Without their eyes, most people would be completely lost, they are a means of navigating the world visually and are vitally important for all living organisms. Seeing is essentially, and the eyes have evolved some clever front sight formation methods in order to give humans the best picture of their world. Without this helpful organ, people would truly be in the dark ages.
Eyes are believed by scientists to have evolved at about the same time as the first animals (during the Cambrian explosion) in one species and within a few million years had spread to most of the others. No other sense organ is more common among the animals, probably a measure of the eye's utility. With the eyes usefulness also comes it's vulnerability due to it being constructed of mostly soft tissue.
Eyes in all animals differ in the way they are protected. In humans, this protection is threefold: firstly, the eyelids protect and water the eye. Secondly, the soft eyeball is situated in a resistant shell made of bone. Thirdly, a membrane surrounds it to protect it from outside influences. It is only natural that the human body has evolved to preserve the eye as much as possible. Therefore, people should also take extra care of their eyes so as not to lose the wonderful possibilities of eyesight.
Scientists have not thus far managed to build a device that will be able to replace the eye, regardless of how simple the process of seeing may seem when looked at first. The initial stages of seeing are, in fact simple, and consist of light detection, but the sophisticated interactions between the eye and the brain follow after, and researchers do not yet understand how these work.
An astounding fact about this amazing organ is that, amongst all animals, there is an incredible amount of types of eyes. In fact, there are 10 individual kinds of eyes, believed to have evolved separately from one another. In connection with the previously mentioned utility of sight, the fact that multiple organisms evolved eyes independently confirms the evolutionary importance of eyesight.
The type of sight animals and organisms possess is suited to their evolutionary needs. While some microorganisms possess eyes powerful enough only to distinguish between light and dark, some birds are even capable of seeing UV. Humans, for instance, have a moderately good ability to detect depth, color and direction, while the mantis shrimp's hyper-spectral vision is believed to be the most intricate system of color vision there is.
The human eye can easily be compared to a telescope, camera, microscope or other devices that use light focusing. Light first enters the iris, and is immediately focused onto a small patch of light-sensitive cells at the back. The cells transform the photons into neural signals. In order the change the quantity of light entering the eye, the iris changes size.
The previously described phenomenon is just one part of eyesight. While that one is relatively simple, it is what follows that baffles scientists till this day and yet has no explanation. How is it that the eye communicates with the brain in order to create an image from light-focused photons? Even if there is still no clear answer to this, one thing is well known: a world without sight would be a world without light, and to preserve the gift of eyesight, one must take extensive care of their eyes.
Eyes are believed by scientists to have evolved at about the same time as the first animals (during the Cambrian explosion) in one species and within a few million years had spread to most of the others. No other sense organ is more common among the animals, probably a measure of the eye's utility. With the eyes usefulness also comes it's vulnerability due to it being constructed of mostly soft tissue.
Eyes in all animals differ in the way they are protected. In humans, this protection is threefold: firstly, the eyelids protect and water the eye. Secondly, the soft eyeball is situated in a resistant shell made of bone. Thirdly, a membrane surrounds it to protect it from outside influences. It is only natural that the human body has evolved to preserve the eye as much as possible. Therefore, people should also take extra care of their eyes so as not to lose the wonderful possibilities of eyesight.
Scientists have not thus far managed to build a device that will be able to replace the eye, regardless of how simple the process of seeing may seem when looked at first. The initial stages of seeing are, in fact simple, and consist of light detection, but the sophisticated interactions between the eye and the brain follow after, and researchers do not yet understand how these work.
An astounding fact about this amazing organ is that, amongst all animals, there is an incredible amount of types of eyes. In fact, there are 10 individual kinds of eyes, believed to have evolved separately from one another. In connection with the previously mentioned utility of sight, the fact that multiple organisms evolved eyes independently confirms the evolutionary importance of eyesight.
The type of sight animals and organisms possess is suited to their evolutionary needs. While some microorganisms possess eyes powerful enough only to distinguish between light and dark, some birds are even capable of seeing UV. Humans, for instance, have a moderately good ability to detect depth, color and direction, while the mantis shrimp's hyper-spectral vision is believed to be the most intricate system of color vision there is.
The human eye can easily be compared to a telescope, camera, microscope or other devices that use light focusing. Light first enters the iris, and is immediately focused onto a small patch of light-sensitive cells at the back. The cells transform the photons into neural signals. In order the change the quantity of light entering the eye, the iris changes size.
The previously described phenomenon is just one part of eyesight. While that one is relatively simple, it is what follows that baffles scientists till this day and yet has no explanation. How is it that the eye communicates with the brain in order to create an image from light-focused photons? Even if there is still no clear answer to this, one thing is well known: a world without sight would be a world without light, and to preserve the gift of eyesight, one must take extensive care of their eyes.
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