Sadly, to know life is to know pain. This is an aspect of our biology that is fully integrated into the very fabric of the human condition, although as we will see soon, we are certainly not the only living things that experience pain. We are not the only living beings who suffer because of it, not at all.
We could say that one of the main characters in human history is pain itself; a character that most of us constantly avoid meeting, rather unsuccessfully. The unquestionable fact is that pain is a fact of life. It is understandable that we attempt to avoid pain at virtually all costs, as it clearly is not a desirable sensation for most of us. However, it is hard to disagree with the fact that pain is essential for survival. You see, pain is probably the very first sign that tells you that something is wrong with your body. Seen from this perspective, pain is an important mechanism for self-preservation, there is little doubt about that. Therefore, counterintuitively, pain increases your prospects of living longer and healthier as well, since it will help avoid dangerous situations or correct them if you cannot avoid them.
A case in point is a rare disease (1) known as congenital insensitivity to pain, or congenital indifference to pain, sometimes also referred to as congenital analgesia. This is a disease that belongs to a group of conditions whose underlying feature is nerve damage of the peripheral nervous system (which essentially includes all nerves in the body except the brain and spinal cord). Surprisingly, the first formal description of such a condition was reported relatively recently, in 1932 (2). Many patients suffering from this disease are able to feel pressure and can distinguish between pointy and dull objects, but are unable of feeling actual pain. These patients are also unable to perceive other painful stimuli such as burns, and infection-derived painful sensations. Essentially, pain is not part of these patients daily lives and over time this fact frequently leads to a sad history of injuries/diseases that usually cut their lives short. For example, let’s say that a person affected with this disease gets appendicitis. One of the main symptoms of appendicitis is abdominal pain. Therefore, if someone with this condition is unable to feel pain, the prospects of injury or worse dramatically increase. The patient must be alert to other signs of trouble pointing at that urgent painful signal in order to get medical attention in time.
It is well-known that in ancient times people believed that pain was divinely ordained. In many cases pain was seen as punishment or penitence, but in some other cases, pain was inflicted to a person without an apparent reason; in essence, pain seemed to be just a whim of the gods. While there is no doubt that to a sufferer pain feels like punishment, we now know that pain has a biological cause. This acknowledgment was the basis for the assertion by the philosopher Michel Foucault (1926-1984) that modern medicine essentially began by recognizing that pain could be rather useful to physicians as an objective measurement of illness. In brief, the argument states that modern medical practice effectively began when the physician stopped asking, “What’s wrong?” and began asking, “Where does it hurt?” (3)
All this talk about painful sensations inevitably brings us to our nervous system, which is a truly awe-inspiring work of nature. Its function is to receive information, analyze it and act upon it, consciously or unconsciously. Of course, tissue damage is part of the information that our nervous system works with, usually interpreted by our brain as pain.
As with any sensation, pain perception is a consequence of the physiology of our nervous system. We will not get into the details of how the brain is able to do this, but there are quite a few useful and quite accessible works that you may want to look at should you wish to know more about the nervous system and its many wonders (4). In the meantime, let’s explore a few details that are oftentimes not explicitly mentioned when talking about pain.
A semi-philosophical school of thought proposes that to feel true pain, an organism must display a nervous system architecture complex enough to generate the phenomenon of consciousness, never mind that we are not sure what consciousness is or how the brain generates it. In fact, a formal definition of consciousness that is universally accepted by neuroscientists remains elusive, end of story. However, as far as pain conscious perception is concerned, there are some scholars who argue that the perception of pain —in various forms, from physical to emotional pain— is exclusive to primates, including ourselves. In a nutshell, they claim that our perceptions and emotions are unique in the animal kingdom, and especially organisms like us. I highly doubt this proposition, for reasons both scientific and pragmatic.
Let’s consider the following:
To begin with, as I said above, we do not quite understand exactly how consciousness comes from nervous system activity, not in humans, not in other organisms, period. Anyone who claims to have a complete understanding of consciousness is at best, mistaken and at worst, well, less than truthful. This is not to say that progress is not being made in this area, as there are many scientists with various degrees of competency who are furiously studying this issue, but at this point in time, we humans have just the bare rudiments of a true theory of consciousness.
