Do Insects Have Consciousness?

A new theory has scientists buzzing

Conscious Insect Illustration
Gert Albrecht

Amid the usual parade of creeping horrors—super lice, mayfly plagues and a “troll-haired insect discovered in remote Suriname”—the exterminator news site PestWeb recently shared a piece of unsettling intelligence.

“Insects Have Consciousness, Self-Awareness and Egos,” the headline read.

Whether or not the consciences of professional bug slayers were burdened by this revelation, other people were alarmed. We’re a far cry from “insect rights,” mused the bioethicist and animal rights advocate Peter Singer, but the prospect of bugs’ inner lives ups the ethical stakes.

This moral hornet’s nest was first stirred at a local meeting of the worldwide science and drinking club Nerd Nite in a Sydney, Australia, pub. Honeybee scientist Andrew Barron began chatting with philosopher Colin Klein, who initially swatted away the idea of insect consciousness. After all, insect brains are tiny and have just a million or so neurons, compared with a human’s average of 86 billion. Like many of us, Klein had assumed that insects are just collections of reflexes—that they are “dark inside,” he says—and this assumption jibed nicely with his habit of flushing the enormous cockroaches at his apartment down the toilet.

But then the two Macquarie University professors began to explore the research. One prominent theory holds that the core of human consciousness is not our impressive neocortex, but our much more primitive midbrain. This simple structure synthesizes sensory data into a unified, egocentric point of view that lets us navigate our world.

Insects, Barron and Klein now argue, have midbrain-like structures, including a “central complex,” that seem to allow bugs to similarly model themselves as they move through space. They cite evidence ranging from a study that used microelectrodes to look at fly brain activity, to seemingly macabre research showing that when a jewel wasp injects venom into a cockroach’s central complex, the zombiefied prey will allow itself to be led by the antennae into its predator’s lair.

While the human midbrain and the insect brain may even be evolutionarily related, an insect’s inner life is obviously more basic than our own. Accordingly, bugs feel something like hunger and pain, and “perhaps very simple analogs of anger,” but no grief or jealousy. “They plan, but don’t imagine,” Klein says. Even so, insects’ highly distilled sense of self is a potential gift to the far-out study of consciousness. Probing the insect brain could help quantify questions of what it means to think that vexed the likes of Aristotle and Descartes, and could even aid the development of sentient robots.

On the other hand, it complicates daily life. “I still flush,” Klein says of his cockroaches. “But I hesitate.”

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