We have always seen insects as innate, mindless creatures with robotic-like reactions to the world and all its impulses.
But the closer we look, we find surprisingly complex behaviors, from bees communication through dance to the incredible feats of cooperating with ants, and now we have mounting evidence that these tiny creatures who run our world may also be experiencing pain.
Sensation of pain–the sensory nervous system’s detection of unpleasant stimulation including chemical burn, sharp cut and bruising pressure–elicits a variety of physiological and behavioral responses in animals. One of those things could be the perception of pain.
It is well documented that insects have responses to avoid potentially harmful contact.
Moreover, experiments in 2019 revealed that the commonly studied fruit fly, fruit flyShe developed symptoms of chronic pain after researchers removed a fruit fly’s leg. Once the fruit fly had completely healed, the researchers found that the corresponding leg of the fruit fly became hypersensitive.
The authors traced this to the fact that the fly lost the “pain-suppression” mechanism in its nerve tendon. The pain-brake mechanism moderates the sensation of pain, but in fruit flies, when the sensory nerves are excessively stimulated, it eliminates the brakes completely.
But, since bacteria will shy away from unpleasant stimuli, detecting pain in the afterlife is not as simple as observing a negative reaction to harmful contact. To consciously register feeling pain, we need a complex physiological system that connects our brains, and perhaps even our emotions.
In mammals, pain receptors (pain receptors) send an alert for bad stimuli to our brains, where neurons generate the feeling of negative, subjective, physical and emotional pain.
Studies show that the feeling of pain and pain can be regulated independently of each other, and distinct systems have been identified to regulate each.
These systems have not been fully identified in insects.
“One of the hallmarks of human pain perception is that it can be modulated by neural signals from the brain,” Matilda Gibbons, a neurobiologist at Queen Mary University, told Newsweek.
“Soldiers sometimes ignore serious battlefield injuries because the body’s opioids suppress the pain-causing signal. Thus, we asked whether the insect’s brain contains the neural mechanisms that make it reasonable to experience pain-like perception, rather than simply feeling basic pain.”
Gibbons and colleagues reviewed the scientific literature and found several lines of evidence indicating that this mechanism is present in insects.
While they lack the opioid receptor genes that regulate pain in us, they produce other proteins during traumatic events that can serve the same purpose.
Behavioral evidence also indicates that insects have responses that suppress responses to molecular pathways that destroy connectivity, both for the peripheral and central nervous system. For example, the presence of a sugar solution prevents natural bees from avoiding unpleasant stimuli.
Anatomically speaking, insects have neurons descending from the brain to the part of the nerve cord where their defensive reaction against harmful touch originates.
Furthermore, the tobacco worm uses mitigating behaviors after infection, such as grooming.
Each of these things may not be definitive in isolation, but taken together, they suggest that insects have some kind of pain-response control system, similar to ours.
“We argue that insects likely possess central nervous control over pain, based on behavioral, molecular, and anatomical neuroscience evidence,” the team concludes in a statement. “Such control corresponds to having the experience of pain.”
Since insects are such a large and diverse group, it is quite possible that the complexity of regulating their awakening and possible feelings of pain differ significantly among themselves.
However, the possibility of their pain raises important ethical questions for further investigation – particularly in light of the proposed collective farming of these animals in the future.
“We stand at an important crossroads of how to feed a population expected to reach 10 billion by 2050,” the researchers say.
“While traditional livestock farming is a major contributor to climate change, the United Nations recommends mass production of insects for food. However, the ethical implications have not been comprehensively considered, as protecting animal welfare tends not to cover insects.”
This research was published in Proceedings of the Royal Society B: Biological Sciences.
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