Chirality or Sidedness in Nature
HAT IS SIDEDNESS, what significance does it possess if any and why sidedness at all, are the questions to which we shall presently turn our attention. When moving in circles whether we begin to turn from right to left, or left to right, the quality of this exercise is not in the least altered in whichever direction we initiate the turn. If we pick up an object with our right hand or pick it up with our left, so long as it is lifted the question of right or left loses significance. The question of right or left will acquire significance only if we understand its underlying wisdom. But surprisingly, both in Islamic teachings and in some manifestations of natural laws, sidedness seems to be rigidly enforced without any apparent reason for its preference. In the chapter Life in the Perspective of Quranic Revelation we briefly mentioned that many verses of the Holy Quran speak of sidedness with a religious significance. This Quranic attitude is further elaborated to some detail in many traditions of the Holy Prophetsa which instruct the believers as to how they should conduct themselves in their everyday social and religious practices. They display a decided trend in favour of the right over the left.
Why such partiality in matters so trivial, as the mere preference of one side over the other, is a question intriguing enough in its application to religious teachings. But when addressed to a similar universal phenomenon of sidedness in nature, the enigma assumes astronomical proportions. Religious instructions are invariably dictated by a conscious human mind, or Divine teachings. No such Conscious Creator is recognized by the secular scientists to have designed any code of natural conduct. Why then this intriguing similarity between religion and nature in the area of sidedness? If not due to a common origin, could it be reasonably dismissed as mere coincidence? But that is not all. The more we study the manifestations of sidedness in nature, the more we are overwhelmed by the element of wonder it generates. There is no known scientific rationale for its existence. Why nature should display such selective propensity of preferring one side over the other is a question which has not been answered until now and may yet remain unanswered for many a decade to come.
It should be worthy of note here, that according to the Quran every natural behaviour should be rationally explainable. The Quran categorically rules out any scenario of creation which is haphazard, disorderly or accidental. Hence, if not today, the dawn of that tomorrow may not be too far away when scientists will be able to fathom the deep underlying reasons beneath all expressions of sidedness in nature, however shallow they may appear at present.
Before proceeding further, it seems appropriate to explain at some length the phenomenon of sidedness, or chirality, as found operative in nature. It can easily be understood with reference to some group displays of children which highlight the excellence of their physical training. Children of some groups organized in circles of equal number are required to run clockwise while those of some other groups are instructed to run counterclockwise. To enhance the spectacular effect they are generally so paired that if one of the pairs runs in one direction, then the other runs in the opposite one. Visualize just such a pair and you will grasp the meaning of sidedness or chirality in scientific terms. Although similar in all other respects, the image of the group moving from right to left cannot be superimposed on the group moving from left to right because of the opposite direction of their movement. Likewise, though all molecules spin, all do not spin in the same direction. Some move from right to left, while others do so from left to right. Some compounds of exactly the same chemical formula may contain both the right spinning and the left spinning molecules suspended together in a single solution; while some others are composed only of such molecules as move in just one direction. But chirality is not confined to the molecular level alone, even the tiniest of subatomic particles display chirality.
HE EVIDENCE of chirality in nature came to light only some one hundred and fifty years ago. It was Louis Pasteur, the great French scientist who discovered chirality in the spin of molecules in 1848. It is a great tribute to his exceptional intelligence and keen observation that while examining a certain salt of tartaric acid he noticed that there were two types of crystals, each a mirror image of the other. He carefully separated the two, dissolved them in water and made a beam of light pass through the solution. He was surprised to discover that the polarized light was rotated differently by the two specimens. One was rotated clockwise and the other anticlockwise. This clearly meant that the molecules of the two separated specimens of tartaric acid were either spinning to the right or to the left—neither could be superimposed on the other. This was the first ever case of chirality observed by scientists at the elemental level.1
Another singularly significant discovery in the same field was made yet again by Pasteur in 1857. One day he noticed the growth of a mould in a chemical solution lying in a jar. Instead of throwing away the solution as contaminated, he made a beam of light pass through it to examine the effect, if any, of that mould on the solution. He was astounded to discover that the solution, though inactive in relation to light prior to its contamination, had suddenly become active and started polarizing light. It was inactive in relation to light for the simple reason that it was composed of an equal number of right spinning and left spinning molecules each neutralizing the other's effect on light. Hence the polarity displayed by the contaminated specimen could only mean that the mould had eaten up only such molecules as spun in the same direction and left completely untouched those which spun in the opposite. One mystery was thus resolved but only after having given birth to another much more complex one. How could a mere mould detect the spin of molecules with such unfailing exactness and why was it at all partial to the molecules spinning in any specific direction? These were the questions which baffled the mind of Pasteur then and still baffle the minds of scientists today. For how long they remain unanswered, the scientists know not. The magnitude of the dilemma is enormous. The molecules of any element or compound, right spinning or left spinning, share exactly the same chemical and physical properties. What or who dictates their propensity to spin in any particular direction is a brain-twister enough, but when it comes to the most uncanny ability of life to detect which molecules are spinning in which direction, the question acquires bizarre astronomical proportions. None of the five senses bestowed to man are equipped with any known mechanism which can determine the spin of molecules. The spinning molecules leave no imprint on the property of matter to become detectable through human sensory organs. But what of moulds which have no known sensory organs; all they have is a diffused sense of awareness?
