There are many theories about how life arose.  One popular scientific theory states that Earth had existed for at least 1 billion years before the first signs of life appeared.  As the planet cooled, its atmosphere formed.  Rains filled the seas, where life began, perhaps because lightening sparked chemical reactions in the primeval “soup” of elements on the young planet.  Minerals from rocks formed and reformed new chemical combinations innumerable times, until an unusual chemical combination appeared: a living cell that could feed and reproduce itself.  Over millions of years, these cells evolved into plants and animals.  This is not the only theory of how life began on Earth.  Many other people believe that God created the Earth and all living things.