People love to think about aliens, about what they might look like and how we could communicate with them. But we don't need to look that far, writes British-American science journalist Ed Yong in his fascinating new book, “An Immense World: How Animal Senses Reveal the Hidden Realms Around Us”.
Our world is colourful, often noisy and hectic, it can overwhelm us. And yet: everything we see, smell and hear is only a small part of what we could perceive if we had the necessary sense organs.
We are surrounded by sounds that are too high or too low for our ears, ultraviolet and infrared light and smells that can be perceived by a dog but not by a human nose. There are also surface vibrations, for example, which we don't notice but which are used by 200,000 species of insects to communicate.
“The world around us is full of signals that we don't notice,” Yong says. He goes through the senses of living creatures one by one - smelling and tasting, seeing, hearing, sensing pain, temperature and vibration, and the senses of magnetic and electric fields that are so foreign to us - and explains the nature of the organs that underlie them.
“We all live in the same world, but it looks very different to different beings”
To do this, he visited researchers in their laboratories and in nature, looked through glasses with colour filters and listened with highly sensitive microphones to how humpbacked chirps, a type of cicada, produce vibrations that are transmitted to others via the leaves on which they sit.
He has had assassin flies shown to him that taste with their feet instead of their tongues and that see so fast that everything we do must seem like slow motion to them.
In fish, Yong reports, the taste receptors are distributed over the entire body. Wherever there are no scales, a fish can taste; it is a kind of swimming tongue.
Yong tells of deep-sea creatures that are so sensitive to light that they go blind when curious researchers shine the headlights of their submarines on them, of ice worms that can cope with arctic cold but die when a human takes them in his warm hand, and of fire beetles that prefer to mate in a burning forest: These find the fire with the help of spherical infrared sensors that sit behind their middle legs.
Just as amazing as the diversity of animal senses is the resourcefulness of the researchers who are on their trail. For example, they tied scallops to small seats in front of a monitor and showed them films to determine what they can see with their up to 200 eyes.
Or they brushed ants with the smell of their dead comrades, which led to them being shipped to the ant graveyard by their roommates, whether they wriggled or not. This proved that ants orientate themselves primarily by smells.
We all live in the same world, but it looks very different to different beings, Yong explains. The biologist Jakob von Uexküll called what a being can perceive its environment. Just as there are windows in a house with different views, animals have different senses, each offering a different picture of the world.
“It is a common misunderstanding, says Yong, to assume what we perceive is everything that can be perceived”
We cannot imagine how animals perceive each other, nor what the world looks like to them, he said. For example, flowers glow in ultraviolet colours for some bird species and insects that we do not see.
In addition, flowers are surrounded by characteristic electric fields. We do not perceive these either, unlike bees and bumblebees, for example, which register them through their many tiny hairs.
The world suddenly seems strangely alien. It is a common misunderstanding, says Yong, to assume what we perceive is everything that can be perceived. And to act accordingly.
In the last chapter, for example, he pleads that when intervening in the environment, we should also think of those who feel differently than we do: insects deprived of their orientation by light, birds and turtles, fish stressed by noise under water. And also of ourselves: We are far too quick to accept a world in which many ways of perception are no longer possible, such as the view of the Milky Way disappearing in the brightly lit night sky.
Yong writes that he is neither interested in records nor in better or worse when observing the senses of animals; he is only interested in the diversity and the possibility of better understanding living beings. For we are the only ones who can realise that others see the world differently. Only we can find out what diversity there is out there.
A fascinating, if perhaps overly-long work that assigns humans their place: as one among many who live in worlds we can hardly imagine. This book expands our world - far more than any alien fantasy.
An Immense World: How Animal Senses Reveal the Hidden Realms Around Us. By Ed Yong.