The Origin Of Life

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The Origin Of Life

  1. 1. The Origin of Life The origin of life and the origin of the universe are the two basic and fundamental questions, which have not been answered by the scientists. Some scientists speculate that once the answers to these two key questions are found, then the existence of God can be disproved. First let us see what the Qur'an says on the origin of life, particularly the origin of mankind. The Qur'an says: "O mankind! Reverence Your Guardian-Lord, Who created you from a single Person (soul or self) Created, of like nature His (Her) mate, and from them twain Scattered (like seeds) Countless men and women; Reverence God, through Whom Ye demand your mutual (rights), And (reverence) the wombs (That bore you); for God Ever watches over you" Surah Nisaa (Woman), 4: 1 In this verse the creation of mankind is clearly stated. The Bible says that Eve (Hawwa) was created from a rib of Adam. This story is not mentioned anywhere in the Qur'an Majid.
  2. 2. Now let us see what the sciences and the scientists say about the origin of life. SEEDING EARTH WITH ORGANICS Between 4.5 and 3.8 billion years ago, it appears that Earth was bombarded with comets of ice. These comets brought a significant quantity of water to Earth. If comets made a significant contribution to the oceans of primitive Earth, then they played a major role in shaping the environment in which life evolved. Comets may also have contributed to the terrestrial inventory of organic molecules necessary for the origin of life. In 1953 Stanley Miller, a University of Chicago graduate student working under the supervision of the Nobel Prize-winning chemist Harold Urey, showed that amino acids and other organic molecules would form easily and naturally in what was then believed to have been the atmosphere of the early Earth. Simulating this primitive atmosphere with a gas mixture of methane, ammonia and water, Miller introduced an electrical spark (representing, for example, Lightning) and obtained a high yield of amino acids. It has since been shown that in such an atmosphere virtually any energy input (for example, ultraviolet light from the Sun, or shock energy from meteoritic impacts) will lead to the creation not only of amino acids but to the precursors of other important biological molecules. In the traditional view of primitive Earth, these precursor molecules collected in the oceans, forming a warm, dilute "organic soup," on the surface or shorelines of which life evolved.
  3. 3. Most recently consensus among the scientists is that the early terrestrial atmosphere may not have been so biologically accommodating. In this picture, the early atmosphere consisted not of methane and ammonia but mainly of nitrogen and great quantities of carbon dioxide. Under these conditions production of organic molecules is more difficult, and thus environments suitable for the origin of life on primitive Earth would have been more rare. It is believed that the comets may have provided an important extraterrestrial link for the origins of terrestrial life. Giotto, the European spacecraft sent to encounter Haley's Comet in March 1986, pierced the cloud of gas and dust surrounding the comet's core and flew within 600 kilometers (400 miles) of its frozen nucleus. Vega, the Soviet spacecraft plotted the position and trajectory of Haley's nucleus. Both Giotto and Vega showed that comets are full of organic molecules. It now appears that such molecules form inevitably in comets by a process analogous to the Miller/Urey experiment. Miller and Urey used a gaseous mixture, but the experiment will also produce organics when methane, ammonia and water are present in solid form, as ices. Cometary collisions with Earth would necessarily contribute some of these organics to earth's prebiotic inventory. However, we don't know what fraction of Cometary organics would survive the high temperatures and pressures associated with the resulting explosion and crater excavation. Cometary water (Ice) would evaporate, enter the atmosphere as steam and eventually rain out, but the Cometary organics might well be destroyed. The intense bombardment of early Earth may have resulted in an "impact frustration" of the origins of life. Large impacts would have been catastrophic for local environments, and the extreme temperatures generated by the violent collisions may have effectively sterilized vast expanses. Moreover, the huge explosions would have vaulted enormous quantities of dust into the atmosphere. There may even have been enough debris to envelop Earth in a dust cloud, blocking sunlight and creating conditions like those envisioned in the "nuclear winter" hypothesis proposed by David Grinspoon and Carl Sagan. Such an era of inhospitable conditions would mean that
