The Matter of Non-Avian Reptile Sentience, and Why It “Matters” to Them: A Conceptual, Ethical and Scientific Review

SIMPLE SUMMARY: Sentience is a complex and contentious concept, especially when attributing the label to non-human animals. Non-avian reptiles are often overlooked in many scientific, ethical and layperson discussions of sentience, awareness and consciousness in animals. Most modern declarations of sentience include all vertebrate animals, and some invertebrates, which automatically includes reptiles and fish. However, specific declarations often ignore the “lower” classes of non-human animals. This paper specifically focuses reviewing the concepts and definitions of consciousness, awareness and sentience; and then reviews research which provides solid evidence for sentience in non-avian reptiles. It is concluded that non-avian reptiles indeed possess all of the necessary capacities to be classified as sentient beings. ABSTRACT: The concept of sentience, how it is characterised and which non-human animals possess it have long been of contention in academic and intellectual debates. Many have argued that there is no way to empirically know that animals have conscious experiences. Yet others argue that consciousness, awareness and sentience in non-human animals can be quite obvious, and can indeed be measured empirically. Most modern declarations of animal sentience from official organisations and governments now include all vertebrate animals as sentient beings, including reptiles and fish. Some declarations also include some invertebrate species. This conceptual, ethical and scientific review first focuses on conceptual components and definitions of consciousness, awareness and sentience. It then specifically discusses how cognitive, neurobiological, ethological and comparative psychological research in non-avian reptiles over the last century has evidenced many capacities that historically were denied to this class of animals. Non-avian reptiles do indeed possess all of the necessary capacities to be declared as sentient beings, at least in the small proportion of reptile species that have actually been empirically investigated so far. It is suggested that much innovative future research will continue to uncover evidence of capabilities linked to sentience within a wide range of species, including non-avian reptiles, fish and invertebrates.