The Story of a Moment's Communication

Everybody can remember a time when his or her eyes met with an acquaintance's eyes and they greeted one another. Would you believe that this communication of a brief moment has a long story?

Let's assume that on a certain afternoon two men are situated apart from one another. In spite of their close friendship, they have not yet recognized one another. One of these men, turning his head in the direction of his friend, whom he has not yet recognized, starts a chain of biochemical reactions: the light reflected from the body of his friend enters the eye lens at a speed of ten trillion photons (light particles) per second. Light travels through the lens and the fluid that fills the eyeball before falling on the retina. On the retina there are about hundred million cells called "cones" and "rods". Rods differentiate light from dark and cones perceive colors.

Depending on the external objects, varying light waves fall on different places on the retina. Let's think about the moment the person in our assumed situation sees his friend. Some features on his friend's face cast different intensities of light on his retina e.g. darker facial features such as eyebrows would reflect light at much lower intensities. Neighboring cells on the retina, however, receive stronger intensities of light reflected from the forehead of his friend. All of his friend's facial features cast waves of various intensities on the retina of his eye.

What kind of stimuli do these light waves provoke?

The answer to this question is, indeed, very complicated. Nevertheless, the answer has to be examined to fully appreciate the extraordinary design of the eye.

The Chemistry of Seeing

When photons hit the cells of the retina, they activate a chain reaction, rather like a domino effect. The first of these domino pieces is a molecule called "11-cis-retinal" that is sensitive to photons. When struck by a photon, this molecule changes shape, which in turn changes the shape of a protein called "rhodopsin" to which it is tightly bound. Rhodopsin then takes a form that enables it to stick to another resident protein in the cell called "transducin".

Prior to reacting with rhodopsin, tranducin is bound to another molecule called GDP. When it connects with rhodopsin, transducin releases the GDP molecule and is linked to a new molecule called GTP. That is why the complex consisting of the two proteins (rhodopsin and transducin) and a smaller chemical molecule (GTP) is called "GTP-transducinrhodopsin".

The new GTP-transducinrhodopsin complex can now very quickly bind to another protein resident in the cell called "phosphodiesterase". This enables the phosphodiesterase protein to cut yet another molecule resident in the cell, called cGMP. Since this process takes place in the millions of proteins in the cell, the cGMP concentration is suddenly reduced.

How does all this help with sight? The last element of this chain reaction supplies the answer. The fall in the cGMP amount affects the ion channels in the cell. The so-called ion channel is a structure composed of proteins that regulate the number of sodium ions within the cell. Under normal conditions, the ion channel allows sodium ions to flow into the cell, while another molecule disposes of the excess ions to maintain a balance. When the number of cGMP molecules falls, so does the number of sodium ions. This leads to an imbalance of charge across the membrane, which stimulates the nerve cells connected to these cells, forming what we refer to as an "electrical impulse". Nerves carry the impulses to the brain and "seeing" happens there.

In brief, a single photon hits a single cell and, through a series of chain reactions, the cell produces an electrical impulse. This stimulus is modulated by the energy of the photon, that is, the brightness of light. Another fascinating fact is that all of the processes described so far happen in no more than one thousandth of a second. Other specialized proteins within the cells convert elements such as 11-cis-retinal, rhodopsin and transducin back to their original states. The eye is under a constant shower of photons, and the chain reactions within the eye's sensitive cells enable it to perceive each one of these photons.

The process of sight is actually a great deal more complicated than the outline presented here would indicate. However, even this brief overview is sufficient to demonstrate the extraordinary nature of the system. There is such a complicated, finely calculated design inside the eye that chemical reactions in the eye resemble the domino shows in the Guinness Book of World Records. In these shows, tens of thousands of domino pieces are so strategically placed that tipping the first piece activates the entire system. In some areas of the domino chain, many apparatuses are installed to start a new sequences of reactions, e.g. a winch carrying a piece to another location and dropping it exactly at the place necessary for a further sequence of reactions.

Of course, nobody thinks that these pieces have been "coincidentally" brought to their precise locations by winds, quakes or floods. It is obvious to everyone that each piece has been placed with great attention and precision. The chain reaction in the human eye reminds us that it is nonsense to even entertain the thought of the word "coincidence". The system is composed of a number of different pieces assembled together in very delicate balances and is a clear sign of "design". The eye is created flawlessly.

Biochemist Michael Behe comments on the chemistry of the eye and the theory of evolution in his book Darwin 's Black Box:

Now that the black box of vision has been opened, it is no longer enough for an evolutionary explanation of that power to consider only the anatomical structures of whole eyes, as Darwin did in the nineteenth century (and as popularizers of evolution continue to do today). Each of the anatomical steps and structures that Darwin thought were so simple actually involves staggeringly complicated biochemical processes that can not be papered over with rhetoric.

Beyond Seeing

What has been explained so far is the first contact of photons, reflected off a friend's body, with a man's eye. The retinal cells produce electrical signals through complicated chemical processes as described above. In these signals there exists such detail that the face of the man's friend in the example, his body, hair color and even a minute mark on his face have been encoded. Now the signal has to be carried to the brain.

