What is ‘sentience’ in animals and why does it matter? 

Sentience means the ability to have experiences. A sentient animal can feel things, not just physical sensations like heat or pain, but also internal states such as comfort, fear, curiosity or pleasure. You don’t need to have language, complex thoughts, or human-like reasoning to be sentient. A being can be sentient even if it can’t talk, it doesn’t understand its emotions, or it experiences the world very differently from us. 

Sentience is simply the capacity to feel, experience, and be aware in some way. That’s what makes it morally important. When a creature can suffer or enjoy life, its welfare matters. 

We say our dog “knows” we’re sad, or that a crow is “clever”, or that an octopus seems “curious”. But beneath these everyday intuitions lies a deeper, far more challenging question: what does it really mean for a creature to be sentient? 

And more importantly, why does it matter that we answer this question well? 

Today, sentience is no longer just a philosophical puzzle. It shapes how we understand the natural world, how we care for the beings we share it with, and more and more, how we design laws and policies that affect millions of animals every day. From dogs and chickens to octopuses and even insects, the science of sentience is expanding faster than ever, raising profound questions about ethics, welfare, and what it means to be alive. 

This article explores the idea of sentience, where the science is heading, and how governments like the UK are responding to it. 

Insect sentience: A radical frontier? 

For decades, most scientists (and most laws) assumed insects were too simple to be sentient. Their tiny brains seemed incapable of subjective experience. They were thought to behave purely on instinct, like tiny automatons. 

But over the past decade or so, that assumption has been eroded by a steady stream of astonishing research. 

Research has shown that species like bees, fruit flies, and ants demonstrate optimism or pessimism depending on previous experiences. They also show motivational trade-offs, weighing risks and rewards in ways similar to vertebrates. It has been found that they may change their behaviour after injury in ways consistent with pain modulation, solve novel problems and learn tool use, and even exhibit play-like behaviours (bumblebees rolling tiny balls appears to be just for fun)! 

Some scientists argue this suggests at least a low-level form of sentience. Others caution that these behaviours could arise without consciousness at all. 

Still, this all begs the question, if an insect acts as though it can suffer, how certain must we be before we change how we treat it? 

This question has huge implications. If insects are sentient, then industrial insect farming (already scaling rapidly) becomes ethically fraught. Pest-control methods may require rethinking, conservation policy could expand dramatically, and our entire moral circle might need widening. 

We may be entering a future where the moral landscape includes not only mammals and birds, but perhaps hundreds of thousands of species of tiny, intricate beings. 

Sentience beyond brains 

Another challenge is that sentience may not require a brain like ours. Octopuses have a distributed nervous system, with many neurons in their arms. Jellyfish exhibit complex behaviours without a central brain. Some worms show learning despite having extremely simple neural circuits. 

Could subjective experience arise from these systems? We don’t know. And that uncertainty itself is important. 

Scientists are increasingly using computational models, neural architecture comparisons, and behavioural studies to explore how widespread sentience might be. Some even propose that sentience is more like a spectrum than a binary. Many animals may have limited but genuine forms of feeling. 

This raises the unnerving but exciting possibility that sentience might be far more common than we ever imagined… Possibly even extending to plants (which have a complex electric system not dissimilar in structure to a distributed nervous system). 

Why science alone can’t solve it 

These are not purely scientific questions. They blend biology, ethics, psychology, and public values. But they are questions we increasingly need to confront. 

Why does sentience matter to us, practically? 

Recognising animal sentience forces us to rethink our relationship with other species in every sphere of life. 

In farming, this may include considering how we house, handle, and kill animals. This must consider not just physical health but psychological wellbeing. As evidence grows for cognitive capacities in animals like chickens, pigs, and fish, welfare standards should continue to rise. 

In conservation, protecting sentient animals isn’t just about preserving species. It’s about alleviating suffering. When invasive species must be culled, for example, humane methods matter. 

Regulations often require minimising distress in lab animals. Expanding the category of animals likely to be sentient could reshape research practices. 

And in everyday life, from how we treat garden wildlife to the ethics of keeping pets, recognising sentience encourages empathy and responsibility. 

How wide do we want our circle of care to be? 

Sentience pushes us toward one of the most profound questions of the 21st century: Who gets to matter? 

As scientific evidence accumulates, we are discovering that many animals once dismissed as simple or insensate may have rich, meaningful lives of their own. Whether it’s a pig showing empathy, a crow solving a puzzle that would challenge a child, or a bumblebee appearing to play, each new insight invites us to expand our moral imagination. 

Perhaps the real challenge is not determining which animals are sentient but deciding how far we are willing to extend compassion when the answer is uncertain.