Comparative Anatomy as Evidence for Evolution
What is comparative anatomy?
Break it down: "comparative" = comparing different objects "anatomy" = the structure of an organism
Put it together: Comparative anatomy = Comparing different structures of an organism
What is a homologous structure?
Break it down: "homo" = "same" "logos" = "equal to"
Put it together: Homologous structure = a structure that looks the same between organisms
Scientists use comparative anatomy of homologous structures to provide evidence for evolution.
For example, the arm of a human, the front leg of a cat, the front flipper of a whale, and the wing of a bat do not look alike and are not used in the same way. But under the surface, they ARE similar.
Look at the figure below. The bones of a human arm are similar in structure and order to the bones in the front limbs of a cat, a dolphin, and a bat. These similarities suggest that cats, whales, bats, and humans had a common ancestor. Over millions of years, changes occurred in the limb bones as the animals adapted to their different environments. Eventually, the bones performed different functions in each type of animal.