Formation of Earth Earth was formed about 4000 to 5000 millions of years ago. Fossils from microscopic animals and bacterias prove that life surged about 3.000 millions of years ago. It is likely, that initially the Earth's atmosphere contained methane, ammoniac, carbon dioxide and other gases that are abundant in other planets from the Solar System. It seems likely that Earth surged from the combination of different chemicals., The sea was probable made of organic compounds.

The most important step was the appearance of molecules that autorreplicated themselves and were capable of producing copies of them. Once these self-replicating molecules were formed, something similar to the Darwinian natural selection might have occured.Organisms with good replication might have prevailed however the ones with bad replication died. A molecular form of natural selection led to a higher efficiency between replicated molecules.

The molecules which survived developed hability to autoconserve themselves and to reproduce. This was probably due to the multiplication of molecules (proteins). These kind of bacteria gave place to the first fossils. The following evolution might be due to the continuation on natural selection.