What insects can tell us about the origins of consciousness

TLDR

The evolution of consciousness is a hotly debated topic that requires examining its distribution across the animal phylogenetic tree, noting that vertebrates rely on integrated midbrain structures for subjective experience while insects possess analogous but distinct neural systems that evolved as efficient solutions to sensory reafference and navigation. The authors propose that insects possess a basic capacity for subjective experience. Insects have brain structures that perform functions analogous to vertebrate midbrain integration, enabling subjective experience. The authors conclude that insect brains support subjective experience and that this capacity originated in the Cambrian.

Abstract

How, why, and when consciousness evolved remain hotly debated topics. Addressing these issues requires considering the distribution of consciousness across the animal phylogenetic tree. Here we propose that at least one invertebrate clade, the insects, has a capacity for the most basic aspect of consciousness: subjective experience. In vertebrates the capacity for subjective experience is supported by integrated structures in the midbrain that create a neural simulation of the state of the mobile animal in space. This integrated and egocentric representation of the world from the animal’s perspective is sufficient for subjective experience. Structures in the insect brain perform analogous functions. Therefore, we argue the insect brain also supports a capacity for subjective experience. In both vertebrates and insects this form of behavioral control system evolved as an efficient solution to basic problems of sensory reafference and true navigation. The brain structures that support subjective experience in vertebrates and insects are very different from each other, but in both cases they are basal to each clade. Hence we propose the origins of subjective experience can be traced to the Cambrian.