There’s Growing Evidence That Insects Feel Pain, Just Like Us
We have long seen insects as instinctive, mindless creatures with robotic-like reactions to the world and all its impulses.
But the closer we look, the more surprisingly complex behaviors we discover, from bees communicating through dance to the incredible cooperative feats of ants, and now we have more and more evidence that these little creatures that rule our world can also feel. pain.
Nociception—the sensory nervous system’s detection of unpleasant stimulation, including chemical burning, sharp cutting, and bruising pressure—triggers a variety of physiological and behavioral responses in animals. One of them can be the perception of pain.
It is well documented that insects have avoidance responses to potentially damaging contact.
Additionally, in 2019, experiments revealed that the commonly studied fruit fly, Drosophila, showed symptoms of chronic pain after researchers removed the fruit fly’s leg. After the fruit fly completely healed, the researchers found that the fruit fly’s contralateral leg became hypersensitive.
The authors attributed this to the fact that the fly lost its “pain brake” mechanism in its nerve cord. A pain brake mechanism quiets pain perception, but in fruit flies, when sensory nerves were overstimulated, it completely killed the brake.
But, as even bacteria shy away from unpleasant stimuli, detecting pain in another life isn’t as simple as monitoring a negative reaction to a harmful touch. To consciously register a sensation of pain, we need a complex physiological system that connects to our brain, and perhaps even our emotions.
In mammals, nociceptors (pain receptors) send an alarm for bad stimuli to our brain, where neurons generate the negative and subjective, physical and emotional sensation of pain.
Studies show that nociception and pain can be regulated independently of each other and have identified distinct systems for the regulation of each.
These systems have not yet been fully identified in insects.
“One of the hallmarks of human pain perception is that it can be modulated by nerve signals from the brain,” Matilda Gibbons, a neurobiologist at Queen Mary University, told Newsweek.
“Soldiers are sometimes unaware of serious battlefield injuries since the body’s opiates suppress the nociceptive signal. We therefore asked whether the insect brain contained the nerve mechanisms that would make it plausible to experience painful perception. , rather than just basic nociception.”
Gibbons and his colleagues reviewed the scientific literature and found several lines of evidence suggesting that this mechanism is present in insects.
Although they lack the opioid receptor genes that down-regulate pain in us, they do produce other proteins during traumatic events that could serve the same purpose.
Behavioral evidence also suggests that insects have molecular pathways that suppress damaging touch responses for both their peripheral and central nervous systems. For example, the presence of a sugar solution suppresses the bumblebee’s normal avoidance of unpleasant stimuli.
Anatomically, insects have neurons descending from the brain to the part of their nerve cord where their defensive reaction against damaging touch originates.
Additionally, the tobacco hornworm even uses mitigation behaviors after being injured, such as grooming.
Each of these things may not be definitive in isolation, but taken together they seem to indicate that insects have some kind of pain response control system, similar to ours.
“We argue that insects most likely have central nervous control over nociception, based on behavioral, molecular, and anatomical neuroscientific evidence,” the team concludes in a statement. “Such control is consistent with the existence of an experience of pain.”
However, since insects are a large and varied group, it is quite possible that the complexity of their regulation of nociception and potential pain sensations also vary considerably between them.
The prospect of their pain, however, raises important ethical questions for further investigation – especially in light of the proposed mass breeding of these animals in the future.
“We are at an important crossroads in how to feed a human population that is expected to reach 10 billion by 2050,” the researchers say.
“While conventional farming is a major contributor to climate change, the United Nations recommends the mass production of insects for food. However, the ethical implications have not been carefully considered, as the protections of the well -being animal tend not to cover insects.”
This research was published in Proceedings of the Royal Society B: Biological Sciences.