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Full-Text Articles in Evolution

Cognitive Evidence Of Fish Sentience, Jonathan Balcombe Jan 2016

Cognitive Evidence Of Fish Sentience, Jonathan Balcombe

Animal Sentience

I present a little-known example of flexible, opportunistic behavior by a species of fish to undermine Key’s (2016) thesis that fish are unconscious and unable to feel. Lack of a cortex is flimsy grounds for denying pain to fish, for on that criterion we must also then deny it to all non-mammals, including birds, which goes against scientific consensus. Notwithstanding science’s fundamental inability to prove anything, the precautionary principal dictates that we should give the benefit of the doubt to fish, and the state of the oceans dictates that we act on it now.


Why Human Pain Can’T Tell Us Whether Fish Feel Pain, Victoria A. Braithwaite, Paula Droege Jan 2016

Why Human Pain Can’T Tell Us Whether Fish Feel Pain, Victoria A. Braithwaite, Paula Droege

Animal Sentience

In his target article, Key (2016) reviews the neuroanatomy of human pain and uses what is known about human pain to argue that fish cannot experience pain. We provide three reasons why the conclusions reached by Key are unsupported. They consider (i) why it is not sufficient to conclude that only human neural structures can process conscious pain, (ii) why an understanding of pain in humans and non-human animals needs to be based within a framework of consciousness, and (iii) evidence already exists that fish treated with noxious stimuli lose the ability to perform normal behaviours: This was a behavioral …


Should Fish Feel Pain? A Plant Perspective, František Baluška Jan 2016

Should Fish Feel Pain? A Plant Perspective, František Baluška

Animal Sentience

Key (2016) claims fish that fish do not feel pain because they lack the necessary neuronal architecture: their responses to noxious stimuli, according to Key, are executed automatically without any feelings. However, as pointed out by many of his commentators, this conclusion is not convincing. Plants might provide some clues. Plants are not usually thought to be very active behaviorally, but the evidence suggests otherwise. Moreover, in stressful situations, plants produce numerous chemicals that have painkilling and anesthetic properties. Finally, plants, when treated with anesthetics, cannot execute active behaviors such as touch-induced leaf movements or rapid trap closures after localizing …


Mediating Claims Through Critical Anthropomorphism, Gordon Burghardt Jan 2016

Mediating Claims Through Critical Anthropomorphism, Gordon Burghardt

Animal Sentience

Key’s (2016) discussion of his claim that fish do not feel pain ignores the history of attempts to study the attribution of mental states to other species. Although willing to accept that mammals feel pain, Key claims that fish lack the mammalian neural mechanisms underlying pain and are unconscious of their experiences. Consequently, we do not need to be overly concerned about fishing practices that would otherwise be viewed as painful. Key uses a flawed anthropomorphic lens. All attributions of mental events to organisms other than oneself involve inferences derived from anthropomorphic processes through which we process physiological and behavioral …


Where Is Pain In The Brain?, Marshall Devor Jan 2016

Where Is Pain In The Brain?, Marshall Devor

Animal Sentience

Key argues that fish cannot experience pain based on (1) brain imaging in humans, (2) consequences of lesions and (3) direct brain stimulation. Imaging indeed shows that pain-relevant signals reach the cortex, but not that they underlie the subjective experience of pain. Lesions and stimulation data are more to the point, but Key paints an idiosyncratic and misleading picture of their effects. S1 and S2 ablation does not eliminate evoked or spontaneous pain, although there may be up- or down-modulation. Likewise, stimulation of pain-associated cortical areas rarely induces pain, and pain almost never occurs at the onset of epileptic seizures. …


Why Fish Do Not Feel Pain, Brian Key Jan 2016

Why Fish Do Not Feel Pain, Brian Key

Animal Sentience

Only humans can report feeling pain. In contrast, pain in animals is typically inferred on the basis of nonverbal behaviour. Unfortunately, these behavioural data can be problematic when the reliability and validity of the behavioural tests are questionable. The thesis proposed here is based on the bioengineering principle that structure determines function. Basic functional homologies can be mapped to structural homologies across a broad spectrum of vertebrate species. For example, olfaction depends on olfactory glomeruli in the olfactory bulbs of the forebrain, visual orientation responses depend on the laminated optic tectum in the midbrain, and locomotion depends on pattern generators …


Fish Lack The Brains And The Psychology For Pain, Stuart W.G. Derbyshire Jan 2016

Fish Lack The Brains And The Psychology For Pain, Stuart W.G. Derbyshire

Animal Sentience

Debate about the possibility of fish pain focuses largely on the fish’s lack of the cortex considered necessary for generating pain. That view is appealing because it avoids relatively abstract debate about the nature of pain experience and subjectivity. Unfortunately, however, that debate cannot be entirely avoided. Subcortical circuits in the fish might support an immediate, raw, “pain” experience. The necessity of the cortex only becomes obvious when considering pain as an explicitly felt subjective experience. Attributing pain to fish only seems absurd when pain is considered as a state of explicit knowing.


