Origin of life

Earth formed about 4.6 billion years ago (= 4.6 Giga years) as third planet in a series of nine circling around a star, the Sun. The Sun and the planets are made from stellardebris of stars that came to the end of their existance. Everything we see around us is actually recycled stardust.After the formation Earth was a pockmarked planet of roughly uniform composition and had an early atmosphere of mainly hydrogen (H2). Then radioactive heating began to melt the interior and the core was formed. Now this heating had as a consequense that degassing from the planets interior created a second atmospere rich in water (H2O), carbon dioxide (CO2), methane (CH4) and Ammonia (NH3). When the surface had cooled enough intense rains began to fall and created the oceans.
It is generaly believed in science that this "prebiotic soup" as it is called is where life originated. The famous Miller-Urey experiment duplicated the conditions of early Earth in a laboratory (Orgel, 1994). In a self-contained apparatus an "atmosphere" consisting of hydrogen, water, methane and ammonia was created above an "ocean" of water. These gasses were subjected to "lightning" in the formof an electrical discharge. They found that 10% of the carbon (C) in the system had converted into organic compounds and 2% of this carbon went on to make amino-acids, the buildingblocks of our carbon-based life.Although doubt has arisen because recent investigations indicate that Earth's early atmosphere may have contained more gasses than in the experiment, like CO2 (Orgel, 1994)(De Jager, 1995). But it is still the best theory we have.These amino-acids that formed on Earth are very important, they are the buildingblocks of the nucleic-acids RNA and DNA which in their turn carry the genetic information of organisms. Whether RNA arose spontanous or replaced some earlier geneticsystem is not quite clear. But its development was probably the key in the development of life. It very likely led to the synthesis of proteins, the formation of DNA and the emergence of a cell that could be the ancestor of all

current lifeforms as theory implies. (Orgel, 1994).
Nowadays one of the vital needs for survival of complex organisms is the presence of oxigen (O2). Yet if one looks at Miller-Urey's experiment one sees that no free oxigen has been included in the initial mixture of gasses. Free oxigen was little or not present at the creation of life on the Earth. For it is an agressive element, it oxidizes other chemicals; it subtracts hydrogen from existing molecules. Therefore under oxidizing conditions amino-acids do not or very little form.The atmosphere plays a major part in the creation of life and sustaining it