Answer
Comparative anatomy is valuable because the study of the structures of animals of several different species facilitates the understanding of the reasons for the development of human structures. It helps to explain the "repeating" of evolution by human embryological development and demonstrates convergent and divergent evolution. Not all features that look alike have the same origin; also,l features that perform similar functions may not have a common ancestry.
Work Step by Step
Many species have been used in comparative anatomy courses. Currently, cows and horses are not used in human anatomy courses, and dogs and primates, seldomly. The species commonly used are bird species, dogfish, rabbits, cats, rats, mice, hamsters, frogs, and lizards.
Study of nonhuman species helps to illustrate homologous features, analogous features, and vestigial features.
Homologous features: These are features that show origin from a common ancestor. Some structures that are homologous to the human forelimb are the forelimbs of cats, frogs, and lizards . Though they have a common ancestry/origin, they serve different functions in these living species. They demonstrate divergent evolution.
Analogous features: These features serve the same function in different living species, but they have different origins. They demonstrate convergent evolution. Examples are the wings of birds, bats and insects
The evolutionary ancestry of vestigial features like human coccyx, and appendix can be most convincingly established by doing dissections of herbivores and primates . Animals with tails have use for a tailbone or coccyx but humans have no use for a coccyx because they have lost their tails. Therefore, in humans a coccyx is a useless or vestigial feature-- an evolutionary residue. So too is the appendix which has a digestive function in rabbits and some other species, but serves no useful purpose in humans.