A Single Strand Of Argument With Unfounded Conclusion, Robert W. Elwood Jan 2016

A Single Strand Of Argument With Unfounded Conclusion, Robert W. Elwood

Animal Sentience

Key (2016) describes the neural system involved in human pain experience in an excellent fashion but then suggests that only that complete system can generate the experience of pain. Thus animals without all components will not feel pain. This argument has been refuted in the past by analogy to vision where it is clear that a broad range of taxa, vertebrate and invertebrate, have good visual abilities albeit with completely different central nervous systems and receptors. This known counterargument to Key’s main idea is not mentioned in the target article. Further criteria that might indicate pain and studies examining these …


Pain And Fish Welfare, Eliane Gonçalves-De-Freitas Jan 2016

Pain And Fish Welfare, Eliane Gonçalves-De-Freitas

Animal Sentience

The evolutionary approach of Key’s (2016) target article, generically comparing humans with fish of all kinds, is simplistic. The author ignores published research on structural and molecular aspects of pain in fish. The target article reads more like a selective polemic against fish welfare than an even-handed analysis.


Fish Pain: An Inconvenient Truth, Culum Brown Jan 2016

Fish Pain: An Inconvenient Truth, Culum Brown

Animal Sentience

Whether fish feel pain is a hot political topic. The consequences of our denial are huge given the billions of fish that are slaughtered annually for human consumption. The economic costs of changing our commercial fishery harvest practices are also likely to be great. Key outlines a structure-function analogy of pain in humans, tries to force that template on the rest of the vertebrate kingdom, and fails. His target article has so far elicited 34 commentaries from scientific experts from a broad range of disciplines; only three of these support his position. The broad consensus from the scientific community is …


Pain And Other Feelings In Humans And Animals, Antonio Damasio, Hanna Damasio Jan 2016

Pain And Other Feelings In Humans And Animals, Antonio Damasio, Hanna Damasio

Animal Sentience

Evidence from neuroanatomy, neurophysiology, and neuropsychology suggests that the experience of feelings in humans does not depend exclusively on structures of the cerebral cortex. It does not seem warranted to deny the possibility of feeling in animals on the grounds that their cerebral cortices are not comparable to those of humans.


Fish Pain: Would It Change Current Best Practice In The Real World?, B. K. Diggles Jan 2016

Fish Pain: Would It Change Current Best Practice In The Real World?, B. K. Diggles

Animal Sentience

Much of the “fish pain debate” relates to how high the bar for pain should be set. The close phylogenetic affinities of teleosts with cartilaginous fishes which appear to lack nociceptors suggests caution should be applied by those who seek to lower the bar, especially given the equivocal and conflicting nature of the experimental data currently available for teleosts. Nevertheless, even if we assume fish “feel pain,” it is difficult to see how current best practice in aquaculture would change. This is because of the need to avoid stress at all stages of the rearing process to optimize health, growth …


Leaving The Door Open For Fish Pain: Evolutionary Convergence And The Utility Of ‘Just-So Stories’, David B. Edelman Jan 2016

Leaving The Door Open For Fish Pain: Evolutionary Convergence And The Utility Of ‘Just-So Stories’, David B. Edelman

Animal Sentience

Key argues that fish do not experience pain because they lack the necessary (but not necessarily sufficient) brain structures and associated functional circuitry to engender such conscious percepts. I propose that fish pain may be dependent on neuroanatomical regions and pathways that are structurally and/or functionally analogous — but not strictly homologous — to well-characterized mammalian substrates of pain. An example is the convergent appearance of the complex, single-compartment eye across invertebrate and vertebrate phylogeny. Structural-functional convergence is ubiquitous in evolution. Comparative inferences and correlative lines of evidence play an important role in building evolutionary arguments. The dismissal of the …


Pain-Capable Neural Substrates May Be Widely Available In The Animal Kingdom, Edgar T. Walters Jan 2016

Pain-Capable Neural Substrates May Be Widely Available In The Animal Kingdom, Edgar T. Walters

Animal Sentience

Neural and behavioral evidence from diverse species indicates that some forms of pain may be generated by coordinated activity in networks far smaller than the cortical pain matrix in mammals. Studies on responses to injury in squid suggest that simplification of the circuitry necessary for conscious pain might be achieved by restricting awareness to very limited information about a noxious event, possibly only to the fact that injury has occurred, ignoring information that is much less important for survival, such as the location of the injury. Some of the neural properties proposed to be critical for conscious pain in mammals …


How Not To Move The Line Drawn On Pain, Bjorn H. Merker Jan 2016

How Not To Move The Line Drawn On Pain, Bjorn H. Merker

Animal Sentience

In this second commentary I outline the inadequacy of Key's responses to the many peer critiques of his thesis that have so far appeared in Animal Sentience. I illustrate with examples drawn from his response to my first commentary.