Nerve cells (neurons) stimulated by retinal molecules show a chemical reaction as well. When a neuron is stimulated, protein molecules on its surface change shape. This blocks the movement of the positively charged sodium atoms. The change in the movement of the electrically charged atoms creates a voltage differential within the cell, which results in an electrical signal. The signal arrives at the tip of the nerve cell after traveling a distance shorter than a centimeter. However, there is a gap between two nerve cells and the electrical signal has to cross this gap, which presents a problem. Certain special chemicals between the two neurons carry the signal. The message is carried this way for about a quarter to a fortieth of a millimeter. The electrical impulse is conducted from one nerve cell to the next until it reaches the brain.

These special signals are taken to the visual cortex in the brain. The visual cortex is composed of many regions, one on top of the other, about 1/10 inch (2.5 mm) in thickness and 145 square feet (13.5 square meters) in area. Each one of these regions includes about seventeen million neurons. The 4th region receives the incoming signal first. After a preliminary analysis, it forwards the data to neurons in other regions. In any phase, any neuron can receive a signal from any other neuron.

This way, the man's picture forms in the visual cortex of the brain. However, the image now needs to be compared to the memory cells, which is also done very smoothly. Not a single detail is overlooked. Furthermore, if the friend's perceived face looks slightly more pale than normal then the brain activates the thought, "why is my friend's face so pale today?"

Greeting

That's how two separate miracles happen within a period of time less than a second, which we refer to as "seeing" and "recognizing".

The input that arrives in hundreds of millions of light particles reaches the mind of the person, is processed, compared to the memory and enables the man to recognize his friend.

A greeting follows recognition. A person deduces the reaction to be given to acquaintances from within the memory cells in less than a second. For example, he determines that he needs to say "greetings" upon which the brain cells controlling facial muscles will command the move that we know as a "smile". This command is similarly transferred through nerve cells and triggers a series of other complicated processes.

Simultaneously, another command is given to the vocal cords in the throat, tongue and the lower jaw and the "greetings" sound is produced by the muscle movements. Upon release of the sound, air molecules start traveling towards the man to whom the greeting is sent. The auricle gathers these sound waves, which travel at approximately twenty feet (six meters) per one fiftieth of a second.

The vibrating air inside both ears of that person rapidly travels to his middle ear. The eardrum, 0.30 inch (7.6 millimeter) in diameter, starts vibrating as well. This vibration is then transferred to the three bones in the middle ear, where they are converted into mechanical vibrations that travel to the inner ear. They then create waves in a special fluid inside a snail shell-like structure called the cochlea.

Inside the cochlea, various tones of sound are distinguished. There are many strings of varying thickness inside the cochlea just as in the musical instrument, the harp. The sounds of the man's friend literally play their harmonies on this harp. The sound of "greetings" starts from a low pitch and rises. First, the thicker cords are rattled and then the thinner ones. Finally, tens of thousands of little bar-shaped objects transfer their vibrations to the auditory nerve.

Now the sound "greetings" becomes an electrical signal, which quickly travels to the brain through the auditory nerves. This journey inside the nerves continues until reaching the hearing centre in the brain. As a result, in the person's brain, the majority of the trillions of neurons become busy evaluating the visual and audio data gathered. This way, the person receives and perceives his friend's greeting. Now he returns the greeting. The act of speaking is realized through perfect synchronization of hundreds of muscles within a minute portion of a second: the thought that is designed in the brain as a response is formulated into language. The brain's language centre, known as Broca's area, sends signals to all the muscles involved.

First, the lung provides "hot air". Hot air is the raw material of speech. The primary function of this mechanism is the inhalation of oxygen-rich air into the lungs. Air is taken in through the nose, and it travels down the trachea into the lungs. The oxygen in the air is absorbed by the blood in the lungs. The waste matter of blood, carbon dioxide, is given out. The air, at this point, becomes ready to leave the lungs.

The air returning from the lungs passes through the vocal cords in the throat. These cords are like tiny curtains, which can be "drawn" by the action of the small cartilages to which they are attached. Before speech, the vocal cords are in an open position. During speech they are brought together and caused to vibrate by the exhaled air passing through them. This determines the pitch of an individual's voice: the tenser the cords, the higher the pitch.

The air is vocalized by passing through the cords and reaches to the surface via the nose and mouth. The person's mouth and nose structure adds personal properties unique to him. The tongue draws near to and away from the palate and the lips take various shapes. Throughout these processes, many muscles work at great speed.

The person's friend compares the sound he hears to others in his memory. By comparing, he can immediately tell if it is a familiar sound. Therefore, both parties recognize and greet each other.

All the above takes place during two friends noticing and greeting one another. All of these extraordinary processes happen at incredible speeds with stunning precision, of which we are not even aware. We see, hear and speak so very easily as if it is a very simple thing. However, the systems and processes that make them possible are so unimaginably complex.

This complex system is full of examples of unparalleled design that the theory of evolution cannot explain. The origins of vision, hearing and thinking cannot be explained by the trust of evolutionists in "coincidences". On the contrary, it is obvious that all of them have been created and given to us by our Creator. While the human cannot even understand the working mechanism of systems that enable him to see, hear and think, the infinite wisdom and power of God Who created all these from nothing is apparently obvious.

In Qur'an, God invites humans to ponder this and to be thankful:

God brought you out of your mothers' wombs knowing nothing at all, and gave you hearing, sight and hearts so that perhaps you would show thanks. (Qur'an, 16:78)

Another verse states:

It is He Who has created hearing, sight and hearts for you. What little thanks you show! (Qur'an, 23:78)