In the 1990s, researchers established that there are around 1,000 different olfactory receptors in our noses. This astonished scientists, because the variety of receptors in the scent-perception system was many times greater than that in the visual, hearing and taste systems. Moreover, another question was added to the already long list of those to which the answers were unknown: How can we detect more than 10,000 different scents with only 1,000 different receptors?
Our ability to distinguish the various pleasant smells of foods, flowers and drinks is a blessing bestowed on human beings by God.
In 1999, American and Japanese scientists researching this question obtained significant findings about the olfactory system's functioning. According to the results of that research, a scent receptor is able to establish bonds with various scent molecules, which sends a number of scent receptors into action. Continued studies revealed the presence of a very special mechanism in the olfactory system. In the words of Linda B. Buck, one of the researchers in question, this mechanism was a special "alphabet."
As you know, the words and sentences we use consist of letters. For example, the English language alphabet we use to communicate contains 26 letters, which mean nothing on their own. A significant meaning emerges only when they are combined in a specific sequence.
Similarly, an alphabet consisting of receptors is used in the olfactory system. To put it another way, 1,000 different receptors represent 1,000 different "letters." There is no specific receptor responding to every smell in our olfactory region; instead, different scent molecules stimulate specific receptors, which then set specific glomerules in the olfactory bulb into action. This forms a special combination, or code, for the scent. For example, scent A activates communication units 23, 246, 456, and 799 in the olfactory bulb, while scent B does the same for numbers 382, 573, 684, 812 and 1245. These two different codes are then perceived as different smells in the brain's scent cortex. A quick mathematical calculation shows that this mechanism we possess can identify millions of different aromas.
(Figure 16) With the exception of chromosome 20 and the Y chromosome, there are scent-receptor genes in all human chromosomes. The richest chromosome, in terms of scent receptor genes, is chromosome 11.
The reason why the sentence "The kitchen smells of vanilla" has meaning is that the letters in our alphabet are set out in a particular sequence. Similarly, an aroma from the kitchen expressing "vanilla" takes place by means of receptors and glomerules being stimulated in a particular manner.
The brain's scent perception region analyzes the signals from different receptors en masse. The smell which we define as one single perception occurs as the product of 1,000 different receptors. In other words, every receptor is actually part of a mosaic, and a perceptible scent emerges only once all the components of the mosaic have been assembled.
Professor John C. Leffingwell compares the way that receptors give rise to perceptions of smell in the brain to the way that letters in particular combinations form words, notes form works of music, or a binary code gives rise to computer programs. Like every new scientific finding, of course, this discovery represents a major disappointment for evolutionists. It is impossible for a play of Shakespeare's to emerge by chance from letters, or for a work by Mozart to arise from an assembly of notes. It is also impossible for smells to emerge by chance from the olfactory system's "alphabet," which is incomparably more complex. Even the word impossible fails to do justice to its scale.
Therefore, even if evolutionists believe that scent receptors formed by chance, that still does not release them from the quandary in which they find themselves, because these receptors are controlled by some 1,000 genes. To express it even more clearly, scent receptors are produced in the light of a pattern previously encoded in the genes. And scent-receptor genes are distributed throughout all the chromosomes, apart from chromosome 20 and the Y chromosome. (Figure 16) It is impossible for the genetic coding for a single scent receptor form spontaneously, or as the result of chance. If all the rational, conscious humans who lived prior to the 20th century, and were therefore ignorant of how a computer works, were collected together, they could still never write an ordinary computer program. That being so, can one really expect blind, unconscious atoms to write the genetic codes for receptors to perceive the aromas of flowers, fruits and countless chemical substances?
Absolutely not! Scent receptors and perception systems, olfactory cells, and the genes that control them cannot exist in the absence of a Creator Who made them. That Creator is God, "The Lord of the heavens and the Earth and everything between them." (Surat ash-Shu'ara': 24)
The Miraculous Connection in the Olfactory Nerves
One very important property distinguishes olfactory nerve cells from other neurons. Although the hundred billion or so neurons in the brain cannot be replaced as long as we live, the millions of scent receptor cells in the nose live for an average of 45 days. Those that die at the end of that period are replaced by others. The site where new olfactory cells arise is among the basal cells in the olfactory region. Basal cells work literally like a scent-cell factory, constantly and regularly producing new ones.
Under some circumstances, when a heavy blow is received to the head—in a traffic accident, for instance—olfactory cells may be compressed in the ethmoid bone, one of those making up the skull. If the damage is not too great, new cells take over, thus preventing any loss of scent perception. This re-acquisition of the sense of smell has been observed in a great many cases.
How do the new cells unfailingly know where to install themselves? How do they reach their objectives in the olfactory region? How are new receptors able to maintain the communication established by their predecessors with scent molecules, with no loss or error occurring? How is communication between the receptors and the olfactory bulb re-established, with no deficiency or error?
The world of science keenly awaits answers to these and similar questions. What is known at present is the existence of astonishing mechanisms among the cells, the details of which are not known. Even though roughly a million olfactory cells are completely replaced every 45 days, you still perceive the smell of a rose as belonging to a rose. Were any error in the exchange of duties in the olfactory cells to take place, then you would identify a great many scents wrongly, or else be totally unaware of them and be unable to rectify any confusion that would arise. Your olfactory system would constantly mislead you and give rise to serious difficulties. Yet nothing of the sort ever happens. New nerve cells faultlessly take over the functions of the old ones.
Another rather astonishing point is how those new olfactory nerves unerringly find their way to the olfactory bulb. There are no signposts in the nose or brain, and new cells can hardly ask directions. Yet the connections within the olfactory nerves are constantly renewed throughout your life, in such a way as to leave no room for error. This cannot be explained in terms of probability calculations. To claim that the bonds among millions of olfactory nerves came into being by chance is like asserting that the cables constituting the telephone system of a major city were unerringly laid out by the wind, lightning and random coincidences.
No doubt, these are all proofs of the flawless creation and matchless artistry of our Almighty Lord. Every part of the olfactory system, every cell, every molecule and every atom, all behave in the manner inspired in them by Omniscient and Almighty God, ever since the day they were first created. God instructs them how to behave at every moment, right down to the finest detail. This truth is revealed in a verse of the Qur'an:
It is God Who created the seven heavens and of the Earth the same number, the Command descending down through all of them, so that you might know that God has power over all things and that God encompasses all things in His knowledge. (Surat at-Talaq: 12)