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  Section: Introduction to Botany » The Origin of Life
 
 
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A Modern-day Theory

 
     
 
Content
The Origin of Life
  The Theory of Spontaneous Generation
  Life Viewed Through the Microscope
  A Modern-day Theory

We are brought back, then, to modern-day thinking, which tells us that all living things are products of living things. At the same time, however, we realize that there was a time when life did not exist on Earth and that there had to be a beginning. This leads us to the following understanding: life does not arise spontaneously in the world as we know it today, but in the primordial world, when conditions were different, life arose from a nonliving precursor. It is important to emphasize that world conditions were different from those we know today. Specifically, the atmosphere at that time was either nearly or completely devoid of oxygen.

Before continuing, it is also important to make clear that theories regarding the origin of life reside in the realm of educated speculation. It is contended that organic molecules were formed in the primordial sea or in the atmosphere; that these molecules accumulated, persisted, and got together in clusters; and that molecules formed that were able to govern both their own replication and the formation of other molecules. If this sounds like the contention of an exalted imagination, keep in mind that this process occurred in a world having conditions different from those of the world today. There was no decay, because decay is the function of organisms; there was little or no oxygen; and molecules did not tend to break down in being oxidized. Here, an argument may be made that without oxygen, there was no ozone layer; and that without ozone in the upper atmosphere, ultraviolet light would ; have been able to penetrate to the Earth’s surface; and that ultraviolet radiation is not compatible with life. This objection is countered by the fact that ultraviolet light is not able to penetrate water, and life is believed to have begun in the water. So long as there was no oxygen in the atmosphere, life was confined to the sea.

Stanley Miller’s experiment is significant to this hypothesis. In 1953 he constructed an apparatus intended to simulate the ancient atmosphere in the neighborhood of a volcano. This apparatus included a mixture of gases, hydrogen, ammonia, methane, and water. He subjected this mixture to heat and electrical discharges, and, in time, determined that a number of amino acids had formed. This was significant because until this time, it was believed that amino acids were made only by organisms. Friedrich Wohlor’s (1800-1882) successful synthesis of urea in 1828 provided another example of the synthesis of an organic molecule not made by an organism.

Laboratory observations such as those of Miller and Wohler are far from the creation of life. Nor do they fully explain how life came into being. Yet one must ask what we have to take the place of such observations. The theological explanation is simple enough: God made life. But that is not an explanation. It just makes an explanation unnecessary. Thus, it is not the approach taken in this text.

Laboratory observations, then, demonstrate neither the formation of deoxyribonucleic acid (DNA) nor the formation of chlorophyll, the green stuff that can trap light energy and use it in the manufacture of starch. All one can say is that these things did happen somewhere along the line. When the capacity of photosynthesis came into that primordial ooze that we call blue-green algae, oxygen was liberated to the atmosphere. The stage was thus set for the emergence of terrestrial life. It is difficult to conceive of the events that were to follow; events that would lead eventually to tears and laughterevents that unfolded over hundreds of millions of years.

 
     
 
 
     



     
 
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