Metabolism and genetics either could be the origin the life on Earth, but the exact reason or process is not known. Therefore, it can be said that the main hypothesis supporting the fact that genetics came first is RNA world hypothesis and the one which says that it could be metabolism is protein world hypothesis and each of it has been discussed below.
Now the question still remains as to how the earliest form of life was found or formed on Earth. It is believed that some or the other kind of chemical change or reaction would have taken place that gave rise to the life form and that has after years and years of development, the life form is what it is now. Another one is how the origin of the cell membrane came into force, as it has a very important function in day to day life, keeping in mind the multi-cellular and the unicellular animals that occupy the earth.
Creationism though is not a scientific approach, still tries to give answer as to how the life on earth originated. It suggests that there was an “old earth” and a “new earth” is something that came in just few thousand years ago and it has been suggested by the fossil records thus found. These are the evidences found to support the oldest from of life on earth (Orgel, 1994).
If one looks at the fossil records which have been formed, the earliest full life forms that were noticed were the microfossils or the microorganisms, which were found in silica rock and assumed to be hydrothermal vents, which were found somewhere in Canada and are approximately 4.28 billion years old. If one was to believe that this is the oldest record found, then one gains the capacity to say that life just emerged on earth post formation of the oceans, which took place about 4.4 billion years ago.
Back in 2002, it was found that stromatolites contained fossilized cyanobacteria which were assumed to be approximately 3.45 billion years old. It was unanimously agreed that stromatolites, are the only and the oldest form of life on earth according to the records which are available. The timing of this should lie somewhere in between 4.4 billion years ago (when liquefaction of water also took place) and 3.55 billion years ago.