Of faith, Engineering and the Human Visual System

Recently, I found a new reason to envy doctors, apart from the higher incomes and the better male/female ratio in colleges. I found out that it is very easy for doctors to have faith. I realized this when I had the chance to attend a seminar on the human visual perception system organized by my school. During the seminar I came to realize just how perfectly engineered the human visual system is. Then another thing hit me, this is just ONE of the thousands of subsystems of the human body, each of which is probably an instrument engineered to perfection to perform its function. Doctors get to study all of this, how could they NOT believe in a higher being, an entity infinitely intelligent which designed all of this.

But I get ahead of myself, I would like to share with you some of what I learned that day. Like most of you know, our eye has a lens at the front which concentrates all light on the “retina” at the back. The retina is a matrix of light detector cells much like you would find inside a digital camera. Here is one of the amazing parts, the retina has a varying density of light detection cells, with highest density concentrated at the portion which receives light from the front 1 degree vision cone, and continuingly decreasing amounts in an arrangement which covers about 200 degrees of horizontal vision. This accounts for the fact that whenever you want to do something visually intensive like reading or threading a needle you look directly AT the target, focusing the light from the target onto that high concentration area. Ever tried to read something that you’re not looking at, try it, it’s impossible. While keeping your eyes on “this”, try to read a few lines above, it’s impossible! Lets look at history, our forefathers thousands of years ago were hunters (daylight hunters, which will factor in later). Hunting animals need excellent peripheral vision, and not surprisingly, we have that. Although we cannot “focus” on anything in our periphery of vision, we CAN sense danger there, in the form of movement. Ever notice how you can sense something moving at your side and suddenly turn your eyes and focus directly on it, that’s your legacy from your hunter grandfathers.

Theres more where that came from, we have, in our retina, 2 main kinds of photoreceptor cells, cones and rods. The cones are responsible for identifying color, whereas rods work only in greyscales. There are further 3 categories of cones responsible for identifying red, green and blue colors, or the so-called RGB colorspace. Only cones are present in the central high-concentration area of the retina, and rods and cons are equally present in the other portions. Also, the cones work only in bright environments and the rods work in low light. The results, two-fold; one, we don’t have very good color perception in the dark (ever noticed how things seem to be in black and white when you get up to go to the bathroom in the middle of the night?), and two, we can’t use our central focusing ability in the dark, therefore it’s much harder for us to recognize objects and forms in the dark than it is in the daylight (like writing). This again doesn’t harm us much, since, like we all know, our ancestors hunted during the day, not during the night like owls and cats.

Finally, and this is the most amazing from a technical point of view, we have a blindspot in each eye. There is a break in the retina where there are no receptor cells, instead, the optic nerve leaves the eye and goes to the brain from this place. We don’t feel this because the blind spots of the two eyes are focused at different areas and the “visual cortex” (the brain’s image processing portion) fills in the blanks. Incredibly, even with only one eye functioning, the visual cortex is able to interpolate the form of the object if the object is connected and its other portions are visible, giving the illusion that the blind spot is not present. So it requires some very careful (although easy) experiments to discover your blindspot. Therefore, the visual cortex is a supercomputer with about 500 million processing elements (neurons) that does alot more infinitely better than the current “state-of-the-art” technology could ever hope to do.

There is so much more just to the eye, but my powers of explanation fail me. Suffice it to say, that there is so much complexity in just the construction of the eye that it could not be an “accident” of evolution. No matter what someone tells me, this was designed with perfection in mind. And therefore I believe that God is present, and he is an engineer. As a friend of mine said to me once, “an engineer is someone who can do something in 10 days at a cost of a hundred euros what a layman would do in a month at a cost of a thousand euros”, according to that definition, God is THE engineer.