What is sentience?
Sentience is the ability to perceive one's environment, and experience sensations such as pain and suffering, or pleasure and comfort.1 An animal that is sentient will have the ability to receive internal sensation and information from its environment, and then interpret this as an emotion. The sensation may make it feel good, bad, or indifferent. It will determine how best to act based on this, and use responses in its body, or a behaviour, in order to fulfil its needs. Some species are also capable of more complex thought, such as reasoning , when making decisions about how to act.2 Of course, a lot of our responses to sensations are automatic.3 Imagine if you were thinking about how to make every step or coordinate every move in catching a ball! These types of unconscious actions and simple reflexes may be all that some species, such as worms, are capable of.
Discussions about sentience in animals started as far back as the Renaissance era, with people like Leonardo Da Vinci and even Shakespeare writing about these ideas.4 Many countries now acknowledge animal sentience, and animals' ability to experience pain, fear, distress, hunger and thirst, in their laws, which are designed to protect animals from such suffering. In 1997, the European Union agreed to recognise animals as 'sentient beings' under European law.5
Species generally acknowledged to be sentient include those with backbones, as well as octopus and squid, and crabs and lobsters.6 It may be that we discover sentience in other species as more and more research reveals animals' intelligence and emotions.
Regardless of the type of animal, our understanding of sentience means we must treat them in ways that avoid suffering and maximise well-being. As Jeremy Bentham, the English social reformer stated in 1823, "The question is not, Can they reason? nor, Can they talk? but, Can they suffer?"
It is a moral imperative that if in doubt, we must assume an animal feels pain and can suffer and, therefore, take action to avoid minimise or alleviate such pain and suffering.
1Animals, Ethics and Trade – The Challenge of Animal Sentience (2006) ed Turner, J and D'Silva, J, Earthscan, London
2Animals, Ethics and Trade – The Challenge of Animal Sentience (2006) ed Turner, J and D'Silva, J, Earthscan, London
3Chandroo, KP, Duncan, I and Moccia, RD (2004) Can ﬁsh suffer?: perspectives on sentience, pain, fear and stress, Applied Animal Behaviour Science, pg 225-250
4 Duncan, I (2006) The changing concept of animal sentience, Applied animal behaviour science, pg 11-19; Dawkins, MS (2006) Through animal eyes: What behaviour tells us, Applied Animal Behaviour Science, pg 1-7
6 Duncan, I (2006) The changing concept of animal sentience, Applied animal behaviour science, pg 11-19