a vending machine. In the course of these experiments, we noticed that some bees rolled the balls around even when no sugar reward was being offered. We suspected that this might be a form of play behavior. 

CHITTKA, “JOY AND PAIN“

And pain?

We gave bees a choice between two types of artificial flowers. Some were heated to 55 degrees Celsius (lower than your cup of coffee but still hot), and others were not. We varied the rewards given for visiting the flowers. Bees clearly avoided the heat when rewards for both flower types were equal. On its own, such a reaction could be interpreted as resulting from a simple reflex, without an “ouch-like” experience. But a hallmark of pain in humans is that it is not just an automatic, reflexlike response. Instead one may opt to grit one’s teeth and bear the discomfort — for example, if a reward is at stake. It turns out that bees have just this kind of flexibility. When the rewards at the heated flowers were high, the bees chose to land on them. Apparently it was worth their while to endure the discomfort. 

CHITTKA, “JOY AND PAIN“

Chittka worries about the ethics of pain inflicted on insects use in research and on insects raised for human and animal food. Recalling an early career experience, he tell us, “Pain is a conscious experience, and many scholars then thought that consciousness is unique to humans.”

Do Insects Have Sentience, or Emotion?

What Chittka and others are gradually learning is that insects may have sentience, as mammals do — the ability to feel things as a self, rather than simply record and react to them, like a machine.

Decades ago, philosopher Thomas Nagel asked the iconic question, “What is it like to be a bat?” The point of his question was this: If there is something that it “is like” to be a bat, then bats are sentient. By way of comparison, there may be nothing that it “is like” to be a sea cucumber. The sea cucumber’s attraction, avoidance, and learning reactions may be controlled entirely in the way that a machine’s reactions are, with no basis or need for sentient experience. We don’t know that for sure but, in the absence of any apparent evidence of intelligence, it is a reasonable guess.

Assessing bee consciousness is complex because bees appear to have a sort of hive mind; the colony acts as a whole without the individual bees needing to understand the big picture. Thus the whole can be smarter than the sum of its parts.

Bees diligently fanning at the hive entrance to cool down the hive:

Is There a Tree of Sentience?

In recent years, we’ve been looking at the remarkable intelligence feats of the octopus. The octopus is not more intelligent than, say, the crow, the elephant, or the chimpanzee. But the fact that it can even be compared with them gives pause for thought: Most life forms known for intelligence are endothermic (warm-blooded), long-lived social vertebrates — that is, mammals and birds. The octopus is an exothermic (cold-blooded) short-lived solitary invertebrate with nine interacting brains, whose relatives include nautiluses and clams (!). If there is anything like a tree of intelligence, the octopus is certainly not where it should be in evolutionary terms. And if there isn’t such a tree, perhaps evolution is not what we are encouraged to think. Or at any rate, it does not operate on the principles that we are encouraged to think it does.

It may be that researchers will find something roughly similar when they study sentience. That is, rather than all insects being sentient, like mammals, only some will prove to be. Well then, if sentience, like intelligence, can be independent of phylogeny (place in Darwin’s tree of life), much that we have taken for granted about the history of life might need rethinking. We shall see.

Efforts to relate insect consciousness to human consciousness are doomed from the start because the distinguishing features of human consciousness are abstract thinking and moral choice. That, and no other fact accounts for why Lars Chittka is worried about the ethics of causing pain to farmed or lab insects. One thing we can be sure of: Fellow insects, irrespective of where they place in the animal intelligence stakes, are not thinking about any such thing.

Cross-posted at Mind Matters.