This amazing tale of chirality in nature does not end here. It just begins. Since the time of Pasteur, research on chirality has made tremendous progress and many more extremely perplexing examples have come to light testifying that chirality can be unmistakably detected by different species of life.
By now chirality is discovered to operate at every level of material existence. Yet the manner of how and why it so behaves is far from understood. Until 1957 it was believed that the four fundamental forces which govern the interaction of elementary particles were parity conserving. This simply means that all particles at elementary level had chiral-symmetry. However, in 1957 Chien-Shiung Wu and her colleagues at Columbia University discovered that beta particles emitted from radioactive nuclei did not display chiral-symmetry. The left-handed electrons far outnumbered the right-handed ones. It was further discovered that the tiniest subatomic particles, neutrinos and anti-neutrinos, which are electrically neutral and move at the speed of light, also display a certain spin. But unlike electrons which predominantly prefer left-handed spin, anti-neutrinos are always partial to the right-hand. The contrary is not found in nature. No one knows why chiral-asymmetry exists at such fundamental levels of existence at all.
Many hypotheses are being presented but most are found to be simply preposterous when examined more minutely. However, there is one suggestion which seems to have provided scientists with a clue to the factor possibly at work at the most rudimentary level of chirality in nature. Yet at this level, it is too ethereal to be demonstrated or verified. It is related to a theory which unifies the weak and electromagnetic forces first propounded by Dr. Abdus Salam, Steven Weinberg and Sheldon Glashow in 1960. That theory predicted a new electroweak force which does not conserve parity. This disparity according to scientists could possibly be responsible for the right-handed spin of anti-neutrinos and left-handed spin of neutrinos, as well as that of electrons. But this weak electric force cannot be contemplated as the causative factor to produce the right sided or left sided behaviours at all other levels of chirality. The behavioural difference between the two sometimes perplexes scientists, particularly in relation to the role they play in biotic evolution. The problem is further compounded when we observe that the two right sided and left sided components of exactly the same chemical formula exert a completely different influence on life in odd ways. The following are some fascinating examples:
Limonene is a compound found both in lemons and oranges. There is not the slightest difference in their chemical formula, yet the spin of limonene molecules in lemons is invariably opposite to the molecular spin of limonene found in oranges. Limonene in lemons is always right spinning while in oranges it is always left spinning. How on earth could lemons and oranges always pick the limonene of a specific spin for their consumption while the difference between their limonene is merely that of molecular spin? It needs to be emphasized yet again that both the right sided and left sided specimens of limonene contain exactly the same chemical and physical properties. How the olfactory glands of the human nose can ever detect the difference of the spin in oranges and lemons and ascribe to them completely different smells is absolutely astounding. Of course there has to be some reason but as yet we cannot identify it.
Another example relates to the influence of chirality on life of a rather sinister nature. This came to light in 1963 when a drug, thalidomide, was introduced by a pharmaceutical company for the cure of morning sickness in pregnant women. Many were cured, but for many others it proved disastrous. Horrible congenital defects were found in the babies born to some mothers treated by the same drug. A subsequent intensive research revealed that the pharmaceutical company which manufactured thalidomide had inadvertently manufactured two types of thalidomide compounds of the same formula. While the molecules of one type spun in one direction, those of the second type spun in the other. While one type cured morning sickness without producing any adverse effect on the embryo, the other type produced the most horrible congenital deformities instead of curing the morning sickness. The most profound side-effect was the deformities of the lower limbs among the infants born under its influence.
Another intriguing case of the detection of the spin and the preference of one spin over the other is found at the most fundamental level of life. Although there were several hundred amino acids freely available in the primordial soup from which such proteins were created as made the fundamental bricks of life (DNA and RNA), 'nature' selected only twenty amino acids out of them and they were all left spinning!
In the case of selecting molecules for building sugars however, the choice was reversed. The molecules of all the four different forms of sugars responsible for the provision of energy to all forms of life are, without exception, right spinning. This means that all natural sources of sugar available to life, like sugar cane, beet root, fruit, etc., manufacture sugar consisting only of right spinning molecules.
Nevertheless, a successful experiment was conducted a few years ago for synthesizing sugar comprising only left spinning molecules. It was discovered that this artificially synthesized sugar, though exactly the same in taste, chemical properties and cooking behaviour, was totally rejected by the human digestive system. Not a molecule was assimilated. This gave rise to the bizarre idea of manufacturing sugar consisting of only left spinning molecules on a commercial scale, not only for the benefit of diabetics but also for the pleasure of gourmands and gluttons. They could consume mountains of sugar without the fear of accumulating even a molehill of fat. The only snag is that, at present, the cost of manufacturing left spinning synthetic sugar is prohibitive. A mountain of money would be needed to produce a mere molehill of such sugar. Perhaps only the royal highnesses of oil rich monarchies sitting upon mountains of oil wealth could afford this luxury.
