Similarities and differences: understanding homology and analogy
by the Understanding Evolution team
In everyday life, people look like one another for different reasons.
Two sisters, for example, might look alike because they both inherited
brown eyes and black hair from their father. On the other hand, two
people attending an Elvis impersonators’ convention may look alike
because they are both wearing rhinestone studded suits and long sideburns.
The similarity between the sisters is inherited, but the similarity
between the Elvis impersonators is not.
It works the same way in biology. Some traits shared by two living
things were inherited from their ancestor, and some similarities evolved in other ways. These are called homologies and analogies.
In this module, you’ll learn more about homologies and analogies
and why they are important. We’ll start by playing a game to get you
thinking about similarities and differences.