A road map of the evolution of the eye

throughout HistoryMany organisms have evolved increasingly complex eyes in response to various pressures.

However, not all organisms experience the same pressures. That is why some creatures even today have very simple eyes or some have no eyes at all. These creatures exemplify eyes that are “frozen” in time. They provide snapshots or “snapshots” of how the eye has changed throughout its evolutionary journey.

Scientists study it Genes, Body part, and to know the road map of how the eye of vision of these creatures came. And so, we’ve put together a graphic timeline of the eye’s various stages of evolution using several candidate species.

Let’s look at how the eye has evolved over time.

Where does the vision come from?

of Retina It is a layer of nerve tissue, usually at the back of the eye, that is sensitive to light.

When light strikes, specialized photoreceptor cells convert light energy into electrical signals and send them to the brain. The brain then processes these electrical signals into images, creating vision.

The first visual appearance arose in unicellular organisms. They are the most common eyes in existence today, which consist of simple neurons that only distinguish light from dark.

The ability to recognize shapes, direction and color comes from the evolution of all the add-ons introduced to these cells.

Two main types of eyes

Two main types of eyes predominate in all species. Although they have different shapes or special parts, improved vision in both types of eyes is the result of small gradual changes that improve the physics of light.

Light eyes

Simple eyes are actually quite complex, but get their name because they consist of a single unit.

Some molluscs and all higher vertebrates such as birds, reptiles or humans have simple eyes.

Simple eyes evolved from colored cups and folded inward over time to take the shape we know today. Special structures such as the lens, cornea, and pupil arose to help improve the focus of light on the retina. This helps the brain process sharper and clearer images.

Mixed eyes

Compound eyes are made by repeating the same basic units of photoreceptors ommatidia. Each ommatidium is similar to a simple eye, lenses and photographers.

Clustered together, the ommatidia form a geodesic pattern commonly seen in insects and crustaceans.

Our understanding of the evolution of the compound eye is somewhat hazy, but we do know that rudimentary ommatidia evolved into larger, clustered structures to maximize light capture.

In an environment with no light, such as a cave, deep underground or the ocean floor, compound eyes are used to produce vision that gives them a slight advantage over other species.

How does vision improve?

Our dependence on technology and digital devices may be creating a new eye shape.

The muscles around the eye stretch to shift the lens when looking at something nearby. In response to this muscle tension, the round shape of the eye becomes elongated.

Screen time on mobile phones, tablets and computers has increased dramatically, especially during the Covid-19 pandemic. Recent studies are reporting an increase in childhood myopia, the inability to see far. Since the outbreak, cases have increased by 17%, affecting nearly 37% of school children.

Other evolutionary possibilities are currently less obvious to our eyes. It remains to be seen whether advanced corrective treatments such as corneal transplants or visual prostheses will have long-term evolutionary effects on the eye.

For now, colored contacts and wearable technology may be our vision of the future.