Research that counters the hypothesis

Okay, I know I said I was going to post this on Monday, but that was a lie. Better late than never! (Note: this post is not late in the sense that points should be deducted; in fact, it is technically quite early.) In my last post, I described a study led by Dr. Lynne Sneddon from The Roslin Institute that appeared to give conclusive evidence of the presence of pain in fish. However, with every new piece of evidence, Dr. James L. Rose from the University of Wyoming seems determined to try and refute it. In his critique of the study by Sneddon et al., Rose lists several reasons why he thinks the study should not be considered particularly valid evidence for pain in fish.

For one thing, Rose accuses Sneddon et al. of assuming that "any behavior that is a reflex would be evidence of nociception but any behavior more complex than a reflex would be evidence of
pain." He invalidates this assumption by pointing to certain instances where humans themselves make certain complex, non-reflexive responses to harmful stimuli without being conscious (and therefore, not feeling pain)—for example, humans with "extensive damage" of the cerebral hemispheres.

Rose goes on to provide evidence (the lack of a neocortex) that fish do not have the capacity for pain, and perhaps not even the capacity for consciousness. "The burden of proof," he says, lies with Sneddon et al. to show that trout have the biological capacity to feel pain. The so-called "conclusive evidence" suggested by Sneddon, Rose claims, arose "only by citing previous studies that also used invalid criteria for pain, such as avoidance learning, which actually occurs unconsciously." He also accuses Sneddon of anthropomorphism.

Rose also provides reasons for why the behavioral results allegedly showing evidence of pain were "misinterpreted"—vast differences in the fish neurology compared to mammal neurology, as well alternative, apparently more plausible explanations for the "pained" fishes' behaviors.

This is not the only time Dr. Rose has criticized studies of fish pain. In fact, in one of his articles, Rose et al. commented on more than a dozen studies (including some by Sneddon, and another significant study by Nordgreen et al. that studied the reactions of fish to high heat), and "refuted" all of their reasonings that led to the conclusions that fish feel pain, through some of his logic stated above. Sneddon responded to Rose (rather acrimoniously, in fact) by criticizing him for his lack of a "track record" in animal neurology, for inserting his own "personal opinion[s]" into his work, and for implying that one can disprove but not prove the existence of pain in fish. Sneddon responds to Rose's anthropomorphism remark by accusing Rose himself of anthropomorphism by assuming that fish's bodies work the same ways humans' do. In his article "The Welfare of Fish," Professor George Iwama of Acadia University, while agreeing with many of Rose's points, conquers with Sneddon that "the basis for our respectful treatment" of fish should not rely "upon the outcome that fish...experience pain as we do."

Dr. Rose makes many good points. However, I would agree with Sneddon that he seems to be taking the "burden of proof" concept too far. Although I might agree with him that we cannot conclusively say that fish feel pain (like Sneddon seems to say), I don't agree that every pro-fish-pain conclusion by every study is automatically invalid. These studies aren't proof of fish pain, and maybe not even evidence beyond a reasonable doubt, but they can certainly still be considered evidence. Rose can go ahead and invalidate some of the conclusions certain researchers make, but he shouldn't discredit the research entirely. This is surely a topic worthy of further study.

Research that supports the hypothesis

All right, so this blog post is kind of a continuation of the previous one. I'll follow up on this one with another post on Monday, probably. Today's post will summarize and discuss some of the research that's been done in favor of the fish pain hypothesis, and Monday's will discuss some of the rebuttals to this research.

The rainbow trout, the species the 2003 Sneddon et al. study tested for fish pain.
(Image taken from ACNL Wikia)

I mentioned earlier that the name "Lynne Sneddon" kept coming up in my research. This is because her research team performed one of the most notable experiments in the history of the fish pain debate. In 2003, Sneddon et al. proved for the first time that fish have nociceptors—nerve cells that respond to tissue-damaging stimuli. However, since pain must include an "unpleasant...emotional experience" (as defined by the International Association for the Study of Pain), the presence of nociceptors alone does not prove that fish feel true pain. So Sneddon et al. continued testing, observing trout behavior after being subjected to harmful stimuli. The fish demonstrated "rocking" motions, similar to the motions certain mammals perform while in pain. Fish would also rub the negatively affected body areas onto solid surfaces, in motions that, according to Sneddon, "[did] not appear to be reflex responses." Put together, this research was said to be the "first conclusive evidence" of pain perception in fish.

All right, so here are some thoughts. As far as I can tell, even Sneddon's harshest critics don't seem to be contesting the fact that her discovery of fish nociceptors was genuine. However, as I mentioned earlier, simply recognizing negative stimuli and actually feeling pain are two different things. Sneddon claims that the observation of behavior in affected fishes is "conclusive" evidence that they are "pained," though I'm not sure I can say that so confidently. (Though of course, I am not the scientist.) Sneddon says that the behavior did not appear to be reflex responses, but does not provide anything with which to back up the claim. Furthermore, Sneddon's critic, Dr. James D. Rose, came up with seemingly valid reasons to doubt Sneddon's claim (reasons which I will elaborate on in my next blog post). This doesn't mean we should discredit this study entirely—the discovery of nociceptors is undoubtedly significant to the research question, and the behavior studied does provide evidence of pain in fish, if not absolute proof.

Opposing viewpoints

Dr. Lynne Sneddon seems to support fish welfare without question.
(Photo taken from Twitter)

Hey all. I finished the first draft of my Literature Review Assignment. Everything seems to be running smoothly. Pain in fish is definitely my research topic now—I won't be changing it again, I promise. The only concern I have at this point is that I have no idea how I'm going to be making a final argument when 1.) I'm not a scientist, and I'm basing my argument from science and 2.) there are as many scientific articles in support of the theory as there are against it.

One weird thing about that second point, though: many different articles that I've compiled are contributed on by the same people—Drs. Lynne Sneddon and James D. Rose are two very common names in this topic that argue for and against the fish pain theory, respectively. If you search "fish pain" in Google Scholar, you'll find that it's nearly impossible to find a scholarly article that doesn't at least reference the work of one of these two researchers.

I'm beginning to wonder if I might be getting a bit of a skewed view. Probably not too skewed, since all the scholarly articles are peer-reviewed. But it's still worth considering. For example, Lynne Sneddon's work is geared less toward the simple pursuit of knowledge and more toward animal welfare. That doesn't mean her data isn't reliable or that her logic isn't sound, but it could mean she might leave out possible deductions that could oppose her theory.

I'll give examples of some of the research I've found soon—hopefully before Monday night this time.