08/01/2024
The controversy behind animal sentience
As will become apparent from the following discussion the debate over animal sentience has, like a growing number of present-day issues, become rather polarized.
A case in point was the recent annual meeting of the Canadian Veterinary Medical Association (CVMA). A summit was held on “Animal Sentience: What Does It Mean, Why Is It Difficult to Define, and What Effect May It Have on the Veterinary Profession?” Doctor Tim Arthur, the CVMA’s newly-elected president, told me this was the first time this topic was discussed at one of their conventions. He directed me to the recently issued CVMA position statement on animal sentience, which states: “Sentience in this document means having the capacity to experience positive and negative feelings such as pleasure, excitement, fear, hunger, pain, and distress … The CVMA holds that many species of animals are sentient.”.
Professor Georgia Mason, in the department of Integrative Biology at the University of Guelph, was one of the speakers at the conference. I contacted her to seek her views on animal sentience. She said she fully supported the CVMA’s position paper. In response to my question, she explained the difference between sentience and consciousness by saying that sentience is a type of basic consciousness. “It is the ability to feel or be aware, sometimes described as the ‘what it is like’ aspect of a state. At the heart of sentience is an animal’s capacity for pain or the other forms of conscious affect.
“Sentience does not imply self-awareness, theory of mind, or anything else ‘higher order’ (i.e. complicated/cognitively sophisticated).” Prof. Mason uses sentience to refer to just the subtype that is most ethically relevant, emotions, an animal’s capacity for pain or other forms of conscious affect. Prof. Mason has referred to measures such as discriminating between stimuli, displaying Pavlovian conditioning, and even learning simple instrumental responses as “red herrings” that should not be used to infer sentience because they are also present in non-sentient organisms, notably those lacking nervous systems, like plants and protozoa. In Canada, the Canadian Council for Animal Care, “utilizes affective states as the primary determinant of animal welfare”. while internationally, the World Organization for Animal Health says that “an animal experiences good welfare if the animal is … not suffering from unpleasant states such as pain, fear and distress”.
Prof. Mason, who describes herself as a passionate animal welfare advocate, agrees with the above. “Pain and suffering is morally relevant. We need to think, ‘Can we reduce it?’ The guiding question should perhaps not be ‘is there evidence that this species is sentient?’ but rather ‘are we sure it is not?’”
The Cambridge Declaration on Consciousness, signed by a prominent group of scientists, which Prof. Mason thinks goes too far, states that “the absence of a neocortex does not appear to preclude an organism from experiencing affective states. Convergent evidence indicates that non-human animals have the neuroanatomical, neurochemical, and neurophysiological substrates of conscious states along with the capacity to exhibit intentional behaviors.
Personally, I agree with this statement. It seems to me that many scientists overvalue the role neurons and the neocortex play in consciousness. There is little difference between neurons and other cell types. Synaptic proteins, ion channels, and gap junctions already existed in our unicellular ancestors and were used by electrically active cells to co-ordinate their actions at the beginning of time. Neurons evolved from these much simpler cell types and some of the brain’s speed-optimized functions emerged around the time of bacterial biofilms. Neurons are specialized cells like red blood cells or liver cells But there is nothing magic about neurons.
This conversation about animal sentience reminds me of the long-held view in medicine that very young children feel no pain. As a result, the majority of newborns were operated on without anesthetics or any type of sedation causing untold suffering, increased morbidity and mortality.
In 1987 a survey of neonatal nurses demonstrated that 79 per cent thought analgesia was underused, with 33 per cent of babies receiving no post-operative analgesia and 34 per cent receiving no analgesia before invasive procedures. A year later, another survey found that 15 per cent of pediatric anesthetists thought babies less than I month old could not feel pain, none prescribed preoperative op**tes, 98 per cent did not prescribe op**tes for minor procedures, 30 per cent did not prescribe op**tes for major procedures, and 48 per cent did not prescribe post-operative op**te analgesia.
