Our most loved pets, like cats and dogs, have exceptional vision. In some aspects of vision, our pets have superior vision to us. For example, cats and dogs can see better in the dark and are more sensitive to perceiving motion, which makes them good hunters.
However, humans have a skill that is only found in primates: the ability to see in detail. Our vision is the result of millions of years of evolution. Our eyes have come a long way since the beginning of their evolving journey. We began with nothing more than a light spot able to detect light and dark.
Now, we are able to go from reading a book to looking 20 feet in the distance with our eyes taking less than a second to adjust. What we see is vibrant colors and every detail imaginable. Details that painters spend their whole lives trying to capture, our eyes pick up on every day.
Human eyes are the original high definition.
What Sets Us Apart from Other Mammals
In looking to understand our own vision and how our eyes work, we’ve often relied on mice. Mice have similar eye structure to our own and can be easily studied to find cures for diseases such as cataracts and glaucoma.
For all our similarities, however, there is one part in the retina that humans have while mice do not. The fovea, a dimple found in the retina is what allows us to perceive such details. Mice do not have a fovea in their retina, meaning that they can’t see as we do.
Other animals like our dogs and cats are also missing this incredible feature in their eye structures. While our cats may see better at night and our dogs may be able to spot a squirrel faster than we can, they will never be able to see the details on a single leaf or snowflake.
Though this is all very poetic and romantic, our eyes see in such detail for more than just our viewing pleasure. Today we use our sharp vision to aid in activities such as reading and driving. But what did the first humans need it for?
Like any other type of evolution, our eyes evolved to help us survive. We developed depth perception to be able to better hunt prey and avoid dangers like cliffs. The ability to see in such detail is also a result of our instinct to survive. We developed sharp vision to see things that other animals would miss.
Animals can detect motion much better than we can, but what if the predator stalking you was still as a statue? Any other animal may not see it coming, but a human would be able to see that snake camouflaged against a rock. No matter how still the snake is, we’d be able to see the fine details of the snake’s scales, its black eyes and red tongue.
Humans would run. A poor mouse would be eaten.
The fovea is the one element that separates primate’s eyes from other mammals. However, studies have shown that small fovea-like dimples seem to be developing in certain types of reptiles, fish and birds. The foveae in their eyes have not evolved to work as ours do.
In some animals, the fovea is almost completely obsolete. Researchers can clearly see that a fovea is present, but the dimple is bogged down by other cells that there is heavy doubt that the fovea is functional. Maybe in another few thousand years we’ll have birds that don’t fly into windows anymore, no matter how clean they are!
In humans, the fovea is very present and very active every minute of the day. As you read this, your foveae are working to make sure you capture every detail of every letter and photograph.
The optic nerve is the messenger of the eye. It is responsible for sending information collected by the eye to the brain through nerve impulses. Half of the information that is sent by the optic nerve comes from our retina. This includes colors, shapes, and shades, light and dark.
The other half comes solely from the fovea. The fact that one little dimple in our retina is responsible for collecting half of our vision information is incredible. Even Charles Darwin, the father of evolution theory, was perplexed at how complex the eyes are, saying that the structure of the human eye was too advanced to have evolved on its own.
Of course, we now know that our eyes did evolve on their own, from that little light spot to the detail-seeing eyes we have now.
More Details, Lower Sensitivity
Our eyes are more focused on seeing the details because that’s how we’ve evolved. Animals don’t read, but humans have been reading since the dawn of humankind; even if writing back then was just cave drawings. Nevertheless, humans needed to have sharp vision to perceive these drawings.
If there’s one thing our fovea can’t perceive, it’s fast changing visual cues. For example, if you hit refresh on your computer’s browser, you wouldn’t notice a flicker in the screen. If you hadn’t hit refresh, you wouldn’t even know that isn’t the screen you were just looking at.
When you refresh a screen there is always a slight flicker of the webpage. Sometimes you’ll see it happen if the page flickers for longer than normal, but otherwise it is completely undetectable.
This is because our eyes have lower sensitivity to fast changes. A flip book with images works on the principal that our eyes don’t work fast enough to see the images as separate entities, but rather one long, continuous motion.
The human eye is capable of many things, but being able to perceive such detail is what sets us apart from other mammals.
Though we tend to use our sharp vision less for running from predators and more for leisurely activities such as reading, writing, drawing, painting and driving these days; one thing is for certain – our eyesight would be nothing without the fovea.