Spinning Our Wheels And Deepening The Divide: Call For An Evidence-Based Approach To The Fish Pain Debate, Steven J. Cooke Jan 2016

Spinning Our Wheels And Deepening The Divide: Call For An Evidence-Based Approach To The Fish Pain Debate, Steven J. Cooke

Animal Sentience

There is vigorous ongoing debate about whether fish feel pain and have the capacity to suffer. The body of literature dedicated to the topic is increasing but what is particularly problematic is that the majority of the contributions represent opinion pieces and thus fall within the realm of advocacy. Many of the empirical research papers purporting that fish do or do not feel pain have problems with cavalier use of definitions, poor experimental design, or statistical/technical issues and tend to include advocacy statements in their interpretations. Rather than continuing to spin our wheels and deepen the divide, I would advocate …


Pain In Parallel, Peter Godfrey-Smith Jan 2016

Pain In Parallel, Peter Godfrey-Smith

Animal Sentience

Key's (2016) arguments against the view that fish feel pain can be shown to be fallacious by considering some damage-related behaviors in invertebrates. Pain may have different neural bases in different organisms, so the absence in fish of the cortical structures that might underlie pain in mammals does not settle the question of fish pain.


Pain In Fish: Weighing The Evidence, James D. Rose Jan 2016

Pain In Fish: Weighing The Evidence, James D. Rose

Animal Sentience

The target article by Key (2016) examines whether fish have brain structures capable of mediating pain perception and consciousness, functions known to depend on the neocortex in humans. He concludes, as others have concluded (Rose 2002, 2007; Rose et al. 2014), that such functions are impossible for fish brains. This conclusion has been met with hypothetical assertions by others to the effect that functions of pain and consciousness may well be possible through unknown alternate neural processes. Key's argument would be bolstered by consideration of other neurological as well as behavioral evidence, which shows that sharks and ray are fishes …


Nonverbal Indicators Of Pain, Simon Van Rysewyk Jan 2016

Nonverbal Indicators Of Pain, Simon Van Rysewyk

Animal Sentience

In discussing fish pain, Key (2016) privileges pain in humans — “the only species able to directly report on its feelings.” Human experience of pain is not necessarily best reflected by verbal self-report, however. Neural responses to noxious stimuli are influenced by individual differences and by context. Nonverbal pain displays such as facial expressions reflect part of the neural response to noxious stimuli. Most mammals have a specific facial grimace reflecting pain. If fish have a somatic expression of pain, the development of a reliable and accurate somatic pain scale specific to fish could make a contribution to the debate …


Anthropomorphic Denial Of Fish Pain, Lynne U. Sneddon, Matthew C. Leach Jan 2016

Anthropomorphic Denial Of Fish Pain, Lynne U. Sneddon, Matthew C. Leach

Animal Sentience

Key (2016) affirms that we do not know how the fish brain processes pain but denies — because fish lack a human-like cortex — that fish can feel pain. He affirms that birds, like fish, have a singly-laminated cortex and that the structure of the bird brain is quite different from that of the human brain, yet he does not deny that birds can feel pain. In this commentary we describe how Key cites studies that substantiate mammalian pain but discounts the same kind of data as evidence of fish pain. We suggest that Key's interpretations are illogical, do not …


Going Beyond Just-So Stories, Brian Key Jan 2016

Going Beyond Just-So Stories, Brian Key

Animal Sentience

Colloquial arguments for fish feeling pain are deeply rooted in anthropometric tendencies that confuse escape responses to noxious stimuli with evidence for consciousness. More developed arguments often rely on just-so stories of fish displaying complex behaviours as proof of consciousness. In response to commentaries on the idea that fish do not feel pain, I raise the need to go beyond just-so stories and to rigorously analyse the neural circuitry responsible for specific behaviours using new and emerging technologies in neuroscience. By deciphering the causal relationship between neural information processing and conscious behaviour, it should be possible to assess cogently the …


Falsifying The Null Hypothesis That “Fish Do Not Feel Pain", Brian Key Jan 2016

Falsifying The Null Hypothesis That “Fish Do Not Feel Pain", Brian Key

Animal Sentience

The reader of Animal Sentience may surmise that because the weight of the commentaries on my target article, “Why fish do not feel pain,” is leaning towards not supporting my argument, it follows that the premise "fish do not feel pain" is incorrect. However, science does not prevail by popular opinion. History is plagued with numerous (and often widely accepted) examples of biological phenomena being explained by mysterious forces. In the absence of a mechanistic understanding, the many different guises of vitalism (the principle that life involves a vital energy) are often invoked to explain the unknown. Spurious …


An Invertebrate Perspective On Pain, Jennifer A. Mather Jan 2016

An Invertebrate Perspective On Pain, Jennifer A. Mather

Animal Sentience

Although Key (2016) argues that mammals feel pain and fish do not, from an invertebrate perspective, it is obvious that the pain experience is shared by animals from a number of different animal groups.


