Insect emotion and consciousness
There is growing interest in the possibility that insects and other invertebrates could have emotion-like states that might even be consciously experienced. Now a study by Clint Perry, Luigi Baciadonna and Lars Chittka in Science provides evidence that bumblebees may have positive emotion-like states, adding to a previous study by Melissa Bateson and colleagues on negative states in honeybees. Perry et al. showed that an unexpected sucrose reward, that could be likened to a nice surprise inducing a positive state as it would in humans, led to 'optimistic' judgements of an ambiguous situation, an indicator of positive emotional states in people. They also showed that this state decreased sensitivity to a negative event - simulated predation - and that both effects appeared to be mediated by the actions of dopaminergic systems known to be involved in reward processing in both humans and insects. Whether this 'emotion-like' state is accompanied by a conscious feeling is, however, unanswered by the study as the authors and a commentary by Mike Mendl and Liz Paul make clear. This is a critical question from an animal welfare perspective. If we believe that concerns about animal welfare are, for most people, motivated by an assumption that other species can consciously feel emotional states such as fear or anxiety and hence suffer, then finding emotion-like states in invertebrates would widen the scope of concern, but only if these states can be felt by the animals. The question of consciousness in other species is contentious, but a recent paper by Andrew Barron and Colin Klein in Proceedings of the National Academy of Sciences argued that insect brains may indeed be capable of 'phenomenal consciousness' - the capacity to be aware of sensations and emotions. This has generated correspondence and counter-argument in that journal, and also a series of commentaries on a similar article by the same authors in the new journal Ani mal Sentience. Whilst we do not have unequivocal answers at present, it seems that scientists are beginning to take the possibility of invertebrate emotion and consciousness seriously, and more studies can be expected in this exciting new research area.
(Photo: M. Mendl)