Final answer:
Vestigial structures are body parts that have lost their function through evolution. They provide evidence for evolution by showing that organisms have changed their use of structures or that structures are no longer needed. Examples include the wings of flightless birds and the appendix in humans.
Step-by-step explanation:
Vestigial structures are body parts that have lost their function through evolution. These structures provide evidence for evolution because they suggest that an organism has changed from using the structure to not using it, or using it for a different purpose. For example, the wings of an ostrich have lost their original function for flight, but they are still present as vestigial structures. Other examples include the human appendix and the hind leg bones in whales.
Vestigial structures support the concept of common ancestry, which is a key component of evolution. When different organisms have similar vestigial structures, it suggests that they share a common ancestor. For instance, the presence of vestigial pelvic bones in snakes, even though they have no legs, indicates that snakes descended from reptiles that did have legs.
Overall, the presence of vestigial structures reinforces the idea that organisms have evolved over time and helps to paint a picture of the interconnections between different species.