Without an understanding of how life originated it would seem only as one reasonable conclusion that all life originated from one common ancestor. Perhaps, when new life forms it will forms in similar ways. So, on one side of the earth a new life arose from the primordial ooze while on the other side of the earth the same process created a different life form. But, when one would examine the two they might conclude them as related because the separate forms of life share DNA (or just RNA) in their make up producing proteins in similar ways. The originating spark of life might produce similar life forms.
Evolution
Without an understanding of how life originated it would seem only as one reasonable conclusion that all life originated from one common ancestor. Perhaps, when new life forms it will forms in similar ways. So, on one side of the earth a new life arose from the primordial ooze while on the other side of the earth the same process created a different life form. But, when one would examine the two they might conclude them as related because the separate forms of life share DNA (or just RNA) in their make up producing proteins in similar ways. The originating spark of life might produce similar life forms.