'An Immense World' dives deep into the umwelt of animals

Imagine taking a walk around your yard or park and hearing the sounds of insects.

The sound is created by the movements of insects called treehoppers that feed on plants. It isn't the same as the familiar vocalizations of crickets or cicadas; it's something different. Some sounds are similar to the sounds of machines. The noise from plants may be as loud as a busy street.

In An Immense World: How Animal Senses reveal the hidden realm around us, Pulitzer prize-winning science journalist Ed Yong explains that humans would not be able to hear the treehoppers' music without special equipment. Yong is able to hear the treehoppers in the wild and in the laboratory thanks to a device that converts the treehoppers' sounds into audible sounds. He is amazed by the sounds.

Yong writes in a perfect balance of scientific rigor and personal awe as he invites readers to grasp something of how other animals experience the world. Frog embryos hatch quickly if a snake shows up with a hard bite, but ignore rain, wind, footsteps and even the sound of rain, even if it's raining outside. Yong says that they have agency. They have an umbrella.

The term Umwelt refers to the perceptual world experienced by each animal, a highly specific kind of sensory bubble. When we walk our dog and she stops to smell every other bush or car tire, she's taking in through her nose smells that we don't normally take in. Humans and dogs have differing sensory bubbles.

Yong explores the Umwelten through chapters devoted to smells and tastes, light, color, pain, heat, contact and flow, sound, echoes and electric fields. The concluding two chapters discuss how senses work together and how a single species has disrupted senses through light and noise. Yong writes that our own Umwelt feels natural, but it's only one way to sense the world and it's only one way to understand it.

"It is all that we know, and so we easily mistake it for all there is to know. As a result, we tend "to frame animals' lives in terms of our senses rather than theirs."

To understand our own senses and to apply knowledge of animals' senses to produce new technologies are not motivators that Yong is indifferent to. I liked his perspective that animals aren't just stand-ins for humans. They have something in themselves.

Did you know that most insects can't hear? The visual fields of cows, who seem to show a fixed gaze to the point of being indifferent to the environment, wrap around in space so that cows can see in front, to the side, and behind them all at the same time? The only sense that exists without an associated organ is the sense that green sea turtles use to return to their nest on a small island after traveling 1,200 miles away?

Some animal sensory capacities are unavailable to us, while the sense of magnetism is rarely used by humans. Electric fish can work out the position, size, shape, and distance of objects by creating electric images from their skin. The Dolphins listen for echoes of their clicks.

"If a dolphin echolocates on you, it will perceive your lungs and your skeleton. It can likely sense shrapnel in war veterans and fetuses in pregnant women. It can almost certainly tell different [fish] species apart based on the shape of [their] air bladders."

It's not to say that humans can't echolocate. Daniel had both of his eyes removed due to cancer. He emits clicks that allow him to sense the location and shape of everything from houses and cars to trees. Even the best humans can't do what dolphins can do.

I am very fond of the book. I wonder about one choice Yong makes, exemplified in some examples above and in sentences like this one: "A dolphin is an echolocator that clicks with its nose and listens with its jaw." The word "it" is more suited to an object than a living being. "Dolphins are echolocators who click with their noses and listen with their jaws," seems to me more in line with Yong's view of animals as valuable beings. "If a cat or dog shares your home, I'll venture a guess that you don't refer to the four-footed family member who licks your face, naps in your lap, and sleeps on your bed as 'it'." I was one of the people who signed the letter asking for the media to use more respectful pronouns.

With our insistence on bright lights that disrupt dark skies, and a way of life that produces constant noise, we are seriously harming other animals' senses. There's hope because "sensory pollution is an ecological gimme", which means that conditions improve immediately when lights or engines are shut off. We can protect the Umwelten by extinguishing lights and using sound barriers.

I have relied on Yong's reporting at The Atlantic as he cracked open the fast-changing world of Pandemic Science in the course of COVID-19. Yong has brought into focus a host of other animal sensory worlds that co-exist with ours, and how we may protect them. He has presented a lot of scientific information to make it look easy. It's not easy at all. It's a great accomplishment.

Barbara J. King is a biological anthropologist. She wrote Animals' Best Friends: Putting Compassion to Work for Animals in Captivity You can find her on the social media site.