What are homologous structures and what do they indicate about the evolutionary relationship?

Homologous structures are animals' and organisms' organs or skeletal elements. Homology was explained by Charles Darwin's theory of evolution.

Explanation:

Homology is showing the relationship between organs or skeletal elements of different organisms. Those characters, actually Homologous structures, are inherited from their common ancestor.

Why is this important for the evolutionary relationship which Charles Darwin's theory is showing?  It's important because nowadays all those differences were happened during the evolutionary divergence of organisms.

Nothing is unique in nature so homology is everywhere.

Homologous structures are organs of animals which are same in terms of basic structure but differ entirely in function.  

Explanation:

Homologous organs indicate common ancestry among organisms and the functions differed as apart of adaptations according to the environment. Since the same structure has developed along different directions homologous structures indicate divergent evolution.

There are several examples of homologous organs.

Forelimbs of mammals like human bat cheetah whale etc are homologous structures. They have the same structure but entirely different functions. Whales use forelimbs for swimming, bats use forelimbs for flight and cheetah uses forelimbs to run.  

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