In the magazine Birth two letters by mothers appeared on this subject in 1986. One of them read like this.
“Ten years ago, our prematurely born son, Edward, was shunted for hydrocephalus while paralyzed with curare,” one mother wrote. “Although he could not move, cry, or react in any way, he could see, hear, and feel as large incisions were cut in his scalp, neck, and abdomen; as a hole was drilled in his skull; as a tube was inserted into the center of his brain, then pushed down under the skin of his neck, chest, and abdomen and implanted deep in his abdominal cavity.
“It is a source of great anguish to me that my husband and I signed a form allowing such an operation to take place, but we were told Edward might die or become brain damaged without the operation and that the anesthesia might kill him. Besides, the doctors assured us, these babies don’t really feel pain. I suspected then, and know now, that this is just not true.”
“To this day, our severely re****ed son will allow no one to touch his head, neck, or abdomen. Even heavily tranquilized, he reacts to the simplest medical procedures or the mere sight of the hospital with violent trembling, profuse sweating, screaming, struggling, and vomiting. I can’t help feeling that on some level he still remembers the hideous pain.”
It wasn’t until 1987 that the medical profession finally woke up from its self-serving state of ignorance, by the publication of a groundbreaking paper by K.J.S. Anand, head of the department of anesthesia at Harvard Medical School, in the prestigious New England Journal of Medicine. His conclusion: “Numerous lines of evidence suggest that even in the human fetus, pain pathways as well as cortical and subcortical centers necessary for pain perception are well developed late in gestation, and the neurochemical systems now known to be associated with pain transmission and modulation are intact and functional.”
I wonder whether a similar fate awaits the narrow definition of animal sentience.
I thought that perhaps Dr. Nicolas Rouleau may be able to shed some light on the topic. So, on a sunny day in July, I drove to Wilfrid Laurier University to meet with Nic, as he likes to be called. Sitting in his fifth-floor office in the Department of Health Sciences I asked him what he thought of Prof. Mason and J.M. Lavery’s paper on animal sentience. “The authors,” he remarked, “remove supposed ‘red herring’ measures of sentience precisely because they are present in a group of organisms that they’ve a priori determined are non-sentient. Theirs is a circular argument which is not based on evidence but simply a prejudice, namely the lack of a nervous system.”
Nic is a neuroscientist who contends that all attributions of cognition (i.e., mental actions), including sentience, are always inferred based on embodied behaviours, including verbal self-report in humans. He says, “If felt states in humans and other animals are always inferred, why is the same leap from observable behaviour to inferred sentience not afforded to other organisms, including plants?”
I want to know how he differentiates between simple reflexes and conscious behaviour. “Behaviours are fundamentally cognitive because they are goal-directed, anticipatory, flexible, and adaptive. These qualities are unlike simple reflexes, which are comparatively rigid, typically inborn, and do not require any accompanying mental action.”
I wonder, does a being require a neural substrate to be sentient? “Not at all. A function is said to be substrate-independent when it can be achieved without the contingency of a particular material or physical medium. Computation, for example, can be implemented in many ways by machines and living organisms alike. It is quite possible that felt states can be achieved in multiple ways and by many different biological substrates.”
After a most stimulating morning Nic took me on a tour of his lab where he introduced me to his wife, Nirosha Murugan, who is also a professor at WLU. These two young scientists are doing incredible research on cancer and embodied and bioengineered tissues to model neural diseases. I would not be surprised if they receive the Nobel eventually.
Nic did postgrad work at Tufts university in Boston. One of his mentors was Michael Levin, Distinguished Professor of Biology and Director of the Allen Discovery Center. Prof. Levin conducts research at the intersection of developmental biology, computer science, and behavioural science. In my opinion, he is one of the most brilliant scientists alive today. A few years ago, at the end of a long conversation with him, I asked what does being human mean to him. His answer still rings in my ears, “being human is to have moral concern and compassion for every being.”
I suggest we should keep this in mind when we consider the sentience and welfare of animals, including humans.
