Friday, November 28, 2014

The Front Sight As A Navigator Through The World

Tags

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.

While evolution has led the human body to evolve different means of protection, these can be separated into three layers: the most outer layer is the skin eyelid that covers the eye and also waters it. The second layer is the membrane that surrounds the soft tissue of the eyeball. And the remaining layer is the cavity made of bone in which the eyeball resides. Such highly developed mechanisms are a clear indication that eyes should be well taken care of.

Explaining the basic working principle of the eye is simple, despite this, human beings are yet to create a device that even comes close to matching the eye's function. This is because the light is not simply a light detector, but does what it does through a complex interaction with the brain. In fact, it would take a powerful super computer to model the visual cortex on it's own.

In favor of the claim that the eye is one of the most important sense organs in all organisms is the fact that there are more than 10 distinctive kinds of eyes present among various animal species. On top of that, it is believed that these evolved independently from each other. The fact that it is not just a few organisms that recognized the evolutionary importance of eyes, but ten different once, underlines the claim that eyes are of such great importance.

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.

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.




About the Author:




EmoticonEmoticon