A Human (My Brother)
Homologous structures are body parts that are alike because the species in question share a common ancestor. These structures may serve the same or different functions. For example, the wing of a bird and the arm of a human serve very different functions, but are considered homologous structures because of the evolutionary relationship between birds and humans. In the picture above, my brothers arms can be considered a homologous structure, because humans have evolved their arm from long before to now.