  4. 4. the time available on the early Earth for the origin of life was even shorter than previously believed. Scientists are speculating that if the terrestrial evolution of life did occur very rapidly, then the possibility increases that life may have arisen on Mars during its apparently brief, comparatively Earthlike youth. This could be verified by the Soviet and US missions to Mars in this decade. THE EVOLUTION OF LIFE As mentioned before few question are more fundamental than that of how life came to exist here. How was it possible for a collection of rocks and volcanic gases to give rise to something as complex as the human brain? Many gaps in our knowledge remain. The chemical basis for all life on the Earth is the interaction between carbon atoms. When two carbon atoms approach each other, they begin to share a pair of outer electrons-one from each atom. This sharing creates a bond that holds the atoms together. Carbon chains form the basis for all living matter on earth, from the simplest amino acids to incredibly complex molecules like DNA (deoxy ribonucleic acid). The simplest carbon chains- the ones that form the basic building blocks for more complex organic molecules that make up proteins-are called amino acids. All told, there are more than 100 amino acids to be found in living systems on earth, though just over 20 are required for adequate human nutrition. The question is whether it is possible to assemble some of these chemical building blocks of life from ingredients of the primitive atmosphere.
  5. 5. Since the time of Urey-Miller (1953), amino acids have been produced using ultraviolet radiation instead of an electrical discharge. Different chemical mixtures for simulating the early atmosphere have also been tried. In fact, during the last 30 years chemists working on the origins of life have been able to produce quite complex carbon chains using improved versions of the Urey-Miller experiment. Cyril Ponnamperuma of Sri Lanka at the University of Maryland has been able to derive the complex building blocks of DNA in this way. It seems, then, easy to account for the accumulation of the basic building blocks of life very early in the history of the earth. The problem comes in the next step- the joining together of these building blocks into what we call life, a system capable of its own development and reproduction. In the early part of this century, people used to talk about finding the "missing link" in evolution, by which they meant the link between ape and man. Now the evolutionary tree of Homo Sapiens has been worked out in some detail, however, it would be much more appropriate to apply the term "missing link" to the gap between amino acids and the first living cell. How did the cell emerge? What physical processes shaped its creation? How did the laws of chemistry and physics join to produce a biological organism? These questions touch on the very heart of the problem of life itself. And over the past few decades, scientists have come to understand some of life's basic requirements. A cell needs three different chemical constituents: proteins, to carry out the biochemical functions; nucleic acids (RNA and DNA) to pass on genetic information to the next generation; and lipids (fats) to form a membrane to protect the interior of the cell from its environment. The problem of how the simple molecules one might expect to find in the primordial soup could organize themselves into a functioning cell is the central question faced today by researchers who probe the origins of life. Scientists have the parts and are beginning to understand how they fit together into a complex system. At the moment, however, no one has managed to assemble life in the laboratory.
  6. 6. WHAT THE SCIENTISTS SAY? Human life cannot exist without a star such as our sun. Cambridge Astrophysicist Brandon Carter says that the life of a star is a constant struggle between the forces of gravity which strive to cause the star to collapse in upon itself, and the forces of electromagnetism which work against gravity and struggle to keep the star from collapsing. Carter observed that the balance of power between these two forces is so incredibly fine-tuned that it is quite difficult to conceive of this balance being the result of coincidence alone. For instance, if as the universe were forming, the strength of the force of gravitation had varied by as little as a mere one part in 10,000 billion, billion, billion, billion ( 1 part in 10 to the power of 40 or 1 followed by 40 zeros), this delicate balance would have been destroyed and stars such as our Sun would never have formed. Since life as we know it is contingent on the existence of stars such as the Sun, it follows that the existence of the human race also rests on this precarious balance. In other words, the existence of life on Earth hangs on a thread far slender than that, which held the sword of Damocles. Freeman Dyson ( a Professor of Physics at the Institute for Advanced Study, Princeton University, Princeton, New Jersey 08540)) has pointed out another such coincidence. In the nucleus of an atom, protons and neutrons are held together by a powerful cohesive force known as the strong nuclear force. Dyson has noted that if as the universe were forming this force had been only slightly weaker than what it is, protons and neutrons would not be able to hold together and atoms as we know them would never have formed. Conversely, if the force had been minutely stronger, it would then have been possible for protons to stick together, and long ago all of the free protons in the universe would have been mopped up like so much glue, preventing the formation of atoms and stars and people. The list of such coincidences goes on and on.
