As noted in the Encyclopedia Britannica, ethologists have adopted the word Umwelt, a German word for environment, to denote an organism’s unique sensory world.
There is plenty to ponder in terms of how my visual space world or visual umwelt compares to yours, but this type of reflection becomes even more expansive when we consider how our visual world compares to other sentient beings (think of Jerome Lettvin’s seminal paper in the late 1950s on What the Frog’s Eye Tells the Frog’s Brain). This is the challenge presented by a marvelous new book by Pullitzer Prize-winning science writer Ed Yong titled An Immense World: How Animal Senses Reveal The Hidden Realms Around Us.
The senses, as Yong notes, transform the coursing chaos of the world into perceptions and experiences – things we react to and act upon. They allow biology to tame physics. They turn stimuli into information. They pull relevance from randomness, and weave meaning into miscellany. However, Yong adds, an Umwelt cannot expand indefinitely. Senses always come at a cost. Animals have to keep the neurons of their sensory systems in a perpetual state of readiness so that they can fire when necessary. This is tiring work. He states: “Even when your eyelids are closed, your visual system in a monumental drain on your reserves.” Wow. Ponder that for a moment. Shades of Debbie Zelinsky’s Z-bell test and Amy Thomas’s finger snap localization. Well beyond my pay grade, that’s for sure.
In thinking about other animals, Yong comments, we are biased by own senses and by vision in particular. Our language is ripe with visual metaphors, but language can be both a blessing and a curse. It gives us the tools for describing the Umwelt of another being, even as it insinuates our own sensory world into those descriptions. Chances are you’ve heard of Occam’s Razor, otherwise known as the Law of Parsimony, or accepting simpler explanations over more elaborate ones. Yong cites the Zoologist Donald Griffin who laments that biologists are too often swayed by “simplicity filters”.
Occam’s razor is a principle that is only true when you have all the necessary information at hand. A scientist’s explanation (and to that we might extend a physician’s diagnosis) is dictated by the data she collects, which are in turn influenced by the questions that she asks, which are steered by her imagination, which is delimited by her senses. This leads to a powerful observation that the boundaries of the human Umwelt often make the Umwelten of others opaque to us.
If one had to encapsulate Yong’s observations on the Umwelt, this extended quote might do it:
“Earth teems with sights and textures, sounds and vibrations, smells and tastes, electric and magnetic fields. But every animal can only tap into a small fraction of reality’s fullness. Each is enclosed within its own unique sensor bubble, perceiving but a tiny sliver of an immense world. There is a wonderful word for this sensory bubble – Umwelt. It was defined and popularized by the Baltic-German zoologist Jakob von Uexküll in 1909. Umwlet comes from the German word for ‘environment’, but Uexküll didn’t use it simply to refer to an animal’s surroundings. Instead, an Umwelt is specifically the part of those surroundings that an animal can sense and experience – its perceptual world … The majesty of nature is not restricted to canyons and mountains. It can be found in the wilds of perception – the sensory spaces that lie outside our Umwelt and within those of other animals.”
But would that extended quote do the subject justice? Not really, and Yong hints at that in Chapter 2 titled Endless Ways of Seeing. It is a sumptuous read, its centerpiece being an overview of the smorgasbord of eyes in this world. And this smorgasbord, as he demonstrates, brings with it a dizzying yet delightful medley of visual Umwelten.