What is the definition of life and how did it get here? This question sums up what was discussed today in class.  There are many qualities that we agreed helped to define life:  capability of Darwinian evolution, a carbon base, the use of energy to do work, internal metabolism, reproduction, and the appearance of design. What actually constitutes life is difficult to define, but it is agreed that life is a complex and complicated machine of biomolecules working together with the appearance of design. The next part of the question is how did life form on earth?  To this end, scientists look for a naturalistic solution.  What is a naturalistic solution?  A naturalistic solution can be tested and falsified.  It is reliant on laws of nature, i.e. laws of physics, chemistry and biology, unlike a "super-naturalistic" solution to the origin of life where events can't be tested because it defies the natural laws of the universe. Oparin and Haldane looked for a naturalistic way in which life may have been formed on earth.  Both men had different ideas that centered around an organic "soup" found on young earth.

 

The Space Age

    

      The Space Age helped to firmly integrate biology and astronomy, which before had been considered very diferent fields of science. The space race gave biologists the chance to look for other life in our solar system.  Biologists saw opportunities to get NASA funding for investigation into extraterrestrial life as planetary contamination and life detection became pressing issues. Theories and experiments on the origins of life were seen in an increasingly extraterrestrial context, and the search for a universal biology began.  Also, the discovery of organic material on meteorites and comets also pushed biology into the stars (Dick, pp171-72).

 

Panspermia 

   

 A more recent theory on the origin of life is panspermia, introduced in the 20th century, in which scientists postulate that life may have come to earth from elsewhere in the universe. There are three forms panspermia generally takes: 

     (1)  life forms such as bacteria or other simple organisms arrived on Earth via a meteorite.

     (2)  alien life might have "seeded" Earth with life. This theory is not regarded very well in the scientific community in general.

     (3) a chunk of Mars containing Martian amino acids and proteins landed on Earth. From this, DNA could be created.

 

      According to Steven Dick, observational evidence of organic synthesis and prebiotic chemicals in meteorites, comets, dust, ice, the atmospheres of the Jovian planets or their satellites, and interstellar molecular clouds gave rise to the belief that these organic life forms had been delivered by impacts from outer space. Panspermia as a scientific explanation for the origin of life is very short sighted: it simply tries to explain the origin of life on Earth, not necessarily the exact origin of life at all.  Thus, biologists, physicists, and chemists generally dismissed it.

 

 

     What it did do, though, was have an impact on the extraterrestrial life debate.  Since exobiologists who studied these meteorites were sure that these organic life forms came from space, they lost no opportunity to point out that the ease with which organics were apparently formed boded well for extraterrestrial life.   

 

     "There is every reason now to see in the origin of life not a "happy accident" but a completely regular phenomenon, an inherent component ot the total evolutionary development of our planet.  The search for life beyond Earth is thus only a part of the more general question which confronts science, of the origin of life in the universe." 

               -- A.I. Oparin (1975)

 

     

This idea links up with both the search for a naturalistic formation of life but also with the presentation and the joining of biology and astronomy.  A.I. Oparin and J.B.S. Haldane both proposed that the problem of the origin of life should be explained entirely in terms of the general laws of physics and chemistry as applied to primitive Earth conditions (Dick, 171). Oparin agrees that there must be something within earth that caused the generation of life, not a chance meteor hitting the surface but "an inherent component of the total evolutionary development of our planet." Both Oparin and Haldene agree that the early Earth had a certain set of conditions that created an organic soup and in this soup life had formed. They both had two different theories as to how life formed out of this soup of molecules.  And now the search for life outside of earth is asked the same question.  Perhaps there is a universal biology, so way in which the origins of everything can be linked.

     In 1953 a direct test of the Oparin-Haldane hypothesis was performed by Stanley Miller and Urey, his graduate advisor.  Urey and Miller created an experimental setup which included a chamber with gases thought to be in abundance in Earth's early atmosphere, and electrodes which created sparks through this gas.  These sparks simulated lightning, which was thought to provide the first jolt of energy to create the first building blocks of life.  During this experiment, they found that many amino acids were present in their "primordial soup" and in the correct proportions as found on Earth.  This finding was not as revolutionary as it might have been as a little while later it was shown that the primative atmosphere was not a reducing atmosphere as was previously thought and as was used in the Miller-Urey experiment. 

     Sidney Fox was interested in where proteins come from and he made soups of amino acids and wanted to see what proteins would form sopontaneously.  He found that the amino acids that show up in certain proteins follows the laws of chemistry and that protein formation is not random.  He also found that mircospheres formed after a certain number of proteins were formed and they were like Oparins' coacervates.