  7. 7. The late Sir Fred Hoyle the well known British Astrophysicist, along with California Institute of Technology astrophysicist William A. Fowler, has pointed out that oxygen and carbon, two of the most important elements on which life on Earth is based, are designed almost perfectly so that they will be produced in the interiors of stars in equal amounts. If this was not the case, and one or the other predominated in the universe, the development of life would once again have been precluded. Earlier it was shown that the life began in the primordial soup of Earth's ancient seas is a questionable hypothesis. Yet currently it is the accepted wisdom in science that life began in the primordial soup and was the result of a completely random orchestration of events. The justification for this view is that given enough time and enough accidental permutations of chemicals in such a primordial broth, it is possible that any complexity might have arisen. Similarly, like-thinkers pointed out that given enough time, a large work force of monkeys with an equally large number of typewriters could sooner or later come up with all the works of Shakespeare. Hoyle says this view is realistically impractical. Mathematician David Osselton points out the basic mathematics behind the notion that given enough time a group of monkeys would eventually manage to type the works of Shakespeare may be simple and sound, but the sheer enormity of such a task makes it meaningless as an explanatory principle. According to Osselton's calculations it would take a million million monkeys roughly a million million years to type out only the name of William Shakespeare. And to obtain a paltry two lines from one of Shakespeare's plays would require 10*150 ( 10 to the power of 150 or 1 followed by 150 zeroes) strokes on a simplified fifty-character typewriter, or billions of billions of time more than the number of atoms in the whole universe. Osselton concludes, "The Idea that in the fullness of time random events will ineluctably come up with the right combination is less potent than has been commonly supposed."
  8. 8. Hoyle invokes the same argument: It is known that a living cell has a chain of amino acids, of which there are twenty different kinds. The function of these amino acids is in turn dependent upon 1,000 to 2,000 highly specialized enzymes. Hoyle postulates that for an enzyme to work by the amino acid chain, assuming its correct configuration in space, at least twenty to thirty key amino acids must be "right." According to Hoyle's calculations, the probability of a thousand different enzymes coming together in just the right way over the course of Earth's several billion years of history to form one living cell is a staggering 10*40,000 to 1. Francis Crick, who shared a Nobel Prize for his work on the structure of DNA, likewise concluded, "An honest man, armed with all the knowledge available to us now, could only state that in some sense, the origin of life appears at the moment to be almost a miracle, so many are the conditions which would have had to have been satisfied to get it going." Further, on noting that random processes tend to destroy order, and intelligence shows itself most effectively in arranging things and producing order out of chaos, Hoyle concludes that the complexity of life indicates that the universe itself is intelligent, and that it is this intelligence, or hierarchy of intelligences, that first wrought the order in matter that resulted in living things. Currently, it is known that the evolution of life on Earth is not a gradual process taking place in discrete steps but is most often an abrupt and sudden process, with new designs and advances in organisms appearing quite suddenly, and this is known as "punctuated equilibria." Because of the similarity of processes between the universal intelligence and biological life on Earth, Hoyle concludes that perhaps there is a connecting chain of
  9. 9. intelligence, extending downward from the intelligence of the universe as a whole to the intelligence of those hierarchies of software whose activities are indistinguishable from nature "by a series of further links to humans upon the Earth."

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