Life in a New Perspective: The Human Eye vs the Animal Eye
Written By: Eimaan Shahid
Imagine living life from the perspective of your pet. Does your cat know what you really look like? Is your dog purposely chewing all of your shoes, or can he not distinguish between his chew toy and your new joggers? When we peer into the fish tank at the dentist’s office, are the fish looking right back at us? Even the birds flying overhead on a sunny afternoon, what do they see us, humans, as? All of us see through the same perspectives our entire lives. Since birth, we all have had the same pair eyes that allow us to recognize different colors, see on a 190-degree horizontal field view, and examine every detail in our constantly changing surroundings. Our human eyes, although able to see a wide spectrum of colors, and shapes, are quite limited in capabilities in comparison to our furry counterparts.
Every night when the sun begins to set, humans turn on their lamps and house lights on so that we are able to see and navigate through the dark. Out in the wild, most animals do not need a light source to be able to see. This main difference of night vision between our human sight in comparison to how dogs or cats see begins with the structure of the eye. Both animals and humans have structures located at the back of the eye called the retina. The retina contains two types of light-sensitive cells, rods and cones. Rod cells are accountable for visions at low levels of light, and cone cells deal with seeing light at different wavelengths and colored vision (Rods and Cones, n.d). Each species has a different number of cone and rod cells in the retina depending on their survival needs and lifestyle. The human retina contains nearly 120 million rod cells and 6 million cone cells. Cats have a lot more rod cells than we do, which gives them the upper hand when it comes to seeing at night. However, human eyes are better at detecting color as we have about 10 times more cone cells that cats do! The same goes for dogs; dogs have more rod cells but fewer cone cells than humans. Dogs are also unique because they can only recognize two primary colors; blue and yellow. Meanwhile, humans and cats can recognize combinations of red blue and green (Buzhardt, 2019).
Figure 1.0 A landscape from the perspective of a human (top) and the perspective of a cat (bottom)
The formation of the retina is just one of the differences between human and animal eyes. With both eyes open, humans can see a field view of around 180 degrees horizontally and 150 degrees vertically (Mayzurk, 2020). In comparison to animals, the field of view for humans is not that impressive. As many people’s household pets, cats and dogs have a field view of around 200 degrees, giving them a stronger peripheral vision (Ghose, 2013). Chameleons, a color-changing species of lizards, have one of the widest ranges of vision; their protruding eyes allow them to see a full 360 degrees!
Although our human eyes are unable to see in the dark, one area where our eyes are superior in comparison to household pets is visual acuity. Visual acuity, more commonly known as the sharpness of vision, allows us to see very fine details. A study done by Eleanor Caves, a researcher at Duke University, collected visual acuity data from 600 different species. After eagles, owls, sheep, and goats, human eyes were ranked near the top of the list for sharpest eyesight (Smith, 2018).
Cats and dogs do have more enhanced eyesight than humans do in some aspects such as field of view and night vision. However, eagles are the kings of vision when it comes to the animal kingdom. On average, eagles see an average of 8 times farther than humans. This translates to seeing objects from about a 2-mile distance (“Eagle Vision” 2016)! The structure of an eagles eye is deeper than that of humans, which allows the eagle to see much sharper. A large number of cone cells in the retina also allows for eagles to see colors that are not on the spectrum the human eye can recognize, and they also see colors more vividly. Since eagles have angled eyes, their field of view is 340 degrees. The lens on an eagle eye also has the ability to change shape between far and near objects much more efficiently than humans. It’s safe to say that eagles have exceptional eyesight!
Although it would be fascinating to see life through the perspective of a dog, cat, eagle, or even a goldfish, our human eyes simply do not have the capabilities to do so. Even though we humans can’t see at night like our pets, very far like eagles, and can’t have a 360-degree view of our surroundings like chameleons, the human eye is still a fascinating creation that is able to see vivid colors and examine details all on a wide horizontal view.
Sources
Buzhardt, C. (2020). Do Cats See Color? Retrieved July 14, 2020, from https://vcahospitals.com/know-your-pet/do-cats-see-color
Human Vision Vs Eagle Vision. (2019, October 24). Retrieved July 14, 2020, from https://www.insightvisioncenter.com/human-vision-vs-eagle-vision/
Mazuryk, T., & Gervautz, M. (2018, August 01). Human Field of View. Retrieved July 14, 2020, from https://www.researchgate.net/figure/11-Human-field-of-view-a-vertical-b-horizontal-from-Heil92_fig10_2617390
Rods and Cones. (n.d.). Retrieved July 14, 2020, from https://www.cis.rit.edu/people/faculty/montag/vandplite/pages/chap_9/ch9p1.html
Smith, R. A. (2018, May 30). Details That Look Sharp to People May Be Blurry to Their Pets. Retrieved July 14, 2020, from https://today.duke.edu/2018/05/details-look-sharp-people-may-be-blurry-their-pets
