by Ed Yong
Random House, 2023
In An Immense World, Pulitzer Prize–winning science journalist Ed Yong reveals entirely new ways to think about the world around us. Reading this mind-blowing account of animal evolution and behavior pushes us to imagine new dimensions, beyond the limits of what the human brain and body can do. Yong shows us that we and the myriad animal species that share our planet, or even the same room, live in completely different worlds.
Yong explores how animals, including humans, sense and perceive what is around them. By interviewing dozens of biological experts and getting surprisingly hands-on with some of their diverse research subjects, he describes the vanguard of research about how animals see, hear, touch, taste, smell, and otherwise experience our immense world. As Yong explains, Aristotle’s classification of the five senses didn’t go far enough. Animals also have internal senses of proprioception (awareness of body position and movement) and equilibrioception (sense of balance). Yong describes in fascinating detail several more senses that are beyond human experience, including magnetoreception, electroreception, and echolocation.
With vivid examples, Yong shows us that even the definition of each sense can be fuzzy. When treehoppers send and sense surface vibrations across a plant, does that count as sound or touch or both? When an octopus touches something, it both feels it and tastes it chemically with a sort of touch-taste sense.
A key concept in the book is the term umwelt, coined in 1909 by zoologist Jakob von Uexküll, to describe an animal’s sensory world – in other words, how it experiences its surroundings. An animal’s ability to perceive and respond to its environment includes specialized cells, neurotransmitters, and information processors both inside the brain and elsewhere in cells and organs. An animal’s umwelt is, by definition, limited to what mechanisms that particular species has evolved to interact with the space, objects, and activities around them. The profound differences between umwelts mean that no two animals – even, to some degree, animals within the same species – experience the same reality.
The human umwelt is largely determined by our sensory organs: eyes, ears, mouth, skin, and nose. Because we humans have long considered ourselves the pinnacle of evolution, we tend to look at other animals through anthropomorphic biases and language that screen our ability to imagine another animal’s perceptions. To help us overcome this bias, Yong introduces us to scientists around the world who spend their careers dissecting, probing, scanning, listening, and designing clever equipment and experiments to understand what it is like to fly like a bat, forage like a platypus, hunt like a spider or a mole, rumble like an elephant, or sense the time, sex, and direction of a visiting fox through a dog’s nose. We learn how fish and other aquatic organisms create and sense electrical fields for hunting prey or avoiding predators. How birds and moths migrate at night guided by magnetic fields. How bats and whales use echolocation, a sophisticated processing and computation system that creates a level of awareness that goes far beyond passive sensing.
What is remarkable about Yong’s writing is that he makes all this so relatable and compelling. He is a fabulous storyteller with great characters, both human and nonhuman, and a wry sense of humor. Yet he doesn’t spare the scientific details. Indeed, this book can be exhausting to read. An Immense World will push your brain to the limit and, like me, you may have to put it down for a few days to rest between chapters. Ed Yong makes you bring your A game, as a reader, as a human, and as just one of many animals.