Letters

Human eye

It was with amusement that I read Mr. Bartholomew’s recent short homily on evolution (science) and intelligent design (creationism) which focussed on the eye. It demonstrates a lack of understanding of the physiology and anatomy of the eye (and cameras).

The human eye is far from being intelligently designed. Before the light strikes the nerve endings receiving the light it must pass through a layer of blood vessels and neurons. Those nerve endings face backwards, away from the light source, so by the time the light reaches the nerve receptors it has been degraded. The main nerve creates a blind spot as it passes back through the receptive material of the eye. The human eye also has relatively poor night vision compared to many other species.

The eagle eye is much more "intelligent." It does not have blood vessels in the way of the receptors, which face forward. Nourishment is provided by the pecten, which among its other attributes can detect magnetic fields (humans would never get lost if our eyes could do this!). The nerves come in at the back of the eye and do not cover the receptor ends. The eagle has five times as many neural receptors and two focal points for better distance and tracking vision (a trait that both hunters and gamers would appreciate).

Eagles that have faulty vision tend to starve to death and thus do not pass on their bad genes. To survive, healthy eagles require good natural vision. Humans, between 75 and 90 per cent according to source, have some form of visual impairment (short or long sighted, astigmatism, et al).

Light is but one section of the electro-magnetic wave length spectrum. Other animals can see ultra-violet, some see (or sense) infra-red. Cameras, Mr. Bartholomew’s mechanical comparison, are able to ‘see’ these wave lengths, are able to see galaxies billions of miles away, to see microbes and organisms invisible to the human eye, can ‘see’ at night (from which: night vision goggles).

The human eye is far from being a "superb instrument," adequate, but hardly the height of perfection. We would all be better off with the eye of an eagle (or some other bird of prey).

 

Jim Miles, Vernon

 

 

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