How many senses do humans have? Five would be the logical answer: sight, hearing, smell, taste and touch. But what if there were other ways to perceive the world, ways we can barely imagine and beyond what we think would lie within the realm of possibility? In Sentient: What Animals Reveal About Our Senses, Jackie Higgins’ debut book, the accomplished zoologist and filmmaker shows how many different ways living beings can interact with and understand the natural world, through the eyes of the animals we humans share it with. 

From the magnificent cheetah to the ingenious common octopus, and many other wonderful creatures in between, Higgins shows us exactly what the animal world can teach us about how we perceive our surroundings and our reality.

Sentient opens with a straightforward but far from simple question, what does it mean to be sentient? For Higgins, any creature who can sense their surroundings, who can employ one of their senses and build a conscious narrative around the reality they inhabit, is a sentient being.

As it turns out, there are many more ways that living beings can understand their world, possibly in the dozens, but for a number of reasons, humans have conceptually limited ourselves to five. Our connection to five senses has been something we have been tied to for millennia, and Higgins does a fantastic job explaining why we are still in the grip of this somewhat limited view of our senses.

But the truth is, our senses may number in the dozens. The ways our skin, eyes, nose, tongue and ears contextualise our world in ways we can barely discern. Our eyes, for instance, are not only capable of perceiving space but also time. Our ears are good at picking up sounds, but also work to keep us balanced. We can perceive our world in so many wonderful ways that we barely pay attention to, so Higgins artfully shows us the animals that have mastered these deeper senses of perception.

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Chapter by chapter, Higgins takes us on a memorable journey through the unique and delightful world of our hidden and unknown senses, shown through the eyes of several wonderful creatures. Some of these senses are ones we don’t know we have, and others are ones that we know we have, but may have never given them much thought.

The sense of proprioception for instance, our perception of our body and movements, is what helps us stay aware of where our fingers, hands, feet and limbs are at any given time. It is what gives us the ability to automatically balance ourselves when we walk, to navigate unfamiliar terrain and to instinctively shoot our hands and arms forwards to stop our fall after we trip over a rock. This ‘sixth sense’ does not factor into our common catalogue of six senses, but nevertheless gives us the ability to automatically balance our muscles and body to handle everyday tasks.

Should this sense be taken away from us, as Higgins documents in one gripping narrative towards the end of the book, our lives would be completely different and cumbersome, as even the simple act of walking down the street becomes an incredibly arduous task. 

But it is by examining the behaviour of other animals who have mastered the sense of proprioception that we are able to understand how to expand and enrich our sensorial capabilities. In this case, Higgins delves into the wondrous world of the common octopus, who seems to be in proprioceptive control of its many limbs, which simultaneously seem to have a mind of their own. In a wonderfully related instance of the intricate delights of animal senses, humans can understand how our own efforts to overcome an apparent loss of sense are being uniquely mirrored in the animal world.

We can learn so much from animals, and we can do so in ways that improve our quality of life while also paying it all back to the animal world. These animals are only able to function and interact with their surroundings because of the ecological niches they have evolved in and become attuned to. By protecting these wilds and allowing the natural world to continue thriving, there is no end to how much we can learn from our living companions.

Check out Earth.Org’s fascinating video conversation with Jackie here.

Sentient: What Animals Reveal about our Senses
Jackie Higgins
2021, Pan Macmillan, 344pp