An Immense World

The question

Ed Yong is a British-born science journalist who wrote for The Atlantic, where his coverage of the COVID-19 pandemic won the Pulitzer Prize for Explanatory Reporting in 2021. His first book, I Contain Multitudes (2016), was about the microbes that live in and on animals. An Immense World, published in 2022, turns to the senses.

Its question is what other animals perceive. A dog, a bat, a bee and a human standing in the same room live, in effect, in different worlds, because their senses pick up different parts of reality. Yong takes the concept of the Umwelt from the Baltic German biologist Jakob von Uexküll, who introduced it in 1909: the part of the environment that an animal can sense and experience. Every animal’s Umwelt is limited. The question is what lies within each one, and what that tells us about the limits of our own.

The path through it

Yong structures the book by sense, a chapter each, moving from the familiar to the strange.

Smell and taste. Dogs live in a world of odour, detecting traces that are years old; their noses have far more scent receptors than ours, and their sniffing separates air for breathing from air for smelling. Ants communicate through chemical trails. Yong describes how strongly a world of smell differs from a world of sight: smells linger and spread, revealing the past.

Light and colour. Eyes have evolved many times, and they serve different purposes. Scallops have dozens of eyes; some animals see ultraviolet, or polarised light, which humans cannot. Colour, Yong emphasises, is not a property of objects but a creation of the brain, and different animals create different colours. A bee or a bird sees flowers in patterns invisible to us.

Pain, heat and touch. He describes animals that sense the warmth of their prey, such as pit vipers, and the fine touch of a sea otter’s paws or a star-nosed mole’s snout, one of the most sensitive touch organs known.

Vibration and sound. Many animals communicate through vibrations in the ground or in plants, a hidden channel that researchers have only recently begun to hear. Birds hear their songs with far finer timing than humans can.

Echoes. Bats and toothed whales build images of their surroundings from the echoes of their calls, a sense so foreign to us that the philosopher Thomas Nagel used it in his famous 1974 essay asking what it is like to be a bat.

Electric and magnetic fields. Some fish generate and sense electric fields, using them to navigate and communicate in murky water. Many animals, including migrating birds and sea turtles, sense the Earth’s magnetic field, though how they do so is still not fully understood.

Finally, Yong turns to how the senses are integrated in a single animal, and then to the effects of human activity.

Where it arrives

The book arrives at two conclusions. The first is about humility. Our own Umwelt feels like the whole of reality, but it is one narrow window among many. Trying to imagine another animal’s perception, while accepting that we can never fully enter it, enlarges our sense of what the world contains.

The second is about responsibility. The final chapter describes sensory pollution: artificial light that disorients migrating birds and hatching turtles, underwater noise from ships that drowns out whales’ communication, and other forms of human disruption. Yong argues that we are filling the world with stimuli that other animals did not evolve to handle, and that we can reduce this damage if we pay attention, for example by dimming lights during migrations.

What remains open

The book leaves open what other animals experience, as opposed to what they detect. Yong is careful to distinguish sensing from consciousness, and he does not claim to know what it feels like to be a bat or a bee. That question, Nagel’s question, remains one of the deepest in philosophy of mind.

It also leaves open many scientific questions, such as how magnetic sensing works, and how much of what animals perceive scientists have simply never thought to look for.

What it asks of someone deciding

The book asks what lies outside your Umwelt. Every person, team and organisation perceives only part of its environment, shaped by its tools, measures and habits. The site’s idea page Silent Evidence explores what is missed when we look only at what is visible.

It asks how others perceive the same situation. Customers, colleagues and competitors may be sensing things you cannot, through different experiences and priorities. Yong’s method, trying to imagine another’s perception while admitting you cannot fully share it, is a discipline of empathy.

And it asks what your activity is doing to others’ worlds. Products and organisations create side effects that their makers cannot sense but others experience intensely. Paying attention to them is the first step to reducing them.