Question

What are homologous organs?

Answer 1

Comparative anatomy is a field of science that studies the differences and similarities between the anatomy of two species.

Complete answer:
Evolution can be described as genetic changes which occur in a population over a period of time. Under evolution, one of the parameters is comparative anatomy.
Comparative anatomy is basically the study of the anatomy of two species and finding the similarities and differences between them. The two major concepts that are studied under anatomy are,
Homologous structures
An organ is known as a homologous organ if they have the same ancestor but the function differs.
Example: The arm of whales, humans and birds has been derived from the same ancestor but they perform different function

Analogous structures
An organ is known as an analogous organ if they have the same structure but the ancestor differs.
These organs have very similar structure and they perform nearly the same function.
Example: Wings of bird and insects have the same function i.e. to fly and they have different structure

Additional information: There are various evidences that support evolution

1. Comparative anatomy - Presence of analogous and homologous organs
   2)Development of embryo - The embryos of various organisms have a similarly until a certain period of gestation
   3)Fossils of plants and animals - It is the remains of non-degraded parts of the living plants and animals

Note: It is very important that one does not get confused between homologous and analogous structures.
1)Homologous - Same ancestor, different function
2)Analogous - Different ancestor, same function