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Update on Genesis
| Article
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10763 |
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Section : |
NATURAL SCIENCE
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| Issue
Date : |
1 / 1986 |
3,037 Words |
| Author
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Andrew Scott
Dr. Andrew Scott is a free-lance science writer based in
Edinburgh, Scotland |
Take some matter, heat while stirring and wait…that is the modern version of genesis. The "fundamental forces" of gravity, electromagnetism, and the strong and weak nuclear forces are presumed to have done the rest. They made the elements form and then react to produce the chemical building blocks of life: nucleic acids made of sugars and bases, proteins made of amino acids, lipids and carbohydrates. Specific nucleic acids then began to direct the production of specific proteins. Nucleic acids and proteins that acted together to enhance their own multiplication thrived and continued to adapt. They became surrounded by membranes and evolved into complex cells and eventually into us.
But how much of this neat tale is firmly established, and how much remains hopeful speculation? In truth, the mechanism of almost every major step, from chemical precursors up to the first recognizable cells, is the subject of either controversy or complete bewilderment.
We do know that the universe is awash with the very chemicals most needed to make life. The elements carbon, hydrogen, nitrogen and oxygen make up 98 per cent of living matter and (except for helium) are the four most abundant elements in he universe. Since 1969, radio astronomy has shown the atmosphere of stars and the vastness of interstellar space to contain many of the ideal precursors needed to prime the chemistry of life. The discovery in space of molecules such as hydrogen cyanide, ammonia, formaldehyde and water, came after they had been shown to form amino acids, bases, sugars and so on in simulations of the conditions likely to have prevailed on early Earth.
These simulations of prebiotic chemistry began with the efforts of Stanley Miller in Chicago. In the early 1950s, Miller found that many of the amino acids used by modern life are formed in unexpected abundance when mixtures of gases such as methane, ammonia and water vapor, probably present in the primordial atmosphere, are exposed to "lighting storms" in the form of electric sparks.
Further simulations by Miller himself and many other researchers, such as Carl Sagan at Cornell and Juan Oro in Houston, have yielded most of the other building blocks of life. Although some problems remain (nucleotides, for example, have proved difficult to produce, and the conditions required to make different important products sometimes appear incompatible), even critics of the established theories accept that life's simple building blocks were probably available on the early Earth. This view is strengthened by the discovery of
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