living things in the same class are more closely related than living things in different classes
population is not group_of_similar_living_things. living_together is not cohabitation_situation. similarity is not sameness. similarity is sameness. life is another_way_of_saying_living_things. population is group_of_similar_living_things. living_together is cohabitation_situation. one_of_things is not classes. homology is not similarity. homology is similarity.