The distribution of related animals and plants across the world shows that those organisms have common ancestor.
There is a term in biology- the most recent common ancestor (MRCA) and it is the most recent individual from which all the organisms are directly descended. It is hard for scientist to identify the exact MRCA, but it is estimated the time at which the MRCA lived (3.5 to 3.8 billion years ago). It is called Last Universal Common Ancestor (LUCA).
