The sentience shift in animal research

Debates on humanization of human-animal brain chimeras - are we putting the cart before the horses?

Research on human-animal chimeras have elicited alarms and prompted debates. Those involving the generation of chimeric brains, in which human brain cells become anatomically and functionally intertwined with their animal counterparts in varying ratios, either via xenografts or embryonic co-development, have been considered the most problematic. The moral issues stem from a potential for "humanization" of the animal brain, as well as speculative changes to the host animals' consciousness or sentience, with consequential alteration in the animal hosts' moral status. However, critical background knowledge appears to be missing to resolve these debates. Firstly, there is no consensus on animal sentience vis-à-vis that of humans, and no established methodology that would allow a wholesome and objective assessment of changes in animal sentience resulting from the introduction of human brain cells. Knowledge in interspecies comparative neuropsychology that could allow effective demarcation of a state of "humanization" is also lacking. Secondly, moral status as a philosophical construct has no scientific and objective points of reference. Either changes in sentience or humanization effects would remain unclear unless there are some neuroscientific research grounding. For a bioethical stance based on moral status of human-animal brain chimera to make meaningful contributions to regulatory policies, it might first need to be adequately informed by, and with its arguments constructed, in a manner that are factually in line with the science. In may be prudent for approved research projects involving the generation of human-animal brain chimera to have a mandatory component of assessing plausible changes in sentience.

Introducing individual sentience profiles in nonhuman primate neuroscience research

The Animal Research Declaration is committed to establishing cohesive and rigorous ethical standards to safeguard the welfare of nonhuman primates (NHPs) engaged in neuroscience research (Petkov et al., 2022 this issue). As part of this mission, there is an expanding dialogue amongst neuroscientists, philosophers, and policymakers, that is centred on diverse aspects of animal welfare and scientific practice. This paper emphasises the necessity of integrating the assessment of animal sentience into the declaration. Animal sentience, in this context, refers to the recognized capacity that animals have for various kinds of subjective experience, with an associated positive or negative valence (Browning and Birch, 2022). Accordingly, NHP neuroscience researchers should work toward instituting a standardised approach for evaluating what can be termed "individual sentience profiles," representing the unique manner in which an individual NHP experiences specific events or environments. The adoption of this novel parameter would serve a triad of indispensable purposes: enhancing NHP welfare throughout research involvement, elevating the quality of life for NHPs in captivity, and refining the calibre of research outcomes.

Optimism about Measuring Animal Feelings

While animal sentience research has flourished in the last decade, scepticism about our ability to accurately measure animal feelings has unfortunately remained fairly common. Here, we argue that evolutionary considerations about the functions of feelings will give us more reason for optimism and outline a method for how this might be achieved.

Research Animal Behavioral Management Programs for the 21st Century

Behavioral management programs have been developed commonly for research dogs and primates but rarely has program consideration been expanded to include all research species worked with. This is necessary to reduce animal stress and promote natural behaviors, which can promote good animal welfare and result in more robust and reproducible scientific data. We describe the evolution of consideration for research animal needs and define an umbrella-based model of research animal behavioral management programs, which may be used for all research species. In addition to developing a more comprehensive program, we emphasize the need for regular welfare assessments to determine whether the program is working cohesively and whether any aspects require modification.

Why the Epistemic Objection Against Using Sentience as Criterion of Moral Status is Flawed

According to a common view, sentience is necessary and sufficient for moral status. In other words, whether a being has intrinsic moral relevance is determined by its capacity for conscious experience. The epistemic objection derives from our profound uncertainty about sentience. According to this objection, we cannot use sentience as a criterion to ascribe moral status in practice because we won't know in the foreseeable future which animals and AI systems are sentient while ethical questions regarding the possession of moral status are urgent. Therefore, we need to formulate an alternative criterion. I argue that the epistemic objection is dissolved once one clearly distinguishes between the question what determines moral status and what criterion should be employed in practice to ascribe moral status. Epistemic concerns are irrelevant to the former question and-I will argue-criteria of moral status have inescapably to be based on sentience, if one concedes that sentience determines moral status. It follows that doubts about our epistemic access to sentience cannot be used to motivate an alternative criterion of moral status. If sentience turns out to be unknowable, then moral status is unknowable. However, I briefly advocate against such strong pessimism.