Pushing the Boundaries

Abstract

Abstract The idea of pain in insects has often been dismissed on the grounds that insects will continue normal feeding and mating behaviours despite catastrophic injury. But this is compatible with insects having aversive experiences in response to other stimuli, such as heat, and there is emerging evidence that they do. Importantly, though, sentience is not just pain, and there are ways to make a case for insect sentience that do not proceed via responses to noxious stimuli. There is evidence that insects have a behavioural control unit functionally similar to the vertebrate midbrain. There is also evidence, mainly from bees, of working memory and of forms of associative learning that seem to be facilitated by conscious experience in humans. These lines of evidence push us to take seriously the possibility of sentience in insects. When we turn our attention to molluscs other than the cephalopods and other arthropods we find a frustrating paucity of studies looking for markers of sentience. These animals should be seen as investigation priorities.