In a captivating opening keynote at the 2024 Annual Meeting of the Association for Research in Vision and Ophthalmology (ARVO), Pulitzer Prize-winning author and renowned science journalist Ed Yong led attendees on an exploration of the fascinating world of animal perception. Through his insights and experiences, Mr. Yong’s presentation illuminated the diverse ways creatures perceive their surroundings, challenging conventional notions of sight and sensory experiences.
A cocktail of senses
Mr. Yong kicked off his address with an endearing introduction to his corgi, Typo. Exploring the complexities of canine olfaction, he delved into the intricate design of a dog’s nasal structure, highlighting how side slits facilitate continuous scent detection.
“Those side slits create these rotating vortices of air that sweep in scented molecules into the dog’s nose even when it is breathing out,” he explained.
Such adaptations underscore the remarkable sensory capabilities of dogs and their unique way of experiencing and navigating the world through scent.
“When Typo encounters something new, he sniffs it. He sniffs everything,” Mr. Yong recalled. “He trundles along quite happily, only to grind to a halt and furiously investigate some patch of pavement or sidewalk that looks completely nondescript to my eyes but is clearly bursting with interest and information to his nose.”
Mr. Yong then introduced the concept of “umwelt,” a German term describing the sensory environment experienced by individual organisms.
“Umwelt is a cocktail of space,” Mr. Yong explained. “It’s the sights and sounds and textures and smells that I perceive. And it’s going to be very different than what my dog can perceive, or what a bat or an elephant or a whale or a bird or any other animal might be able to sense. We are each only getting a thin fraction of all there is to perceive.”
Seeing beyond sight
Mr. Yong drew from nature’s abundance to showcase awe-inspiring examples of animal perception, such as the echolocation abilities of bats and the rattlesnake’s prey detection through infrared sensing.
“A rattlesnake, sitting on the top of my head, will be able to strike a mouse sitting at the end of my finger, with perfect accuracy because of its heat detection sense,” Mr. Yong elucidated.
Mr. Yong emphasized the diversity of sensory experiences found across the animal kingdom, challenging attendees to rethink conventional notions of vision and perception, and urging a deeper appreciation for the myriad ways creatures interact with their environments.
“My argument is that what animals perceive, their umwelt, is worth thinking about,” he asserted. “Not simply because, in some cases, their abilities exceed our own, but simply because they are different.”
Seeing is smelling
Highlighting the pivotal role of opsins in vision, Mr. Yong remarked, “Despite all this variety, all animal eyes are unified in one particular respect. They all depend on a single group of proteins called opsins.”
Yong further explained the mechanics of vision, detailing how opsins interact with chromophores to initiate the chain of chemical reactions leading to visual signal transmission. Comparing this process to a car’s ignition, he vividly illustrated the molecular intricacies involved when light stimulates the eye’s photoreceptor cells.
“The chromophore is a car key, and the opsin is an ignition switch,” said Mr. Yong. “The two fit together. The light turns the key, and the engine of vision whirls to life.”
Explaining that opsins are specialized variants of GPCRs (G protein-coupled receptors) with a unique light-sensitive partner, Yong proposed that vision fundamentally resembles smelling—an elegant convergence of seemingly distinct sensory modalities.
“GPCRs sit on the surface of cells and they bind to molecules that float past, which they recognize by their shape. This is the basis of smell,” Mr. Yong said. “Opsins are special variants of GPCRs for two reasons. First, they have a partner, the chromophore, that is sensitive to light. And second, they don’t let that partner go. Most GPCRs recognize a chemical and then release it. The opsins hold onto the chromophore.”
“I think this is really cool because it means that vision is just smelling, right?,” added Mr. Yong.
Extraordinary eyes
Drawing on captivating examples from the animal kingdom, Mr. Yong showcased diverse ocular adaptations and their profound influence on visual perception, from the jumping spiders’ moon-gazing abilities to the lightning-fast reflexes of killer flies.
“Killer flies can capture their prey in about a quarter of a second, which is the time it takes for you to blink,” Mr. Yong shared.
Delving deeper, Yong explained that eyes can do one of two things. “They can either have very high resolution or they can have very high sensitivity,” he said. “They cannot do both at the same time. While humans have better resolution, other animals have better sensitivity.
As much as humans try, there exist inherent limitations to comprehending the sensory experiences of other creatures. Yong emphasized the insurmountable chasm that separates human perception from that of other animals, challenging the audience to contemplate the unknowable depths of sensory perception.
“Science can take us close to its edge. Technology can push us a little bit further over. Good writing, maybe, can help us to imagine how we might cross it,” Yong remarked.
Sensory disruption
Mr. Yong concluded his address by highlighting the profound impact of human activities on the natural world, lamenting the encroaching threat of sensory pollution on ecosystems and biodiversity.
“We think light is synonymous with beauty, goodness, and knowledge, but it can be a pollutant,” he said. “It can waylay migrating birds from their already arduous journeys. It can distract pollinating insects from the plants they’re meant to service. It can cause a huge amount of harm to the animals around us.”
From the pervasive glow of artificial light pollution to the disconnection from the natural world, Mr. Yong urged the audience to confront the consequences of sensory disruption and reclaim their connection to the wilderness.
“I think of sensory pollution as the pollution of disconnection, severing our relationship with the natural world,” he surmised. “When we do that, we push nature away from us.”
“Our ability to think about the umbilicals of other animals, I think, gives us an antidote to that. A way out of our perception of nature is not being part of our lives,” Mr. Yong asserted, invoking a call to action to rekindle our reverence for the intricate web of life that surrounds us.
Editor’s Note: The Annual Meeting of the Association for Research in Vision and Ophthalmology (ARVO 2024) is being held from 5-9 May in Seattle, Washington, USA. Reporting for this story took place during the event.
