What are homologous structures? Give an example. Is it necessary that homologous structures always have a common ancestor? Justify your answer.
Homologous structures are the structures that have the same structural plan and origin but have different functions.
Example: Wings of birds and forelimbs of humans perform different functions but they have similar skeletal structure because they have the same origin.
Yes, it is necessary that homologous structures always have a common ancestor.
As the above example suggests, the basic structure of both are the same but they were modified to perform different functions . Hence, this shows that they have both evolved from a common ancestor.