evolutionary history of life

The evolutionary history of life and the origin of life are fields of ongoing geological and biological research. Although it is not necessary to understand the origin of life on earth to accept evolution by natural selection, the origin of life and its evolutionary history can help shed light on evolutionary processes. The current scientific consensus is that the complex biochemistry that makes up life came from simpler chemical reactions, but it is unclear how this occurred. Not much is certain about the earliest developments in life, the structure of the first living things, or the identity and nature of any last universal common ancestor or ancestral gene pool. Consequently, there is no scientific consensus on how life began, but proposals include self-replicating molecules such as RNA, and the assembly of simple cells.
See more at Wikipedia.org...