Human Eye

Human eye is a very complex structure. It can distinguish about 10 million colors. There are rod and cone cells in the retina which allow conscious light perception and vision including color differentiation and the perception of depth.

According to the evolution theory of Darwin, the living things evolved from simple to the  the complex through gradations. So evolution of the eye poses a challenge to the Darwin’s theory because eye consists of many parts intricately connected to each other. The critics argue how could something so complex, they argue, have developed through random mutations and natural selection, even over millions of years?

If evolution occurs through gradations, the critics say, how could it have created the separate parts of the eye — the lens, the retina, the pupil, and so forth — since none of these structures by themselves would make vision possible?

Darwin acknowledged from the start that the eye would be a difficult case for his new theory to explain. Difficult, but not impossible. Scientists have come up with scenarios through which the first eye-like structure, a light-sensitive pigmented spot on the skin, could have gone through changes and complexities to form the human eye, with its many parts and astounding abilities.

Through natural selection, different types of eyes have emerged in evolutionary history — and the human eye isn’t even the best one, from some standpoints. Because blood vessels run across the surface of the retina instead of beneath it, it’s easy for the vessels to proliferate or leak and impair vision. So, the evolution theorists say, the anti-evolution argument that life was created by an “intelligent designer” doesn’t hold water: If God or some other omnipotent force was responsible for the human eye, it was something of a botched design.

Biologists use the range of less complex light sensitive structures that exist in living species today to hypothesize the various evolutionary stages eyes may have gone through.

Here’s how some scientists think some eyes may have evolved: The simple light-sensitive spot on the skin of some ancestral creature gave it some tiny survival advantage, perhaps allowing it to evade a predator. Random changes then created a depression in the light-sensitive patch, a deepening pit that made “vision” a little sharper. At the same time, the pit’s opening gradually narrowed, so light entered through a small aperture, like a pinhole camera.

Every change had to confer a survival advantage, no matter how slight. Eventually, the light-sensitive spot evolved into a retina, the layer of cells and pigment at the back of the human eye. Over time a lens formed at the front of the eye. It could have arisen as a double-layered transparent tissue containing increasing amounts of liquid that gave it the convex curvature of the human eye.

In fact, eyes corresponding to every stage in this sequence have been found in existing living species. The existence of this range of less complex light-sensitive structures supports scientists’ hypotheses about how complex eyes like ours could evolve. The first animals with anything resembling an eye lived about 550 million years ago. And, according to one scientist’s calculations, only 364,000 years would have been needed for a camera-like eye to evolve from a light-sensitive patch.

Dehradun in Mythology

In the earliest legend, Dehradun was a part of Kedarkhand, the abode of Great God Shiva whose popularity in this region is reflected in the hills being called after Him as Shiwalik.  The place also figures in two mythological epics Mahabharata & Ramayana. It is said that Rama and his brother Lakshmana came here to do the penance after the death of Ravana at their hands. Five Pandava brothers also sojourned here while on their way to inner recesses of Himalayas.

Another legend is connected with a little river called Suswa. After Indra made fun of 60000 pygmy brahmins for trying vainly to cross the vast lake formed by the footprint of cow filled with water. They prayed here by doing penance and mortification to create an alternate Indra who will be superior to the existing Indra. Their sweat resulted into this river and alarmed Indra. He appeased their wrath through good offices of Brahma.

Then there is a legend of Snake, Bamun, who became the Lord of Dun on the summit of Nagdish hill. This legend seems to point to the Naga supermacy on one time. The famous stone at Kalsi near Haripur on the right banbearing the Edict of emperor Asoka may mark the boundary on Northern side.