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The Origin Of Life

Page history last edited by Reedcope 13 years, 11 months ago

(Previous Page) Part 3: Mars            

    

 The Origin of Life

 

     The study of the possibility of life on Mars and the recent increases in empirical science has pointed a number of questions at the origin of life. As astronomers continued to question the existence of extraterrestrial life, they began to realize that solving the riddle of the origin of terrestrial life might possibly give us major insight into understanding how life formed or may form on another planet. If they can understand how life appeared on Earth in great detail, then they can pinpoint where and why extraterrestrial life might come into being. But just on Earth, however, the question of origin of life is one of the oldest and most puzzling questions in human history. Over the centuries, our knowledge of chemical and biological laws that govern life on Earth has vastly increased, but this knowledge has not really brought us any closer to understanding how they came to be in the first place. Still, scientists continue to formulate possible scenarios for the emergence of life on Earth. The implications of the debate are huge for the search for life on other planets. Nevertheless, knowing how life formed on Earth would not necessarily explain the likelihood or type of life on other planets, as it is difficult to separate the anomalies from the standards in a process with the sample size of one.

 

     Scientists often use three different theories to think about the origin of life: chance, design, and necessity theories. The chance theory is also known as the "happy accident" theory in which life was created out of mere chance or a series of random events that came together. According to Iris Fry, all that was needed for this highly improbable, fortuitous "first event" was one successful collision of molecules. This reduces the purpose of human life to, as the name of the theory suggests, a mere accident. It's also antipluralistic due to the significantly small probability of any sort of life emerging.  Therefore, even if life on Earth did originate in that manner, the odds of it happening again elsewhere in the universe are astronomically low.

 

     In contrast, believing in creation of life by a deity gives hope to those who seek a purpose. The design theory is the thought that the universe and everything in it was created by a deity or some intelligent creator.  This eliminates the chance problem because it is based on whatever the creator deems necessary to be done. Because design by an intelligent creator is unfalsifiable and cannot be proven by science, as David Hume wrote about in 1779, it is reliant on faith alone and generally dismissed by those who seek a solution based on evidence.

 

     The scafolding theory, presented in the Cairns-Smith theory, holds that life emerged out of a seriers of originally inorganic layer, much like the production of crystals.  In it, nonorganic structures similar to the RNA/DNA/protein loop existed prior to the organic structures and made it possible for them to develop.  The inorganic structures, thought to be made of clay, formed an arch around the organic structures and disappear when the organic structures are finished developing, after which they can undergo processes such as replication and other metabolic functions [1]. This theory is less controversial and scientists generally like it better than the other two because it follows the natural laws of chemistry, biology, and physics while also not excluding the designer because of the complexity of the system.  Each of these theories are possible but nevertheless have not been proven (for more information on this topic, see Is Life by Design, Chance, or Miracle).

 

     There are two main types of arguments regarding the origin of life and they come from how the question is viewed: deterministic and opportunistic. The deterministic viewpoint, as it taken by Richard Dawkins, believes that the outcome of evolution is determined by the conditions at the beginning.  Dawkins believed that once life is started it will follow a set path leading to the eventual evolution of intelligent beings. This idea would be possible through convergent evolution which means that similar organs emerge on different evolutionary pathways at the same time, an example is flight.  If the opportunistic viewpoint is taken, as it is by George Simpson, it is believed that the outcome of evolution varies depending upon small changes in conditions over a long period of time.  In this viewpoint intelligence is much less likely because evolution is contigent upon specific events occuring at a specific time, so once again we have come no closer to the answer of whether or not extraterrestrial life exists.

 

     Evolution and natural selection were also new ideas of the origin of life on Earth. These concepts are commonly used to back up arguments for plurality. Many believe that if life could evolve naturally on Earth then it could happen on other planets as well. Most of the time, this evolution included the emergence of intelligent life as well. Alfred Russell Wallace was one of the only scientists to use natural selection as part of his argument against evolution of intelligence and life in general. Wallace realized that human intelligence seemed to be beyond natural selection. He could find no reason in nature that would explain why man had developed intellect and morality. He therefore concluded that at some point, man stopped being affected by natural selection. He then drew the conclusion that God must have given man intellect and morality to enable man to maintain dominion over the earth.  Wallace also believed that evolution made it impossible for intelligent or humanoid life to occur again.  He took this opportunistic viewpoint after looking at the many branches on the "evolutionary tree" and concluding that there were too many different variables that led to that branching.  He thought that even if the conditions on a planet were exactly the same as those on early Earth that would be no assurance that intelligent or humanoid life would emerge.  Wallace based his anti-pluralistic views on the currently, widely accepted knowledge of astronomy. 

 

     Wallace lays out the factors he believed to be necessary for the emergence of life on earth. The first of these factors is the sun. Like Whewell, he believed the Earth receives the perfect amount of heat to sustain life without scorching the surface of the planet. The second factor is the atmosphere. The Earth's atmosphere is the sufficient density to allow the production of water vapor. This vapor is needed to equalize heat and cold on Earth allowing us a temperate environment. The amount of atmosphere is based largely on the size of the planet. "This one feature alone probably renders Mars quite unsuitable." The oceans on Earth are also an impotant factor needed for the development of life. The currents keep a continuous circulation of vapors and water and therefore aid in the regulation of temperature. The moon which causes these currents is therefore needed, rendering Venus unsuitable for intelligent life as well. The final factor for life-sustainment is "the uninterrupted supply of atmospheric dust, which is now known to be necessary for the production of rain clouds." Without rain and mist, life as we know it on Earth cannot possibly exist elsewhere.  Furthermore, tectonic plate activity is considered important to the existence of life. Without moving landmasses, the atmosphere would not be recycled as it is. Certain elements would be too bound in the earth and others would be too prevalent in the air for life to possibly exist. All these important pieces of the existence of life add up to create a somewhat unique and as far as we can tell ideal ground for the origination and sustenance of life.

 

     What these theories ultimately comes down to is religion vs. science.  Religion creates purpose and has the belief in a deity who has created the universe for a reason.  It is also something that puts faith in unseen things and deals with the supernatural. With the supernatural, it has to be revealed through a revelatory experience to be seen. Science is something that is defined by empirical evidence and observation, which is testable and repeatable. It relies on natural law to explain things, unlike religion, which is based truly on faith. The study of this issue through science is also problematic because the assumptions of science may not apply as scientists have tried them. The idea of a supernatural beginning holds on strongly because science is still unable to completely explain the origin of life, though there are theories and facts that can point us at what we can think is likely to have happened.

                                                                  

 (Next Page) Part 5: SETI, Fermi and the Anthropic Principle


[1] Fry, Iris. The Emergence of Life on Earth. p. 185.

Comments (2)

Peter Ramberg said

at 10:35 am on Dec 6, 2008

I would move the penultimate paragraph to near the beginning of this section (combine it with the first?). It generates a framework of the three possibilities that you can then "unpack" with more specific examples. Wallace as an example of design, the "scaffolding" theory of life's orgins, and the "happy accident" theory of Crick/Monod (as summarized in Fry) Each can use a paragraph, followed by a last paragraph on the implications for etl. This should take five paragraphs, perhaps 6-7 if you expand it more.

Also, add links to the previous and next sections of the essay.

Reedcope said

at 5:50 pm on Dec 6, 2008

This page needs quite a bit of elaboration, and it is missing citations for the quotes. If someone else can find where these quotations came from, I'll work on elaborating on some of the paragraphs I think are lacking.

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