Scientists Edge Us Closer to Seeing What Other Animals See

Ever wonder how other animals literally see the world? Well, a new study brings us one step closer, and shows remarkable differences in perception.

Hiya!

I’d always heard people talk about how cool cat eyes are. I figured it was because of their pupil shape and because cats can see well in the dark. Then, I became a proud cat mom for the first time and noticed another fascinating aspect of cat eyes. Our human pupils and irises are at the front of our eyeballs, but a cat’s is set back behind a thick transparent layer. So, being me, I became curious about how the anatomy of their eye affects their vision.

I learned a lot and found this visual helpful, but what about other animals? How do insects, squirrels, or zebras see the world? It turns out that science just took a big step forward in finding out. For the first time, biologists developed a way to create videos depicting how other animals see the world visually. I’m obviously excited about this breakthrough because it helps me satisfy personal curiosities, but it’s also exciting for other reasons.

Human Perspective

Humans, like all other primates, are highly visual creatures. We rely heavily on visual cues to survive and have evolved eyes designed to detect a specific range of electromagnetic radiation wavelengths between 380 and 700 nanometers, which we call the visible light spectrum.

With the help of our tears, this light passes through a transparent, domed-shaped layer called the cornea, which bends light to help the eye focus. Some of this bent light enters the eye through the pupils, while the iris, the colored part of the eye, controls the amount of light entering the pupil by contracting and dilating it.

Once light enters the pupil, it passes through a clear lens, which works together with the cornea to focus it correctly on a light-sensitive layer of tissue called our retina. You can think of the pupils, iris, lens, and cornea as parts of a camera, while the retina would be the film.

The retina contains special cells called photoreceptors, which turn light into electrical signals that travel through the optic nerve to the brain. The brain then takes those signals and turns them into images we see.

It’s the photoreceptors that are of interest today. See, two types of photoreceptors are involved with our sight — rods and cones. Each of our eyes has over 100 million rod cells, which work best in darker conditions and are activated by only a few light particles. However, rods aren’t great at discerning color, which is why everything at night appears on a grey scale.

On the other hand, cones require more light to activate, which allows us to see colors. Most people have about 6 million cones per eye, split into three types: red, blue, and green. The overlap of the cones and how the brain processes the signals sent from them allows us to see millions of colors.

Some people have four cones, called tetrachromacy, which allows them to see even more colors. Intriguingly, research shows tetrachromacy is significantly more common in women, with some studies suggesting about 12 percent of women may have it.

Side note fun fact: On the flip side, men are more likely to be color-blind. Research even found that about 8 percent of caucasian males are born with a color vision deficiency compared to only 0.5 percent of females of all ethnicities.

Anyway, as impressive as our human eyes are, they’re only one of many evolutionary eye designs throughout the animal kingdom. Thanks to brilliant minds and advanced technology, scientists are learning how other animals perceive the world visually.

Beyond the Visual Light Spectrum