The apparently arbitrary preference for right or left also manifests itself in many other ways. Most humans are right-handed and the arrangement of the heart and liver is universally left sided and right sided respectively, barring a few rare individual exceptions of course. Roger A. Hegstrom and Dillip K. Kondepudi in their jointly authored article The Handedness of the Universe published in Scientific American, January 1990, present many examples of handedness in nature without any apparent reason for preference. While observing that most people are right-handed, they fail to recognize any reason
'...why right- and left-handed persons are not born in equal numbers.' 2
But it is not a prerogative of the human race alone to display definite trends with regards to handedness.
On partiality to sidedness as found in the animal kingdom and vegetative behaviour, they write:
'Right-handed or dextral shells dominate—on both sides of the Equator. Among these right-dominated animals, left-handed individuals exist only as a result of mutations, which appear with a frequency ranging from about one in hundreds to one in millions, depending on the species.' 3
In contrast to them, the lightning-whelk of the Atlantic coast are predominantly left-handed. In plants, the honeysuckle winds around its support in a left-handed helix while the bindweed prefers winding from right to left. Even in bacteria some of their colonies spiral from right to left yet as the temperature increases they reverse the spiral direction to left-handed turns. 3
These are but a few cases. At every level of evolution we find many other outstanding examples of how life displays partiality to the spin of molecules. Their study excites wonderment and leaves one bewildered. There has to be a Conscious All-Wise Supreme Selector who made choices at every stage of decision making or one has to ascribe this role to the haphazard vagaries of blind nature!
E FEEL that at the end, the purpose of this exercise needs to be emphasized once again. The basic issue of discussion is whether revelation can play any role in transferring information from the realm of the unknown to the realm of the known. Every discussion under different titles in this treatise is invariably related to this issue. In this chapter the relevance may not have been clearly understood, hence the need for further elaboration of this point. We have already pointed out that in the entire comity of religions Islam stands out in its emphasis on sidedness in religious behaviour and conduct. We respectfully draw the attention of the reader that in all other religions the opposite number of right is wrong, not left.
N ISLAM however, the word 'right' is not employed exclusively to indicate goodness, it is also employed to indicate 'the side' literally. As such, in this context the term 'right' is not used against 'wrong'; it is used against 'left'. This is clearly sidedness. In many Quranic verses right is decidedly mentioned in its preference over the left. It is these verses which must have provided the guidelines for the Holy Prophetsa to direct the believers to prefer right over left in day-to-day religious conduct. His established practice was to always commence good things from his right side or by his right hand. The believers are told to perform ablution, for instance, with the right hand first. When they wear their shoes, they should insert the right foot first. In the seating arrangements at a table, the guest of honour is seated on the right side of the host. At the birth of a child in Islam, the Muslim call for prayer (Azan) should be whispered into the right ear before whispering Al-Takbir in the left. Such instructions were not accidental but were specific down to the minutest detail. According to his instructions and his own personal consistent example, the Muslims are required to always use the right hand for touching and holding clean things, while the rest are left to the left hand. Hence when a Muslim shakes hands with others he is expected to do so with full confidence that he is offering a clean hand.
Instructions such as these clearly indicate that the concept of sidedness in religious and social behaviour were purposefully incorporated in Islam. It is also in this sense that the prophecies concerning the future of mankind use the terms 'rightist' and 'leftist'. Hence the political and economic division in the contemporary age, based on the rightist philosophy or the leftist philosophy, tally clearly with the Quranic prophecies regarding the future of mankind.
Why is it that it is Islam alone which emphasizes sidedness so strongly while other Divinely revealed religions do not even mention it?
In answer to this question, it should be well understood that according to the Quran, the age of all other religions had come to an end with the dawn of Islam. Polarity and sidedness are the trends which had not yet been born in human affairs in the age prior to it. It was only Islam which was to address the people of an age where polarity and sidedness were to become common coinage in matters of expression.
Looking at it from this angle, the evidence of sidedness in day-to-day behavioural matters was in a way prophetic, that man was about to be ushered into that advanced age when sidedness would acquire new depths and new dimensions. This is exactly what has come to pass. Little did the man of that age know that not only in matters of political and economic divisions, but also in the domain of science, sidedness would acquire such importance as could never be imagined in any previous era.
- FESSENDEN, R.J., FESSENDEN, J.S. (1982) Organic Chemistry. 2nd ed. PWS Publishers. Willard Grant Press. Massachusetts, p.139
- HEGSTROM, R.A., KONDEPUDI, D.K. (January, 1990) The Handedness of The Universe. Scientific American: pp.98–99
- HEGSTROM, R.A., KONDEPUDI, D.K. (January, 1990) The Handedness of The Universe. Scientific American: p.99