The Front Sight As A Navigator Through The World

By Ida Dorsey

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.

Human eyes can detect color, depth and direction to a reasonable degree, but there are birds that can see in UV. There are also microorganisms that have eyes that do nothing but distinguish light from dark. The mantis shrimp has hyper-spectral vision and probably possesses the most complex color vision system among all animals.

The human eye works along the same principle as the camera or any other light-focusing device. Light enters the iris and is focused towards a small patch of photosensitive cells at the back, which convert the photons to neural signals. The iris can contract or expand to limit or increase the amount of light entering the eye.

Things are relatively simple before the light reaches the rods and cones (the light sensitive cells) but afterwards become appreciably more complex and as yet no convincing explanation of how people actually see has been put forward by the scientific community. The eye is a fascinating instrument and more still remains to be known about it. This is one reason why everyone must take every precaution to keep his or hers healthy, imagine losing such a wonderful gift!

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