In more practical terms, it is very hard to argue that animals feel pain —or at the very least something very much like it—and can also express something very much like emotions. For example, as many pet owners through the millennia have experienced, try stepping on the tail of the proverbial cat and see what happens. Also, think about the demeanor of most dogs toward their humans —I am of course, a dog person (:-)…—. Dogs are capable of behaviors that can only be properly described as “loyal”, even “loving” at times. And by the way, do not even try to tell me that dogs do not display behaviors very much like “regret” or “embarrassment” when they misbehave! I’ve seen it, and probably you have seen it too.
Partly as a consequence of these types of observations, it is becoming more accepted that “lower” animals do feel pain or, again, at the very least something very much like it based on their behavioral responses. In fact, we don’t even have to limit ourselves to vertebrates. For example, I have seen it in my own line of research work using planarians, and I am not alone. It is evident to all of us flatworm researchers that sometimes these worms clearly do not like to be exposed to certain chemicals, and display what could be interpreted for all intent and purposes as “distress” (5). Also, there are many other examples of these invertebrate behaviors; think about octopi and insects for instance (6).
I find myself in complete agreement with Charles Darwin when he said: “The difference in mind between man* and the higher animals, great as it is, certainly is one of degree and not of kind.”
In a very real sense, it is very unlikely that we will ever be able to know exactly how another human feels, thinks or perceives pain, let alone a non-human organism. Several distinguished thinkers have all but ruled out this possibility purely on philosophical grounds. I tend to agree with their line of thought, at least in principle (7). However, the concept of “never” has rarely made a true scientist stop trying. I wouldn’t discard this possibility just yet, only the future will tell if we are able to solve the consciousness puzzle.
However, even if we never achieve a complete understanding of consciousness, in my mind there is very little doubt that other organisms feel pain (see the example of the proverbial cat above, and the other examples). This means that there is a concrete, undeniable case for us humans to show compassion for our fellow creatures. This has implications not only for the companion animals that we share our lives with, but also for the multiplicity of animals that we raise for food. In fact, some even may use this rationale to do away with this practice altogether. I believe that this is at least in part the thesis of a very interesting book that I am beginning to read and hope to review for you soon…-ish.
*And of course, I include women here as well. By the way, hat tip to Sari J. Nichols, master editor!
(1) Depending on the source, it seems that there are anywhere from twenty up to two hundred cases reported in the medical literature (ghr.nlm.nih.gov/condition/congenital-insensitivity-to-pain and drmarkgriffiths.wordpress.com/tag/congenital-analgesia/). At any rate, it is clear that is a rare disease indeed.
(2) Please see: Dearborn (1932) A case of congenital pure analgesia. Journal Nerv Ment Dis 75: 612-15.
(3) Please see: Knowlton and collaborators (translators) (2004) Foucault M: The Crisis of Medicine or the Crisis of Antimedicine? Foucault Studies 1:5-19.
(4) For example please see: cell.uchc.edu/pdf/fein/nociceptors_fein_2012.pdf. Also, you may want to see Gibb (2012) The Rough Guide to the Brain, and O’Shea (2006) The Brain: A Very Short Introduction. If you want a little bit more details on the brain, there is an absolutely delightful book: Beyond the Zonules of Zinn: A Fantastic Journey Through Your Brain, by David Bainbridge.
(5) To go over a particularly relevant example of this behavior, please see: Jenkins (1967) Aspects of planarian biology and behavior, pp. 116–43, in: Corning and Ratner, Editors (1967) The Chemistry of Learning: Invertebrate Research. This is an invaluable book including many examples of planarian research, in particular about their behavior.
(6) For a couple of recent paper on the topic please see: Fiorito and collaborators (2014) Cephalopods in neuroscience: regulations, research and the 3Rs. Invert Neurosci. 14(1):13-36, and Gerber and collaborators (2014) Pain-relief learning in flies, rats, and man: basic research and applied perspectives. Learn Mem. 21(4):232-52.
(7) For example, see the insightful essay by Thomas Nagel: What is it like to be a bat? Found at: organizations.utep.edu/portals/1475/nagel_bat.pdf
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