Analogies do not necessarily result from common evolutionary descent. T he next step in classification is to determine whether or not the analogies are due to an independent evolutionary development or to descent from a common ancestor. If the latter is the case, then the two species are probably closely related and should be classified into the same or near biological categories. I f analogous structures are due to this sort of actual close genetic relationship, they are called homologies . Homologous structures are similar because they are inherited from a common ancestor that also had them.
T here can also be nonhomologous structural similarities between species.
In these cases, the common ancestor did not have the same anatomical structure. Instead, the similarities are due to independent acquisition in separate evolutionary lines. Such misleading similarities are called homoplasies . That is, they can be similar evolutionary developments after divergence from a common ancestor. For instance, some South American and African monkeys evolved relatively large body sizes independently of each other.