A statistical analysis of the intercuspal angle of the phragmodontiform element of Phragmodus undatus

The intercuspal angle of the phragmodontiform element of the conodont Phragmodus undatus Branson and Mehl, 1933 was measured on specimens from samples from two cores drilled in the Cincinnati Region. In the section studied from the core from Minerva, Kentucky, a general trend can be observed that suggests a decrease in the mean intercuspal angle of the population with time. That trend correlates to a similar decrease in the relative abundance of P. undatus, which suggests a general shallowing of the water column. The section studied from the core from New Point, Indiana correlates to the upper part of the section studied from the core from Minerva, Kentucky, and extends stratigraphically higher. That section represents relatively deeper water, in which the mean intercuspal angle of the P. undatus population does not significantly differ with time. This suggests that a period of stasis developed during which P. undatus was in general equilibrium with paleoenvironmental factors as controlled by relative water depth.No embarg

Bacteria and the cellular basis of consciousness

According to Reber’s theory, the Cellular Basis of Consciousness (CBC), sentience originates as bio-sensitivity in unicellular organisms. For this reason, Reber regards sentience as evolutionarily foundational. Many bacteria show chemotaxis and, thus, according to CBC, they are sentient. Analysis of the genetic mechanisms underlying bacterial chemotaxis indicates that sentience has no explanatory power in this case. Genetic analysis also fails to show species continuity underlying bio-sensitivity in bacteria and bio-sensitivity in species with nervous systems, so it does not seem that sentience is evolutionary foundational. CBC is rejected on these grounds

The fish in the creek is sentient, even if I can’t speak with it

In this paper I argue that Velmens’ reflexive model of perceptual consciousness is useful for understanding the first-person perspective and sentience in animals. I then offer a defense of the proposal that ray-finned bony fish have a first-person perspective and sentience. This defense has two prongs. The first prong is presence of a substantial body of evidence that the neuroanatomy of the fish brain exhibits basic organizational principles associated with consciousness in mammals. These principles include a relationship between a second-order sensory relay, the preglomerular complex, and the fish pallium which bears a resemblance to the relationship between the mammalian thalamus and the neocortex, the existence of feedback/feedforward and reentrant circuitry in the pallium, and structural and functional differences among divisions of the fish pallium. The second prong is the existence of behaviors in fish that exhibit significant flexibility in the presence of environmental change and require relational learning among stimuli distributed in space, over time, or both. I conclude that, although they are instantiated differently, a first-person perspective and sentience are present in fish

Pain in fish: Evidence from peripheral nociceptors to pallial processing

The target article by Sneddon et al. (2018) presents convincing behavioral and pharmacological evidence that ray-finned fish consciously perceive noxious stimuli as painful. One objection to this interpretation of the evidence is that the fish nervous system is not complex enough to support the conscious experience of pain. Data that contradict this objection are presented in this commentary. The neuroanatomy and neurophysiology of the fish nervous system from the peripheral nerves to the pallium is able to support the sentient appreciation of pain

Sentience in fishes: More on the evidence

In my target article, I argued that the brains of ray-finned fishes of the teleost subclass (Actinopterygii) are sufficiently complex to support sentience — that these fishes have subjective awareness of interoceptive and exteroceptive sense experience. Extending previous theories centered on the tectum, I focused on the organization of the fish pallium. In this Response to the commentaries, I clarify that I do not propose that the fish pallium is, or must be, homologous to the mammalian neocortex to play a role in sentience. Some form of a functionalist approach to explaining the neural basis of sentience across taxa is probably most appropriate. However, what is known about the neural correlates of consciousness in humans is adequate to provide a starting place for investigation of the correlates of sentience in other animals, including fishes. Ultimately, though, hypotheses and experiments to evaluate anatomical and physiological correlates specific to sentience in fishes will be necessary

Whether invertebrates are sentient matters to bioethics and science policy

Mikhalevich & Powell provide convincing empirical evidence that at least some invertebrates are sentient and hence should be granted moral status. I agree and argue that functional markers should be the primary indicators of sentience. Neuroanatomical homologies provide only secondary evidence. Consensus regarding the validity of these functional markers will be difficult to achieve. To be effective in practice, functional markers of sentience will have to be tested and accepted species by species to overcome the implicit biases against extending moral status to invertebrates

Scientific uncertainty and the animal sentience precautionary principle

Jonathan Birch offers the animal sentience precautionary principle (ASPP) as a framework for assigning sentience to animals. In doing this, he defines a BAR which when crossed will lead to action (ACT) and implementation of the ASPP. His effort to create a clear empirical basis for implementation of the precautionary principle in the area of animal welfare regulation is important. I argue, however, that his BAR is so low that the evidence supporting ACT is in danger of being overwhelmed by the problems of induction and the underdetermination of theory by evidence. If this happens, policy makers might well disregard the ASPP and fail to include sentient species in animal welfare regulation. I suggest that the BAR needs to be raised by inclusion of more independent indicators of sentience than those required by Birch

Sentience is the foundation of animal rights

Chapman & Huffman argue that the cognitive differences between humans and nonhuman animals do not make humans superior to animals. I suggest that humans have domain-general cognitive abilities that make them superior in causing uniquely complex changes in the world not caused by any other species. The ability to conceive of and articulate a claim of rights is an example. However, possession of superior cognitive ability does not entitle humans to superior moral status. It is sentience, not cognitive complexity, that is the basis for the assignment of rights and the protections under the law that accompany them

Implicit mental processes are an improbable basis for personhood

Rowlands argues that animals have implicit pre-reflective awareness and that this is adequate to create the unity of conscious thought required for personhood. For him pre-reflective awareness does not include intentionality and is probably an unconscious process. I suggest that his sense of implicit leads to significant difficulties for his argument and that including intentionality in the definition of a first-person perspective provides a stronger base for viewing animals as persons

Consciousness in teleosts: There is something it feels like to be a fish

Ray-finned fish are often excluded from the group of non-human animals considered to have phenomenal consciousness. This is generally done on the grounds that the fish pallium lacks a sufficiently expansive gross parcellation, as well as even minimally sufficient neuronal organization, intrinsic connectivity, and reciprocal extrinsic connections with the thalamus to support the subjective experience of qualia. It is also argued that fish do not exhibit the level of behavioral flexibility indicative of consciousness. A review of neuroanatomical, neurophysiological and behavioral studies is presented which leads to the conclusion that fish do have neurobiological correlates and behavioral flexibility of sufficient complexity to support the hypothesis that they are capable of phenomenal consciousness