(ORDO NEWS) — The new work points to the ability of insects to truly experience pain and raises questions about the ethical treatment of these invertebrates.
Scientists from the UK conducted a large review of earlier research related to the behavioral and physiological aspects of the response of insects to painful stimuli.
The authors concluded that these invertebrates are able to experience pain in the same way as “higher” animals.
Such results raise questions again about whether insects are conscious and how ethical our usual ruthless treatment of them is.
An article by Lars Chittka and colleagues is being prepared for publication in Proceedings of the Royal Society B and is currently available on the preprint server.
Lars Chittka of Queen Mary University of London is known for his unusual experiments on the cognitive abilities of insects. This time, he and co-authors reviewed previous studies related to the experience of pain in these animals.
First of all, the authors emphasize the difference between nociception – the activity of the nervous system, which is caused by painful stimuli – and the “higher” subjective experience of pain. Nociception is undoubtedly present in insects and provides a quick response to dangerous stimuli.
But what about subjective experience? To define it, Chittka and colleagues look at the “descending order of nociception” (pain perception) – in other words, the ability of the nervous system to interfere with the automatic work of reflexes and produce a new response to a painful stimulus.
“One of the main properties of human perception is its ability to be modulated by brain signals,” one of the authors of the work said in an interview with The Newsweek.
“Soldiers can continue to fight, even when seriously injured, as long as the body’s own opiates suppress the nociceptive signal.
We can consciously bite the bullet and endure pain if such behavior allows us to gain additional benefits or recognition. So we wondered if there are similar mechanisms in the brain of insects.”
A review of the literature allowed scientists to find a whole series of examples of similar behavior in insects, allowing them to respond more flexibly and adapt to danger in various circumstances. In particular, when they feel pain, they demonstrate reduced appetite and inhibited eating behavior.
At the same time, unlike mammals, the neurons of these invertebrates do not have opioid receptors. Scientists suggest that other peptides, perhaps drosulfakinin, allostatin-C, or leukokinin, may play such a role in their nervous system.
All this leads to the conclusion that insects are capable of a true “subjective experience of pain”, like mammals.
Based on nociception and response to pain, Chittka and colleagues identify eight criteria on the basis of which it is possible to draw conclusions about the possible presence of consciousness: the presence of the nociceptors themselves; the presence of areas of the brain where information is integrated; the presence of connections between nocireceptor signaling pathways and integrative regions, and so on.
Based on these criteria, biologists draw the rather marginal conclusion that insects have everything they need for consciousness. They believe this raises new questions about the ethical handling of these invertebrates in agriculture and even scientific experimentation.
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