Welfare-aligned Sentience: Enhanced Capacities to Experience, Interact, Anticipate, Choose and Survive

Simple Summary Formal recognition that some animals are sentient beings is now widespread and continues to increase internationally. Sentience is a capacity of animals to consciously perceive by the senses; to consciously feel or experience subjectively. In animals that manifest different states of welfare, these experiences can be negative, that is, potentially welfare compromising, or positive, that is, potentially welfare enhancing. As there have been significant advances during the last two decades in the science that underpins our understanding of sentience, the major purpose here is to provide up-to-date perspectives on that understanding. Thus, the present focus is on the key features of sentience in animals which can experience different states of welfare, encapsulated by the new term 'welfare-aligned sentience'. This term is intended to exclude potential forms of sentience that do not enable animals in some taxa to have the subjective experiences which underlie different welfare states. The approach adopted is to present 11 interconnected statements about sentience-associated body functions and behaviour, and to explain them in largely non-technical language. Topics covered include the following: The characteristics of nervous systems required for welfare-aligned sentience to be expressed and how those characteristics develop in young animals; the importance of sensory inputs from inside the body and from outside the body and their roles in generating particular sensations, feelings, emotions and other subjective experiences; how these experiences elicit behaviours that help the animal to survive, and are also key elements in animals' communication with others and their interactions with the environment. The following are also considered: How this new scientific knowledge helps to circumvent some acknowledged pitfalls of anthropomorphism when making inferences about the particular subjective experiences that animals may have; and the possible inclusion of more invertebrates among the list of animals that possess a capacity for sentience-a list which, to date, has been dominated by vertebrates. In addition, it is noted that the earlier assessment of the presence or absence of sentience by predominantly exploring responses to potentially aversive experiences such as pain, needs to be revised. Such assessments should also include sentient animals' capacities to have and behaviourally express positive subjective experiences. Finally, the following succinct definition is offered for consideration: Welfare-aligned sentience confers a capacity to consciously perceive negative and/or positive sensations, feelings, emotions or other subjective experiences which matter to the animal. The focus of this opinion is on the key features of sentience in animals which can experience different states of welfare, encapsulated by the new term 'welfare-aligned sentience'. This term is intended to exclude potential forms of sentience that do not enable animals in some taxa to have the subjective experiences which underlie different welfare states. As the scientific understanding of key features of sentience has increased markedly during the last 10 to 15 years, a major purpose here is to provide up-to-date information regarding those features. Eleven interconnected statements about sentience-associated body functions and behaviour are therefore presented and explained briefly. These statements are sequenced to provide progressively more information about key scientifically-supported attributes of welfare-aligned sentience, leading, in their entirety, to a more comprehensive understanding of those attributes. They are as follows: (1) Internal structure-function interactions and integration are the foundations of sentience; (2) animals posess a capacity to respond behaviourally to a range of sensory inputs; (3) the more sophisticated nervous systems can generate subjective experiences, that is, affects; (4) sentience means that animals perceive or experience different affects consciously; (5) within a species, the stage of neurobiological development is significant; (6) during development the onset of cortically-based consciousness is accompanied by cognitively-enhanced capacities to respond behaviourally to unpredictable postnatal environments; (7) sentience includes capacities to communicate with others and to interact with the environment; (8) sentience incorporates experiences of negative and positive affects; (9) negative and positive affective experiences 'matter' to animals for various reasons; (10) acknowledged obstacles inherent in anthropomorphism are largely circumvented by new scientific knowledge, but caution is still required; and (11) there is increasing evidence for sentience among a wider range of invertebrates. The science-based explanations of these statements provide the foundation for a brief definition of 'welfare-aligned sentience', which is offered for consideration. Finally, it is recommended that when assessing key features of sentience the same emphasis should be given to positive and negative affective experiences in the context of their roles in, or potential impacts on, animal welfare.