Pain is an experience that is as sensory as it is emotional and, therefore, presents a highly subjective burden This event is defined as an experience associated with a tissue injury but, curiously, sometimes the pain appears as a physical symptom of an emotional imbalance (somatoform disorder) without any specific physical trigger. Pain belongs to each person, since the physical and emotional state of the individual, in addition to their memories and previous experiences, plays an essential role in its perception.
When it comes to the rest of the animal kingdom, quantifying the intensity of sensations becomes even more complex. Ethology faces a series of dilemmas that are impossible to address on a day-to-day basis with complete accuracy, since feelings are difficult to record in measurable parameters and, furthermore, all results are subject to the interpretation of the researcher. Humans can make the mistake of humanizing other living beings without realizing it, since they do not have a voice to tell us what they are feeling at any given moment.
In an effort to discover the neurological and physiological processes of the animals around us, many ethological questions and investigations can be raised that can try to be elucidated with anatomical markers. Today we address one of the most interesting that can be stated: Do insects feel pain? Stay with us and find out.
All of us, to a greater or lesser extent, have been exposed to the world of invertebrates at some point in our lives. These very primitive beings seem practically “automatons”, since they do not seem to care about losing a limb, half their body or even their head Without going any further, every entomologist or curious person who has had the opportunity will have observed, with horror, how a grasshopper is devoured by a living praying mantis and, meanwhile, feeds carelessly on the stem of a leaf.
If insects felt pain as we conceive it, this observable reality would be impossible. Agony and despair would take over any living organism that perceives such pain and, therefore, it would not be able to perform any physiological function beyond attempting to escape. The key is contained in the definition of the term itself: other living beings do not have to perceive pain. In this point, It is essential to differentiate pain from nociception
Pain is a personal, subjective and non-transferable experience that includes the integration of negative emotions. On the other hand, in nociception, nociceptors (pain receptors) process potentially harmful stimuli against tissues and send signals to the nervous center of the living being to do something about it (if it has one). Most animals have the capacity for nociception, but this does not mean that they feel pain per se
If we get philosophical when following this train of thought, we can say that being able to perceive a harmful stimulus is not the same as feeling pain. When a harmful source is applied to the body of an insect, it flees from it, as it has superficial nociceptors that encode an escape response.
This makes all the evolutionary sense in the world: if the animal stays in that environment for too long, it dies and will not be able to reproduce. For living beings, the ultimate goal is to leave their genetic imprint in the form of offspring as many times as they can, so it is necessary to be able to perceive threats to survive as long as possible. If we do not assume the ability of species to respond to environmental damage, the mechanisms of natural selection are impossible to explain
Scientific evidence and the dilemmas of pain
Nociception is ubiquitous in the animal kingdom, but pain, not so much. This is a topic for another time, since it has been shown that rats, birds and other vertebrates can feel emotions beyond the basic ones, that is, those that respond to something more than a mere evolutionary mechanism.
To answer the question of whether insects feel pain, it would be necessary determine the neurological and subjective components that enable the experience of this sensory event Scientists should therefore ask themselves the following questions:
As you can imagine, Answering these questions 100% reliably, today, is completely impossible The reality is that we do not know what it takes to go from nociception to pain, since it is a question as ethereal as the nature of life itself. Now, science is not static, and as such, when faced with any question, we try to find possible answers.
In this case, we are going to focus our attention on the scientific article Nerve injury drives a heightened state of vigilance and neuropathic sensitization in Drosophilapublished in the journal Science Advances, in 2019. This publication tried to quantify the pain perceived by flies Drosophilaswith the action of γ-aminobutyric acid (GABA) and other components of the nervous system responsible for the transmission of painful impulses.
The researchers performed localized nerve damage on one of the flies’ limbs, and then the injury was allowed to heal completely. To the surprise of professionals, it was discovered that, Once the damage was received, the rest of the flies’ limbs became hypersensitive It is believed that these invertebrates are “prepared” to perceive pain on a smaller scale and, therefore, be able to respond more quickly to it on future occasions and maximize their chances of survival.
According to these discoveries, it seems that flies acquire a state of “hypervigilance” after the first injury. This, in a way, could be translated into They experience a different type of pain based on their experiences and, therefore, it acquires a subjective charge. Something as simple as this could demonstrate an obvious step from simple nociception to pain.
The evolutionary meaning of pain
We could go to sleep happy thinking that we have solved the dilemma, but in the world of science nothing is that simple. That something has been discovered can point to a direction, but never establish a dogma, unless the observed reality is repeated in all cases. Than the flies Drosophila Whether or not they feel pain is an open debate, but the reality is that We still do not have information on the vast majority of invertebrate taxa regarding this topic
In addition, professionals from the Entomological Society of Canada provide a final reflection that is at least interesting: what is the use of insects perceiving pain? Invertebrates have an extremely basic, but economical, nervous system. Having a nervous system like the human one entails a series of extreme physiological costs (our brain consumes 20% of the body’s glucose and oxygen), so is it really worth it?
For insects, it appears that the answer is no. They have nociceptors that allow them to escape a harmful stimulus as quickly and effectively as possible, so it is difficult to think of reasons why they would benefit from a more complex perception of a harmful event. They already maximize their chances of survival with what they have and, therefore, allocating more resources to a more complex emotion seems evolutionarily unfeasible.
Summary
Once again, we remind you that in this space we have not stopped moving in conjectures and ramblings, because no matter how much data is obtained, it is always subject to the interpretation of who collects it. We don’t even know what pain is in its entirety, so answering the question posed here with complete certainty is an impossible task.
What we can affirm (based on physiological evidence) is that, if insects feel pain, it is clear that they do not do it in the same way as we do. A more primary and basic nervous system, by definition, must entail a level of perception different from ours. From here, the reflections and ramblings are endless.
