Homologous structures are anatomical traits that multiple different species share due to a common ancestor. For example, the canine and human both have a humerus, radius ulna, and carpals in each forelimb. Although they look quite different on the exterior and vary in function, they are similar in skeletal structure. More importantly, they come from the same structures in the embryo. This comparison of homologous structures can suggest that canines and humans evolved from a common ancestor.