There is no oxygen present. Volcanoes pump massive quantities of gases, dust and ash into the atmosphere. Giant electrical thunderstorms are commonplace. Life as we know it could not have evolved under these conditions. The oceans provide a more protected environment.
Liquid water acts as a UV shield, protecting potential organisms from UV irradiation.
The stage is set for life to appear in the oceans. Components of Life. Most of us think of the living world as a complex and diverse place. The differences between a redwood tree and a mite, or between a bacterium and a baboon, are so great that it is hard to believe that all life is made up of only a few essential types of chemical compounds, assembled in a myriad of different manners. Principal chemical constituents of life.