1.1) Primitive Conditions on the EarthConditions on the early Earth, dating back 4 billion years, are very different today. Considering the “Big Bang Theory,” the conditions were very extreme in terms of temperature. As a result, the earth was extremely hot, causing the liquid to evaporate into the atmosphere. As the earth cooled, water vapors in the atmosphere condensed and fell as rain. They did not evaporate but remained in pools which eventually transformed into lakes and oceans. On top of that, the earth was constantly bombarded with meteorites and other space debris due to the lack of protection. It is therefore believed that the early Earth's atmosphere was composed of hydrogen, nitrogen, ammonia, methane, water vapor and carbon dioxide. It should be noted here that the early Earth's atmosphere lacked oxygen. The early atmosphere was composed of hot hydrogen gas, not light enough to be held by Earth's gravity. Later, water vapor, carbon monoxide, carbon dioxide, nitrogen and methane replaced the hydrogen in the atmosphere. The seas and oceans were formed by the condensation of these vapors. Other conditions such as lightning, volcanic activity and ultraviolet radiation have also occurred. It is in this scenario that life began.1.2) Conditions that support life on Earth1.2.1.1) OxygenIt is a highly reactive gas that can form compounds with many other elements. It is the third most abundant element on Earth, after hydrogen and helium. It is the most abundant element in mass in the earth's crust. About 20.8% oxygen is present in Earth's air. Proteins, carbohydrates, fats, bones, teeth all require oxygen and therefore life is not possible without oxygen. Above all, all this...... middle of paper ...... less than it is today. Recently, Jeffrey Bada of the Scripps Institution of Oceanography proposed that the oceans would not completely freeze if, at that time, the Sun and Earth had been the same temperature. Instead, he calculates that only the top 300 meters of the ocean would freeze. The ice layer constitutes a protective shield by preventing ultraviolet rays, responsible for the destruction of organic compounds, from accessing the developing molecules. The water beneath the ice is cold, allowing organic molecules to survive for much longer periods. These organic molecules must have migrated from the thermal vents. The components necessary for organic synthesis such as Strecker synthesis would have been provided and kept stable, while the ocean floor would have provided a place for organic materials to gather and react..