Sentience And Animal Welfare: New Thoughts And Controversies, Donald M. Broom Jan 2016

Sentience And Animal Welfare: New Thoughts And Controversies, Donald M. Broom

Animal Sentience

Sentience involves having some degree of awareness but awareness of self is not as complex as some people believe. Fully functioning vertebrate animals, and some invertebrates, are sentient but neither humans nor non-humans are sentient early in development or if brain-damaged. Feelings are valuable adaptive mechanisms and an important part of welfare but are not all of welfare so the term welfare refers to all animals, not just to sentient animals. We have much to learn about what non-human animals want from us, the functioning of the more complex aspects of their brains and of our brains and how we …


Cortex Necessary For Pain — But Not In Sense That Matters, Adam J. Shriver Jan 2016

Cortex Necessary For Pain — But Not In Sense That Matters, Adam J. Shriver

Animal Sentience

Certain cortical regions are necessary for pain in humans in the sense that, at particular times, they play a direct role in pain. However, it is not true that they are necessary in the more important sense that pain is never possible in humans without them. There are additional details from human lesion studies concerning functional plasticity that undermine Key’s (2016) interpretation. Moreover, no one has yet identified any specific behaviors that mammalian cortical pain regions make possible that are absent in fish.


Why Is Fish “Feeling” Pain Controversial?, E. Don Stevens Jan 2016

Why Is Fish “Feeling” Pain Controversial?, E. Don Stevens

Animal Sentience

In his excellent target article, Key (2016) develops a mechanistic argument in an attempt to show why it is unlikely that fish can “feel” pain or for that matter, “feel” anything. The topic is controversial and likely to achieve the goal of getting many hits for the inaugural issue of the new journal, Animal Sentience. In my view, the question is unlikely to be answered, for two reasons. First, because the proponents of the “fish feel pain” controversy are untrained and unskilled in the details and jargon of neurophysiology and/or neuroanatomy, and the opponents of the controversy, like Key, …


Fish Pain: A Painful Topic, Carl Safina Jan 2016

Fish Pain: A Painful Topic, Carl Safina

Animal Sentience

If fish cannot feel pain, why do stingrays have purely defensive tail spines that deliver venom? Stingrays’ ancestral predators are fish. And why do many fishes possess defensive fin spines, some also with venom that produces pain in humans? These things did not evolve just in case sentient humans would evolve millions of years later and then invent scuba. If fish react purely unconsciously to “noxious” stimuli, why aren’t sharp jabbing spines enough? Why also stinging venom?


How Welfare Biology And Commonsense May Help To Reduce Animal Suffering, Yew-Kwang Ng Jan 2016

How Welfare Biology And Commonsense May Help To Reduce Animal Suffering, Yew-Kwang Ng

Animal Sentience

Welfare biology is the study of the welfare of living things. Welfare is net happiness (enjoyment minus suffering). Since this necessarily involves feelings, Dawkins (2014) has suggested that animal welfare science may face a paradox, because feelings are very difficult to study. The following paper provides an explanation for how welfare biology could help to reduce this paradox by answering some difficult questions regarding animal welfare. Simple means based on commonsense could reduce animal suffering enormously at low or even negative costs to humans. Ways to increase the influence of animal welfare advocates are also discussed, focusing initially on farmed …


Is Sentience Only A Nonessential Component Of Animal Welfare?, Ian J.H. Duncan Jan 2016

Is Sentience Only A Nonessential Component Of Animal Welfare?, Ian J.H. Duncan

Animal Sentience

According to Broom (2014), animal welfare is a concept that can be applied to all animals, including single-celled organisms that are obviously not sentient. Such a stance makes it difficult to draw a connection between welfare and sentience, and that is the book’s downfall. Some excellent points are made about sentience and there are very good discussions on animal welfare. However, unless sentience is considered the essential component of welfare, any attempt to link the two phenomena will be unsuccessful — and that, indeed, is the case with this book.


Why Animal Welfarism Continues To Fail, Lori Marino Jan 2016

Why Animal Welfarism Continues To Fail, Lori Marino

Animal Sentience

Welfarism prioritizes human interests over the needs of nonhuman animals. Despite decades of welfare efforts other animals are mostly worse off than ever before, being subjected to increasingly invasive and harmful treatments, especially in the factory farming and biomedical research areas. A legal rights-based approach is essential in order for other animals to be protected from the varying ethical whims of our species.