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...
