what i'm reading: an immense world by ed yong

Long ago, I briefly observed one of our dogs do something that has always stayed with me. 

I was walking Cody in our New York City neighbourhood, and saw, in the distance, a neighbour walking a dog that Cody was in love with, called Little Bear. Cody had never interacted with Little Bear beyond passing, with both dogs on-leash, but nevertheless, Cody was smitten. When she saw Little Bear, our mild-mannered lab-shepherd mix became almost uncontrollable -- barking, whining, pulling, and generally freaking out.*

On this particular walk, I didn't have a lot of time, and needed to make it brief. Cody was unaware of the presence of Little Bear in the distance, so I slowed down, waiting until the dog and its person had turned a corner and were headed away from us.

Some minutes later, Cody and I approached where Little Bear had been. Cody sniffed the base of a tree. Her head shot up, and she frantically looked all around, her eyes wild and expectant, whining the way she only did for Little Bear, then pulled in the direction I had seen Little Bear go. From that one sniff, Cody knew not just that a dog had been there, but what individual dog had been there and in what direction they had gone.

I thought of this while reading An Immense World: How Animal Senses Reveal the Hidden Realms Around Us. In An Immense World, Ed Yong, a science writer at The Atlantic, takes the reader on a tour of animals' Umwelten. Umwelt, Yong tells us, is a term for the "sensory bubble" in which an animal lives. It is the world the animal perceives. That sensory bubble is perfectly adapted to the animal and what it needs from its environment, and utterly different from our own.

Umwelt: the world according to dogs. Or whales. Or rats. Or spiders.

Dolphins, dogs, hundreds of different species of insects and spiders, different species of birds -- and so on and so on -- each have their own Umwelt. These sensory bubbles are best understood by removing humans from the picture completely. It's not that the dog has better hearing or a better sense of smell than humans. They do -- but that's not what's most interesting, and not what Yong wants to show us. It's what smell and hearing do for dogs. It's the world according to dogs (spiders, rats, whales, crocodiles, elephants, etc.).

An Immense World includes so many eye-popping stories and facts -- all examples of its subtitle -- that choosing a few for a review may be the most daunting writing challenge I face this year. 

Alligators and crocodiles are covered -- head to tail -- in sensors that detect vibrations in the surface of the water. These pressure detectors are 10 times more sensitive to pressure fluctuations than human fingertips. Even with its eyes covered and its ears plugged, when a drop of water hits the surface of its tank, an alligator test subject lunges and snaps where it lands.

A spider's web is a "vibrational landscape" -- made from the spider's own body -- that tells the spider what and where its next meal will be. What's truly astonishing is that the spider can adjust its web "as if tuning a musical instrument", altering the speed and strength of the web's vibrations by changing the stiffness of the silk, the tension in the strands, and the shape of the web, depending on the type of prey that's available. And some spiders can camoflage their footsteps to encroach on another spider's web and steal their prey without being detected. 

Owls, renowned for their huge eyes and raptor-sharp eyesight, actually hunt by hearing. The disc of stiff feathers on an owl's face funnels sounds towards its ears -- which sit asymmetrically on the owl's head, enabling it to pinpoint the location of prey in both vertical and horizontal planes, as if on a radar screen. 

Many insects have ears on their legs; many butterflies hear with their wings. Rattlesnakes hear with their tongues.

Dogs can detect (by smell) a single fingerprint on a microscope slide that has been left outside, exposed to elements, for a week.  

A seal's whiskers detect vibrations in the water, and can discriminate among shapes and textures. Swimming fish leave a trail of moving water -- a "hydrodynamic wake" -- not visible to human eyes.  A harbor seal can follow a herring from almost 200 yards away. Even blindfolded and with their ears plugged, seals can follow the hydrodynamic trail of their dinner.

Rodents call to each other in frequencies too high to be audible to humans. 

Pups [of rats] that are separated from their nests make ultrasonic "isolation calls" that summon their mothers. Rats that are tickled by humans make ultrasonic chirps that have been compared to laughter. Richardson's ground squirrels produce ultrasonic alarm calls when they detect a predator . . . Male mice that sniff female hormones produce ultrasonic songs that are remarkably similar to those of birds, complete with distinctive syllables and phrases. 

The section on bird calls and whale sounds is absolutely mindblowing. If I tried to summarize it, I'd end up copying whole pages from the book. Trust me: the sonic Umwelt of birds and whales is not at all what you might think.  

Allan has more examples in his review here. He chose An Immense World as the best book he read in 2023.

An immense world, and a small language

Dogs perceive the world primarily through smell and hearing. What smell means to a dog -- the information dogs receive from smell, what they can know through smell, how they need it and use it -- is so different than our own sense of smell, that they shouldn't even be called the same thing. 

The animal sense that is perhaps most difficult to comprehend is the one that most humans rely on most heavily: vision. We imagine we are seeing the world as it is. In fact we are seeing the world as it is for humans. Rattlesnakes see infrared radiation. Birds can see ultraviolet light. Some animals see in almost total darkness. Others see fantastically long distances -- but only if they look downward.

One of the many insights this book has brought me is the paucity of the English language when it comes to describing sensory perceptions. 

We are taught that humans have five senses -- but more than that, we are taught that there are five senses. We speak of "a sixth sense" or "extrasensory perception," as something freakish or otherworldly. An Immense World has taught me that there are at least six or seven general senses, and within those broad categories, perception is wildly varied. 

An elephant, a peacock, an iguana, and a spider are all animals -- but that broad category tells us very little, and bears no hint of how completely different those four animals are. Likewise, the words touch, taste, hearing, sight, and smell mean completely different things within the Umwelten of different species.

It's great, don't be afraid

Yong's writing is so engaging and captivating, and sprinkled with gentle humour. The book is framed as a journey of discovery: the author connects with scientists who study the sensory perception of a huge array of animals. He is continually fascinated by what he finds -- and the reader comes along for the ride. This infuses An Immense World with a warmth and generous joy of discovery. 

The science of perception -- what produces vision or hearing -- is somewhat beyond me, but that's a few paragraphs sprinkled here and there, not the majority of the book.

I was hesitant to read this book because of the terrible sadness that underlies so many animal stories -- habitat destruction, pollution, slaughter for human greed, rampant cruelty and abuse. Cruelty to animals is the one place I cannot go, the thing I cannot read about or watch. Allan assured me that An Immense World was not that book. There are sentences here and there that are sad (and stay with me) but overall, it is a celebration of the wonders of animals. As Yong says, the book is about "animals as animals," an attempt to understand how animals perceive their own worlds -- to enter their Umwelt. 

I am actually still reading An Immense World. Every so often, I think, this is very detailed, perhaps I'll just skim this bit. Then I skim maybe one paragraph, and realize I'm missing yet another incredible example, or some gem from one of the many humourous footnotes, and I return to my close read. This book is just too good to miss any page.

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* Many years later, Tala displayed this same smitten behaviour, even more vehemently, towards a beautiful Collie we referred to as The Boyfriend. Becoming aware of The Boyfriend from any distance, Tala would whine and cry and drag me over to him. She would put her face against his cheek, and close her eyes, in apparent rapture. The Boyfriend, as is often the case with dog romance, was indifferent to Tala. The Boyfriend's people, sadly, weren't amenable to any interaction. To avoid breaking Tala's heart every day, when I spotted The Boyfriend, I would quickly make a U-turn to avoid them. From a great distance, Tala would sniff the air, stare into the distance, and quietly whine.