Originally Posted by zain
All life is...
just this life form found is the most distant in terms of having a common ancestor..
at least that's what I found from this story!
Well, the single origin theory still holds i.e. all life forms on this planet are descended from a single common ancestor, who appeared shortly after the earth cooled down sufficiently to permit life to evolve, about 4 billion years ago. Life did not appear separately in different places and at different times.
All existing life whose DNA has been studied has the same genetic code. Since there's no particular reason why AAG should mean one amino acid rather than another, Lysine rather than Alanine, - it's completely arbitrary - that provides strong evidence that all living things surviving on earth descended from an ancestor for whom AAG meant Lysine.