The Origin Of Life Essays - Origin Of Life, Astrobiology

The Origin Of Life The origin of Life There are many theories where life came from, but none of them is proven to be the right one. The obvious theory that life originated on earth is not accepted by everyone. One reason of disbelief in this theory that life originated on earth is a lack of time. It was an early belief that life originated through a slow and long process (many scientists do not share this belief though), probably too short and too long for the time life had on our planet. Life must have been formed within a period of approximately 200 million years. If we represent the whole Christian era - two thousand years - by one inch, the time available for the emergence of life could measure as much as 1.5 miles. Another theory called panspermia claims that life was created somewhere else, not on earth, and traveled to our planet via meteorites or comets. Another version of panspermia claimed by Francis Crick and Leslie Orgel is that life was brought to earth by a spaceship sent by a more intellectual species. Thi s theory is called directed panspermia. The last theory might be the least likely one, since there is no actual evidence for spaceships or species from other planets. The panspermia theory can not be disproved and it might be possible that life came to earth via a comet. Bodies like comets contain organic molecules which are similar to the molecules of living organisms, but most scientists say that reactions creating these molecules take place out there. We can not find an answer for this question since neither theory can totally be proven. Supporters of the panspermia theory say that there was not enough time for life to originate. Supporters of the theory that life originated on earth can not prove that life did not come from outer space. The Christian theory that life was created by God is abstract and will not be discussed further in this paper. Personally I believe in the theory that life was born on earth. Six elements are needed to create life. Almost every organic matter can be summarized symbolically in these six different elements: carbon (C), hydrogen (H), nitrogen (N), oxygen (O), phosphorus (P), and sulfur (S). One also says that life can be explained by the formula CHNOPS. These are the main characters in the creation of life chemically. Knowing that these six elements are needed to create life we have to find out in what condition these elements were. It is still not known what the composition of the primitive atmosphere was. It was believed that the atmosphere consisted of hydrogen (H2), methane (CH4), ammonia (NH3), and water vapor (H2O). But this is doubted today. Scientists say that carbon probably was not present in the combination with hydrogen (methane). It probably was present in the combination with oxygen, mostly with carbon dioxide, or CO2. In the early years of the earth, about 4 billion years ago, there was no oxygen in the atmosphere of the world. There needs to be life in order to have free oxygen. What was the temperature on earth in these days? It is practically impossible to find the answer to this question, but it is an important issue to know since temperature limits the life span of biomolecules, such as proteins, nucleic acids, and the blocks they were contained in. Thinking of this fact chemists assume that the temperature of the environment might have been very cold, possibly under the freezing point. Geochemists, though, do not think this way. They believe that temperature might have been close to the boiling point of water, but they also believe that there must have been a high atmospheric pressure, which kept the oceans from boiling. What was the sun like? Four billion years ago the sun was cooler than today. It sent out probably 25% less energy to the Earth than today. But this was probably offset by the greenhouse effect of atmospheric carbon dioxide. There definitely was a lot of water in the beginning of life. Water is the vital element of any living organism. The atmosphere above the water was heavy with carbon dioxide, nitrogen, hydrogen